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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.14200">arXiv:2407.14200</a> <span> [<a href="https://arxiv.org/pdf/2407.14200">pdf</a>, <a href="https://arxiv.org/format/2407.14200">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevAccelBeams.27.111001">10.1103/PhysRevAccelBeams.27.111001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-density gas target at the LHCb experiment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Garcia%2C+O+B">O. Boente Garcia</a>, <a href="/search/physics?searchtype=author&query=Bregliozzi%2C+G">G. Bregliozzi</a>, <a href="/search/physics?searchtype=author&query=Calegari%2C+D">D. Calegari</a>, <a href="/search/physics?searchtype=author&query=Carassiti%2C+V">V. Carassiti</a>, <a href="/search/physics?searchtype=author&query=Ciullo%2C+G">G. Ciullo</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Pinto%2C+P+C">P. Costa Pinto</a>, <a href="/search/physics?searchtype=author&query=De+Angelis%2C+C">C. De Angelis</a>, <a href="/search/physics?searchtype=author&query=Di+Nezza%2C+P">P. Di Nezza</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a>, <a href="/search/physics?searchtype=author&query=Ferro-Luzzi%2C+M">M. Ferro-Luzzi</a>, <a href="/search/physics?searchtype=author&query=Fleuret%2C+F">F. Fleuret</a>, <a href="/search/physics?searchtype=author&query=Graziani%2C+G">G. Graziani</a>, <a href="/search/physics?searchtype=author&query=Kotriakhova%2C+S">S. Kotriakhova</a>, <a href="/search/physics?searchtype=author&query=Lenisa%2C+P">P. Lenisa</a>, <a href="/search/physics?searchtype=author&query=Lu%2C+Q">Q. Lu</a>, <a href="/search/physics?searchtype=author&query=Lucarelli%2C+C">C. Lucarelli</a>, <a href="/search/physics?searchtype=author&query=Maurice%2C+E">E. Maurice</a>, <a href="/search/physics?searchtype=author&query=Mariani%2C+S">S. Mariani</a>, <a href="/search/physics?searchtype=author&query=Mattioli%2C+K">K. Mattioli</a>, <a href="/search/physics?searchtype=author&query=Milovanovic%2C+M">M. Milovanovic</a>, <a href="/search/physics?searchtype=author&query=Pappalardo%2C+L+L">L. L. Pappalardo</a>, <a href="/search/physics?searchtype=author&query=Parragh%2C+D+M">D. M. Parragh</a>, <a href="/search/physics?searchtype=author&query=Piccoli%2C+A">A. Piccoli</a> , et al. (10 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.14200v2-abstract-short" style="display: inline;"> The recently installed internal gas target at LHCb presents exceptional opportunities for an extensive physics program for heavy-ion, hadron, spin, and astroparticle physics. A storage cell placed in the LHC primary vacuum, an advanced Gas Feed System, the availability of multi-TeV proton and ion beams and the recent upgrade of the LHCb detector make this project unique worldwide. In this paper, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.14200v2-abstract-full').style.display = 'inline'; document.getElementById('2407.14200v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.14200v2-abstract-full" style="display: none;"> The recently installed internal gas target at LHCb presents exceptional opportunities for an extensive physics program for heavy-ion, hadron, spin, and astroparticle physics. A storage cell placed in the LHC primary vacuum, an advanced Gas Feed System, the availability of multi-TeV proton and ion beams and the recent upgrade of the LHCb detector make this project unique worldwide. In this paper, we outline the main components of the system, the physics prospects it offers and the hardware challenges encountered during its implementation. The commissioning phase has yielded promising results, demonstrating that fixed-target collisions can occur concurrently with the collider mode without compromising efficient data acquisition and high-quality reconstruction of beam-gas and beam-beam interactions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.14200v2-abstract-full').style.display = 'none'; document.getElementById('2407.14200v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Editors' Suggestion</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-DP-2024-002 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review ACCELERATORS AND BEAMS 27, 111001 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.13615">arXiv:2404.13615</a> <span> [<a href="https://arxiv.org/pdf/2404.13615">pdf</a>, <a href="https://arxiv.org/format/2404.13615">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> </div> <p class="title is-5 mathjax"> The LHCb VELO Upgrade Module Construction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Alexander%2C+M">M. Alexander</a>, <a href="/search/physics?searchtype=author&query=Bertella%2C+C">C. Bertella</a>, <a href="/search/physics?searchtype=author&query=Biolchini%2C+A">A. Biolchini</a>, <a href="/search/physics?searchtype=author&query=Bitadze%2C+A">A. Bitadze</a>, <a href="/search/physics?searchtype=author&query=Bogdanova%2C+G">G. Bogdanova</a>, <a href="/search/physics?searchtype=author&query=Borghi%2C+S">S. Borghi</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T+J+V">T. J. V. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Bridges%2C+K">K. Bridges</a>, <a href="/search/physics?searchtype=author&query=Brock%2C+M">M. Brock</a>, <a href="/search/physics?searchtype=author&query=Burke%2C+A+T">A. T. Burke</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">W. Byczynski</a>, <a href="/search/physics?searchtype=author&query=Carroll%2C+J">J. Carroll</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Davis%2C+A">A. Davis</a>, <a href="/search/physics?searchtype=author&query=Francisco%2C+O+D+A">O. De Aguiar Francisco</a>, <a href="/search/physics?searchtype=author&query=De+Bruyn%2C+K">K. De Bruyn</a>, <a href="/search/physics?searchtype=author&query=De+Capua%2C+S">S. De Capua</a>, <a href="/search/physics?searchtype=author&query=De+Roo%2C+K">K. De Roo</a>, <a href="/search/physics?searchtype=author&query=Doherty%2C+F">F. Doherty</a>, <a href="/search/physics?searchtype=author&query=Douglas%2C+L">L. Douglas</a>, <a href="/search/physics?searchtype=author&query=Dufour%2C+L">L. Dufour</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a> , et al. (62 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.13615v1-abstract-short" style="display: inline;"> The LHCb detector has undergone a major upgrade for LHC Run 3. This Upgrade I detector facilitates operation at higher luminosity and utilises full-detector information at the LHC collision rate, critically including the use of vertex information. A new vertex locator system, the VELO Upgrade, has been constructed. The core element of the new VELO are the double-sided pixelated hybrid silicon dete… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.13615v1-abstract-full').style.display = 'inline'; document.getElementById('2404.13615v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.13615v1-abstract-full" style="display: none;"> The LHCb detector has undergone a major upgrade for LHC Run 3. This Upgrade I detector facilitates operation at higher luminosity and utilises full-detector information at the LHC collision rate, critically including the use of vertex information. A new vertex locator system, the VELO Upgrade, has been constructed. The core element of the new VELO are the double-sided pixelated hybrid silicon detector modules which operate in vacuum close to the LHC beam in a high radiation environment. The construction and quality assurance tests of these modules are described in this paper. The modules incorporate 200 \mum thick, n-on-p silicon sensors bump-bonded to 130 \nm technology ASICs. These are attached with high precision to a silicon microchannel substrate that uses evaporative CO$_2$ cooling. The ASICs are controlled and read out with flexible printed circuits that are glued to the substrate and wire-bonded to the chips. The mechanical support of the module is given by a carbon fibre plate, two carbon fibre rods and an aluminium plate. The sensor attachment was achieved with an average precision of 21 $\mathrm{渭m}$, more than 99.5\% of all pixels are fully functional, and a thermal figure of merit of 3 \mathrm{Kcm^{2}W^{-1}}$ was achieved. The production of the modules was successfully completed in 2021, with the final assembly and installation completed in time for data taking in 2022. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.13615v1-abstract-full').style.display = 'none'; document.getElementById('2404.13615v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-DP-2024-001 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.14195">arXiv:2308.14195</a> <span> [<a href="https://arxiv.org/pdf/2308.14195">pdf</a>, <a href="https://arxiv.org/format/2308.14195">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2023.169046">10.1016/j.nima.2023.169046 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fabrication of a Silicon Electron Multiplier sensor using Metal Assisted Chemical Etching and its characterisation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Halvorsen%2C+M+M">Marius M忙hlum Halvorsen</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">Victor Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Sandaker%2C+H">Heidi Sandaker</a>, <a href="/search/physics?searchtype=author&query=Romano%2C+L">Lucia Romano</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.14195v1-abstract-short" style="display: inline;"> The Silicon Electron Multiplier (SiEM) sensor is a novel sensor concept that enables charge multiplication by high electric fields generated by embedded metal electrodes within the sensor bulk. Metal assisted chemical etching (MacEtch) in gas phase with platinum as a catalyst has been used to fabricate test structures consisting of vertically aligned silicon pillars and strips on top of a silicon… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.14195v1-abstract-full').style.display = 'inline'; document.getElementById('2308.14195v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.14195v1-abstract-full" style="display: none;"> The Silicon Electron Multiplier (SiEM) sensor is a novel sensor concept that enables charge multiplication by high electric fields generated by embedded metal electrodes within the sensor bulk. Metal assisted chemical etching (MacEtch) in gas phase with platinum as a catalyst has been used to fabricate test structures consisting of vertically aligned silicon pillars and strips on top of a silicon bulk. The pillars exceed 10 $渭m$ in height with a diameter of 1.0 $渭m$ and are arranged as a hexagonal lattice with a pitch of 1.5 $渭m$. Electrical characterisations through current $-$ voltage measurements inside a scanning electron microscope and a climate chamber have demonstrated that the MacEtch process is compatible with active media and p-n junctions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.14195v1-abstract-full').style.display = 'none'; document.getElementById('2308.14195v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 16 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.10515">arXiv:2305.10515</a> <span> [<a href="https://arxiv.org/pdf/2305.10515">pdf</a>, <a href="https://arxiv.org/format/2305.10515">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/19/05/P05065">10.1088/1748-0221/19/05/P05065 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The LHCb upgrade I </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=LHCb+collaboration"> LHCb collaboration</a>, <a href="/search/physics?searchtype=author&query=Aaij%2C+R">R. Aaij</a>, <a href="/search/physics?searchtype=author&query=Abdelmotteleb%2C+A+S+W">A. S. W. Abdelmotteleb</a>, <a href="/search/physics?searchtype=author&query=Beteta%2C+C+A">C. Abellan Beteta</a>, <a href="/search/physics?searchtype=author&query=Abudin%C3%A9n%2C+F">F. Abudin茅n</a>, <a href="/search/physics?searchtype=author&query=Achard%2C+C">C. Achard</a>, <a href="/search/physics?searchtype=author&query=Ackernley%2C+T">T. Ackernley</a>, <a href="/search/physics?searchtype=author&query=Adeva%2C+B">B. Adeva</a>, <a href="/search/physics?searchtype=author&query=Adinolfi%2C+M">M. Adinolfi</a>, <a href="/search/physics?searchtype=author&query=Adlarson%2C+P">P. Adlarson</a>, <a href="/search/physics?searchtype=author&query=Afsharnia%2C+H">H. Afsharnia</a>, <a href="/search/physics?searchtype=author&query=Agapopoulou%2C+C">C. Agapopoulou</a>, <a href="/search/physics?searchtype=author&query=Aidala%2C+C+A">C. A. Aidala</a>, <a href="/search/physics?searchtype=author&query=Ajaltouni%2C+Z">Z. Ajaltouni</a>, <a href="/search/physics?searchtype=author&query=Akar%2C+S">S. Akar</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Albicocco%2C+P">P. Albicocco</a>, <a href="/search/physics?searchtype=author&query=Albrecht%2C+J">J. Albrecht</a>, <a href="/search/physics?searchtype=author&query=Alessio%2C+F">F. Alessio</a>, <a href="/search/physics?searchtype=author&query=Alexander%2C+M">M. Alexander</a>, <a href="/search/physics?searchtype=author&query=Albero%2C+A+A">A. Alfonso Albero</a>, <a href="/search/physics?searchtype=author&query=Aliouche%2C+Z">Z. Aliouche</a>, <a href="/search/physics?searchtype=author&query=Cartelle%2C+P+A">P. Alvarez Cartelle</a>, <a href="/search/physics?searchtype=author&query=Amalric%2C+R">R. Amalric</a>, <a href="/search/physics?searchtype=author&query=Amato%2C+S">S. Amato</a> , et al. (1298 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.10515v2-abstract-short" style="display: inline;"> The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their select… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.10515v2-abstract-full').style.display = 'inline'; document.getElementById('2305.10515v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.10515v2-abstract-full" style="display: none;"> The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.10515v2-abstract-full').style.display = 'none'; document.getElementById('2305.10515v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">All figures and tables, along with any supplementary material and additional information, are available at http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-DP-2022-002.html (LHCb public pages)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-DP-2022-002 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> JINST 19 (2024) P05065 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.01442">arXiv:2210.01442</a> <span> [<a href="https://arxiv.org/pdf/2210.01442">pdf</a>, <a href="https://arxiv.org/format/2210.01442">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/18/02/P02011">10.1088/1748-0221/18/02/P02011 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Reconstruction of charged tracks with Timepix4 ASICs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K">Kazu Akiba</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">Martin van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=van+Beveren%2C+V">Vincent van Beveren</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">Wiktor Byczynski</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">Victor Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">Elena Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">Raphael Dumps</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">Tim Evans</a>, <a href="/search/physics?searchtype=author&query=Geertsema%2C+R">Robbert Geertsema</a>, <a href="/search/physics?searchtype=author&query=Gkougkousis%2C+E">Evangelios Gkougkousis</a>, <a href="/search/physics?searchtype=author&query=Halvorsen%2C+M">Marius Halvorsen</a>, <a href="/search/physics?searchtype=author&query=van+der+Heijden%2C+B">Bas van der Heijden</a>, <a href="/search/physics?searchtype=author&query=Heijhoff%2C+K">Kevin Heijhoff</a>, <a href="/search/physics?searchtype=author&query=Cid%2C+E+L">Edgar Lemos Cid</a>, <a href="/search/physics?searchtype=author&query=Pajero%2C+T">Tommaso Pajero</a>, <a href="/search/physics?searchtype=author&query=Rolf%2C+D">David Rolf</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">Heinrich Schindler</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.01442v2-abstract-short" style="display: inline;"> The design of a detector system comprised of four silicon sensors bump-bonded to Timepix4 ASICs is described together with its data acquisition system, operational infrastructure, and dedicated software. The spatial and temporal performance of the system are assessed with a 180 GeV/c mixed hadron beam at the CERN SPS and reported in detail. Particle tracks are reconstructed using time-space measur… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.01442v2-abstract-full').style.display = 'inline'; document.getElementById('2210.01442v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.01442v2-abstract-full" style="display: none;"> The design of a detector system comprised of four silicon sensors bump-bonded to Timepix4 ASICs is described together with its data acquisition system, operational infrastructure, and dedicated software. The spatial and temporal performance of the system are assessed with a 180 GeV/c mixed hadron beam at the CERN SPS and reported in detail. Particle tracks are reconstructed using time-space measurements from the four detector planes. The spatial hit resolution is assessed to be $(15.5\pm 0.5)$ $渭$m and $(4.5\pm0.3)$ $渭$m for 100 and 300 $渭$m thick sensors, respectively. The timestamps from the detectors are also measured with fine precision, yielding time resolutions of $(452\pm10)$ ps, $(420\pm10)$ ps, $(639\pm10)$ ps, $(631\pm10)$ ps for the two 100 and two 300 $渭$m thick sensors respectively. These measurements are combined to a track time resolution of $(340\pm 5)$ ps. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.01442v2-abstract-full').style.display = 'none'; document.getElementById('2210.01442v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 15 images in 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.01036">arXiv:2203.01036</a> <span> [<a href="https://arxiv.org/pdf/2203.01036">pdf</a>, <a href="https://arxiv.org/format/2203.01036">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2022.167325">10.1016/j.nima.2022.167325 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Silicon Electron Multiplier Sensor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Halvorsen%2C+M+M">Marius M忙hlum Halvorsen</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">Victor Coco</a>, <a href="/search/physics?searchtype=author&query=Gkougkousis%2C+E+L">Evangelos Leonidas Gkougkousis</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Girard%2C+O">Olivier Girard</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.01036v1-abstract-short" style="display: inline;"> The Silicon Electron Multiplier (SiEM) is a novel sensor concept for minimum ionizing particle (MIP) detection which uses internal gain and fine pitch to achieve excellent temporal and spatial resolution. In contrast to sensors where the gain region is induced by doping (LGADs, APDs), amplification in the SiEM is achieved by applying an electric potential difference in a composite electrode struct… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.01036v1-abstract-full').style.display = 'inline'; document.getElementById('2203.01036v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.01036v1-abstract-full" style="display: none;"> The Silicon Electron Multiplier (SiEM) is a novel sensor concept for minimum ionizing particle (MIP) detection which uses internal gain and fine pitch to achieve excellent temporal and spatial resolution. In contrast to sensors where the gain region is induced by doping (LGADs, APDs), amplification in the SiEM is achieved by applying an electric potential difference in a composite electrode structure embedded within the silicon bulk using MEMS fabrication techniques. Since no gain-layer deactivation is expected with radiation damage, such a structure is expected to withstand fluences of up to $10^{16} n_{eq}$. Various geometries and biasing configurations are studied, within the boundaries imposed by the fabrication process being considered. The effective gain, the field in the sensor, the leakage current and breakdown conditions are studied for cell sizes in the range of $6 - 15 渭m$. Simulations show that gains in excess of 10 can be achieved, and studies of the time structure of the induced signals from a charge cloud deposited in the middle of the sensor show that time resolutions similar to other sensors with internal gain can be expected. Plans for the manufacture of a proof-of-concept sensor and for its subsequent characterisation are discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.01036v1-abstract-full').style.display = 'none'; document.getElementById('2203.01036v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 21 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.12130">arXiv:2201.12130</a> <span> [<a href="https://arxiv.org/pdf/2201.12130">pdf</a>, <a href="https://arxiv.org/format/2201.12130">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/17/06/P06038">10.1088/1748-0221/17/06/P06038 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spatial resolution and efficiency of prototype sensors for the LHCb VELO Upgrade </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Buchanan%2C+E">E. Buchanan</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">E. Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">T. Evans</a>, <a href="/search/physics?searchtype=author&query=Lima%2C+V+F">V. Franco Lima</a>, <a href="/search/physics?searchtype=author&query=Geertsema%2C+R">R. Geertsema</a>, <a href="/search/physics?searchtype=author&query=Kopciewicz%2C+P">P. Kopciewicz</a>, <a href="/search/physics?searchtype=author&query=Price%2C+E">E. Price</a>, <a href="/search/physics?searchtype=author&query=Rachwal%2C+B">B. Rachwal</a>, <a href="/search/physics?searchtype=author&query=Richards%2C+S">S. Richards</a>, <a href="/search/physics?searchtype=author&query=Saunders%2C+D">D. Saunders</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">H. Schindler</a>, <a href="/search/physics?searchtype=author&query=Szumlak%2C+T">T. Szumlak</a>, <a href="/search/physics?searchtype=author&query=Tsopelas%2C+P">P. Tsopelas</a>, <a href="/search/physics?searchtype=author&query=Velthuis%2C+J">J. Velthuis</a>, <a href="/search/physics?searchtype=author&query=Williams%2C+M+R+J">M. R. J. Williams</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.12130v2-abstract-short" style="display: inline;"> A comprehensive study of the spatial resolution and detection efficiency of sensor prototypes developed for the LHCb VELO upgrade is presented. Data samples were collected at the CERN SPS H8 beam line using a hadron mixture of protons and pions with momenta of approximately 180 GeV/c. The sensor performance was characterised using both irradiated and non-irradiated sensors. Irradiated samples were… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.12130v2-abstract-full').style.display = 'inline'; document.getElementById('2201.12130v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.12130v2-abstract-full" style="display: none;"> A comprehensive study of the spatial resolution and detection efficiency of sensor prototypes developed for the LHCb VELO upgrade is presented. Data samples were collected at the CERN SPS H8 beam line using a hadron mixture of protons and pions with momenta of approximately 180 GeV/c. The sensor performance was characterised using both irradiated and non-irradiated sensors. Irradiated samples were subjected to a maximum fluence of $\mathrm{8\times10^{15}~1~MeV~n_{eq}~cm^{-2}}$, of both protons and neutrons. The spatial resolution is measured comparing the detected hits to the position as predicted by tracks reconstructed by the Timepix3 telescope. The resolution is presented for different applied bias voltages and track angles, sensor thickness and implant size. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.12130v2-abstract-full').style.display = 'none'; document.getElementById('2201.12130v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 15 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.13019">arXiv:2112.13019</a> <span> [<a href="https://arxiv.org/pdf/2112.13019">pdf</a>, <a href="https://arxiv.org/format/2112.13019">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> </div> <p class="title is-5 mathjax"> Tracking and Vertex detectors at FCC-ee </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Barchetta%2C+N">Nicola Barchetta</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Riedler%2C+P">Petra Riedler</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2112.13019v1-abstract-short" style="display: inline;"> The combined vertexing and tracking performance of the innermost part of the FCC-ee experiments must deliver outstanding precision for measurement of the track momentum together with an impact parameter resolution exceeding by at least a factor five that typically achieved at LHC experiments. Furthermore, precision measurements require stability and fiducial accuracy at a level which is unpreceden… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.13019v1-abstract-full').style.display = 'inline'; document.getElementById('2112.13019v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.13019v1-abstract-full" style="display: none;"> The combined vertexing and tracking performance of the innermost part of the FCC-ee experiments must deliver outstanding precision for measurement of the track momentum together with an impact parameter resolution exceeding by at least a factor five that typically achieved at LHC experiments. Furthermore, precision measurements require stability and fiducial accuracy at a level which is unprecedented in collider experiments. For the innermost vertex layers these goals translate into a target hit resolution of approximately 3 $渭$m together with a material budget of around 0.2\% of a radiation length per layer. Typically this performance might be provided by silicon-based tracking, together with a careful choice of a low-mass cooling technology, and a stable, low mass mechanical structure capable of providing measurements with a low enough systematic error to match the tremendous statistics expected, particularly for the run around the Z resonance. At FCC-ee, the magnetic field will be limited to approximately 2\,T, in order to contain the vertical emittance at the Z pole, and a tracking volume up to relative large radius is needed. The technological solution could be silicon or gaseous based tracking, in both cases with the focus on optimising the material budget, and particle identification capability would be an advantage. Depending on the global design, an additional silicon tracking layer could be added at the outer radius of the tracker to provide a final precise point contributing to the momentum or possibly time of flight measurement. Current developments in monolithic and hybrid silicon technology, as well as advanced gaseous tracking developments provide an encouraging road map towards the FCC-ee detector. The current state of the art and potential extensions will be discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.13019v1-abstract-full').style.display = 'none'; document.getElementById('2112.13019v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 17 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.12763">arXiv:2112.12763</a> <span> [<a href="https://arxiv.org/pdf/2112.12763">pdf</a>, <a href="https://arxiv.org/format/2112.12763">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2022.166874">10.1016/j.nima.2022.166874 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Microchannel cooling for the LHCb VELO Upgrade I </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Francisco%2C+O+A+D+A">Oscar Augusto De Aguiar Francisco</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">Wiktor Byczynski</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">Kazu Akiba</a>, <a href="/search/physics?searchtype=author&query=Bertella%2C+C">Claudia Bertella</a>, <a href="/search/physics?searchtype=author&query=Bitadze%2C+A">Alexander Bitadze</a>, <a href="/search/physics?searchtype=author&query=Brock%2C+M">Matthew Brock</a>, <a href="/search/physics?searchtype=author&query=Bulat%2C+B">Bartosz Bulat</a>, <a href="/search/physics?searchtype=author&query=Button%2C+G">Guillaume Button</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">Jan Buytaert</a>, <a href="/search/physics?searchtype=author&query=De+Capua%2C+S">Stefano De Capua</a>, <a href="/search/physics?searchtype=author&query=Callegari%2C+R">Riccardo Callegari</a>, <a href="/search/physics?searchtype=author&query=Castellana%2C+C">Christine Castellana</a>, <a href="/search/physics?searchtype=author&query=Catinaccio%2C+A">Andrea Catinaccio</a>, <a href="/search/physics?searchtype=author&query=Charrier%2C+C">Catherine Charrier</a>, <a href="/search/physics?searchtype=author&query=Charvet%2C+C">Collette Charvet</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">Victor Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Degrange%2C+J">Jordan Degrange</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">Raphael Dumps</a>, <a href="/search/physics?searchtype=author&query=Feito%2C+D+A">Diego Alvarez Feito</a>, <a href="/search/physics?searchtype=author&query=Freestone%2C+J">Julian Freestone</a>, <a href="/search/physics?searchtype=author&query=Jedrychowski%2C+M">Mariusz Jedrychowski</a>, <a href="/search/physics?searchtype=author&query=Lima%2C+V+F">Vinicius Franco Lima</a>, <a href="/search/physics?searchtype=author&query=Gallas%2C+A">Abraham Gallas</a>, <a href="/search/physics?searchtype=author&query=Hulsbergen%2C+W">Wouter Hulsbergen</a> , et al. (35 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2112.12763v1-abstract-short" style="display: inline;"> The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.12763v1-abstract-full').style.display = 'inline'; document.getElementById('2112.12763v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.12763v1-abstract-full" style="display: none;"> The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This paper describes the R\&D path supporting the microchannel production and assembly and the motivation for the design choices. The microchannel coolers have excellent thermal peformance, low and uniform mass, no thermal expansion mismatch with the ASICs and are radiation hard. The fluidic and thermal performance is presented. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.12763v1-abstract-full').style.display = 'none'; document.getElementById('2112.12763v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">31 pages, 27 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-PUB-2021-010 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.06088">arXiv:2102.06088</a> <span> [<a href="https://arxiv.org/pdf/2102.06088">pdf</a>, <a href="https://arxiv.org/format/2102.06088">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/16/07/P07035">10.1088/1748-0221/16/07/P07035 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Temporal characterisation of silicon sensors on Timepix3 ASICs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">Elena Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">Kazu Akiba</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">Martin van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Buchanan%2C+E">Emma Buchanan</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">Timothy Evans</a>, <a href="/search/physics?searchtype=author&query=Lima%2C+V+F">Vinicius Franco Lima</a>, <a href="/search/physics?searchtype=author&query=Geertsema%2C+R">Robbert Geertsema</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">Heinrich Schindler</a>, <a href="/search/physics?searchtype=author&query=Snoek%2C+H">Hella Snoek</a>, <a href="/search/physics?searchtype=author&query=Tsopelas%2C+P">Panagiotis Tsopelas</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.06088v2-abstract-short" style="display: inline;"> The timing performance of silicon sensors bump-bonded to Timepix3 ASICs is investigated, prior to and after different types of irradiation up to $8 \times 10^{15} 1 \mathrm{\,Me\kern -0.1em V} \mathrm{ \,n_{eq}} {\mathrm{ \,cm}}^{-2}$. The sensors have been tested with a beam of charged particles in two different configurations, perpendicular to and almost parallel to the incident beam. The second… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.06088v2-abstract-full').style.display = 'inline'; document.getElementById('2102.06088v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.06088v2-abstract-full" style="display: none;"> The timing performance of silicon sensors bump-bonded to Timepix3 ASICs is investigated, prior to and after different types of irradiation up to $8 \times 10^{15} 1 \mathrm{\,Me\kern -0.1em V} \mathrm{ \,n_{eq}} {\mathrm{ \,cm}}^{-2}$. The sensors have been tested with a beam of charged particles in two different configurations, perpendicular to and almost parallel to the incident beam. The second approach, known as the grazing angles method, is shown to be a powerful method to investigate not only the charge collection, but also the time-to-threshold properties as a function of the depth at which the charges are liberated. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.06088v2-abstract-full').style.display = 'none'; document.getElementById('2102.06088v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2021 JINST 16 P07035 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.10147">arXiv:2010.10147</a> <span> [<a href="https://arxiv.org/pdf/2010.10147">pdf</a>, <a href="https://arxiv.org/format/2010.10147">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/16/02/P02029">10.1088/1748-0221/16/02/P02029 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Charge collection properties of prototype sensors for the LHCb VELO upgrade </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Geertsema%2C+R">R. Geertsema</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Buchanan%2C+E">E. Buchanan</a>, <a href="/search/physics?searchtype=author&query=Burr%2C+C">C. Burr</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">W. Byczynski</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">E. Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">T. Evans</a>, <a href="/search/physics?searchtype=author&query=Lima%2C+V+F">V. Franco Lima</a>, <a href="/search/physics?searchtype=author&query=Heijhoff%2C+K">K. Heijhoff</a>, <a href="/search/physics?searchtype=author&query=Kopciewicz%2C+P">P. Kopciewicz</a>, <a href="/search/physics?searchtype=author&query=Marinho%2C+F">F. Marinho</a>, <a href="/search/physics?searchtype=author&query=Price%2C+E">E. Price</a>, <a href="/search/physics?searchtype=author&query=Rachwal%2C+B">B. Rachwal</a>, <a href="/search/physics?searchtype=author&query=Richards%2C+S">S. Richards</a>, <a href="/search/physics?searchtype=author&query=Saunders%2C+D">D. Saunders</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">H. Schindler</a>, <a href="/search/physics?searchtype=author&query=Snoek%2C+H">H. Snoek</a>, <a href="/search/physics?searchtype=author&query=Szumlak%2C+T">T. Szumlak</a>, <a href="/search/physics?searchtype=author&query=Tsopelas%2C+P">P. Tsopelas</a>, <a href="/search/physics?searchtype=author&query=Velthuis%2C+J">J. Velthuis</a>, <a href="/search/physics?searchtype=author&query=Williams%2C+M+R+J">M. R. J. Williams</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.10147v3-abstract-short" style="display: inline;"> An extensive sensor testing campaign is presented, dedicated to measuring the charge collection properties of prototype candidates for the Vertex Locator (VELO) detector for the upgraded LHCb experiment. The charge collection is measured with sensors exposed to fluences of up to $8 \times 10^{15}~1~\mathrm{\,Me\kern -0.1em V}~ \mathrm{ \,n_{eq}}~{\mathrm{ \,cm}}^{-2}$, as well as with nonirradiate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10147v3-abstract-full').style.display = 'inline'; document.getElementById('2010.10147v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.10147v3-abstract-full" style="display: none;"> An extensive sensor testing campaign is presented, dedicated to measuring the charge collection properties of prototype candidates for the Vertex Locator (VELO) detector for the upgraded LHCb experiment. The charge collection is measured with sensors exposed to fluences of up to $8 \times 10^{15}~1~\mathrm{\,Me\kern -0.1em V}~ \mathrm{ \,n_{eq}}~{\mathrm{ \,cm}}^{-2}$, as well as with nonirradiated prototypes. The results are discussed, including the influence of different levels of irradiation and bias voltage on the charge collection properties. Charge multiplication is observed on some sensors that were nonuniformly irradiated with 24 GeV protons, to the highest fluence levels. An analysis of the charge collection near the guard ring region is also presented, revealing significant differences between the sensor prototypes. All tested sensor variants succeed in collecting the minimum required charge of 6000 electrons after the exposure to the maximum fluence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10147v3-abstract-full').style.display = 'none'; document.getElementById('2010.10147v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.04801">arXiv:2008.04801</a> <span> [<a href="https://arxiv.org/pdf/2008.04801">pdf</a>, <a href="https://arxiv.org/format/2008.04801">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/15/09/P09035">10.1088/1748-0221/15/09/P09035 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Timing performance of the LHCb VELO Timepix3 Telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Heijhoff%2C+K">K. Heijhoff</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Bosch%2C+P">P. Bosch</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Campbell%2C+M">M. Campbell</a>, <a href="/search/physics?searchtype=author&query=Colijn%2C+A+P">A. P. Colijn</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">E. Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">T. Evans</a>, <a href="/search/physics?searchtype=author&query=Geertsema%2C+R">R. Geertsema</a>, <a href="/search/physics?searchtype=author&query=Heidotting%2C+M+L+E">M. L. E. Heidotting</a>, <a href="/search/physics?searchtype=author&query=Hynds%2C+D">D. Hynds</a>, <a href="/search/physics?searchtype=author&query=Cudie%2C+X+L">X. Llopart Cudie</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">H. Schindler</a>, <a href="/search/physics?searchtype=author&query=Snoek%2C+H">H. Snoek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.04801v1-abstract-short" style="display: inline;"> We performed a detailed study of the timing performance of the LHCb VELO Timepix3 Telescope with a 180 GeV/c mixed hadron beam at the CERN SPS. A twofold method was developed to improve the resolution of single-plane time measurements, resulting in a more precise overall track time measurement. The first step uses spatial information of reconstructed tracks in combination with the measured signal… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.04801v1-abstract-full').style.display = 'inline'; document.getElementById('2008.04801v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.04801v1-abstract-full" style="display: none;"> We performed a detailed study of the timing performance of the LHCb VELO Timepix3 Telescope with a 180 GeV/c mixed hadron beam at the CERN SPS. A twofold method was developed to improve the resolution of single-plane time measurements, resulting in a more precise overall track time measurement. The first step uses spatial information of reconstructed tracks in combination with the measured signal charge in the sensor to correct for a mixture of different effects: variations in charge carrier drift time; variations in signal induction, which are the result of a non-uniform weighting field in the pixels; and lastly, timewalk in the analog front-end. The second step corrects for systematic timing offsets in Timepix3 that vary from -2 ns to 2 ns. By applying this method, we improved the track time resolution from 438$\,\pm\,$16 ps to 276$\,\pm\,$4 ps. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.04801v1-abstract-full').style.display = 'none'; document.getElementById('2008.04801v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.12012">arXiv:2007.12012</a> <span> [<a href="https://arxiv.org/pdf/2007.12012">pdf</a>, <a href="https://arxiv.org/format/2007.12012">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Medical Physics">physics.med-ph</span> </div> </div> <p class="title is-5 mathjax"> The HEV Ventilator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Abud%2C+A+A">A. Abed Abud</a>, <a href="/search/physics?searchtype=author&query=Allport%2C+P">P. Allport</a>, <a href="/search/physics?searchtype=author&query=%C3%81lvarez%2C+A+P">A. Pazos 脕lvarez</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Francisco%2C+O+A+d+A">O. Augusto de Aguiar Francisco</a>, <a href="/search/physics?searchtype=author&query=Bay%2C+A">A. Bay</a>, <a href="/search/physics?searchtype=author&query=Bernard%2C+F">F. Bernard</a>, <a href="/search/physics?searchtype=author&query=Baron%2C+S">S. Baron</a>, <a href="/search/physics?searchtype=author&query=Bertella%2C+C">C. Bertella</a>, <a href="/search/physics?searchtype=author&query=Brunner%2C+J">J. Brunner</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T">T. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Jode%2C+M+B">M. Buytaert-De Jode</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">W. Byczynski</a>, <a href="/search/physics?searchtype=author&query=De+Carvalho%2C+R">R. De Carvalho</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+R">R. Collins</a>, <a href="/search/physics?searchtype=author&query=Dikic%2C+N">N. Dikic</a>, <a href="/search/physics?searchtype=author&query=Dousse%2C+N">N. Dousse</a>, <a href="/search/physics?searchtype=author&query=Dowd%2C+B">B. Dowd</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a>, <a href="/search/physics?searchtype=author&query=Durante%2C+P">P. Durante</a>, <a href="/search/physics?searchtype=author&query=Fadel%2C+W">W. Fadel</a>, <a href="/search/physics?searchtype=author&query=Farry%2C+S">S. Farry</a> , et al. (49 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.12012v1-abstract-short" style="display: inline;"> HEV is a low-cost, versatile, high-quality ventilator, which has been designed in response to the COVID-19 pandemic. The ventilator is intended to be used both in and out of hospital intensive care units, and for both invasive and non-invasive ventilation. The hardware can be complemented with an external turbine for use in regions where compressed air supplies are not reliably available. The stan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.12012v1-abstract-full').style.display = 'inline'; document.getElementById('2007.12012v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.12012v1-abstract-full" style="display: none;"> HEV is a low-cost, versatile, high-quality ventilator, which has been designed in response to the COVID-19 pandemic. The ventilator is intended to be used both in and out of hospital intensive care units, and for both invasive and non-invasive ventilation. The hardware can be complemented with an external turbine for use in regions where compressed air supplies are not reliably available. The standard modes provided include PC-A/C(Pressure Assist Control),PC-A/C-PRVC(Pressure Regulated Volume Control), PC-PSV (Pressure Support Ventilation) and CPAP (Continuous Positive airway pressure). HEV is designed to support remote training and post market surveillance via a web interface and data logging to complement the standard touch screen operation, making it suitable for a wide range of geographical deployment. The HEV design places emphasis on the quality of the pressure curves and the reactivity of the trigger, delivering a global performance which will be applicable to ventilator needs beyond theCOVID-19 pandemic. This article describes the conceptual design and presents the prototype units together with their performance evaluation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.12012v1-abstract-full').style.display = 'none'; document.getElementById('2007.12012v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 18 figures, Extended version of the article submitted to PNAS</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-TECH-NOTE-2020-002 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.09559">arXiv:2006.09559</a> <span> [<a href="https://arxiv.org/pdf/2006.09559">pdf</a>, <a href="https://arxiv.org/format/2006.09559">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/15/06/C06009">10.1088/1748-0221/15/06/C06009 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Upgrade I of LHCb VELO -- towards an intelligent monitoring platform </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kopciewicz%2C+P">P. Kopciewicz</a>, <a href="/search/physics?searchtype=author&query=Szumlak%2C+T">T. Szumlak</a>, <a href="/search/physics?searchtype=author&query=Majewski%2C+M">M. Majewski</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Augusto%2C+O">O. Augusto</a>, <a href="/search/physics?searchtype=author&query=Back%2C+J">J. Back</a>, <a href="/search/physics?searchtype=author&query=Bobulska%2C+D+S">D. S. Bobulska</a>, <a href="/search/physics?searchtype=author&query=Bogdanova%2C+G">G. Bogdanova</a>, <a href="/search/physics?searchtype=author&query=Borghi%2C+S">S. Borghi</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T">T. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Cid%2C+E+L">E. Lemos Cid</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">E. Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=de+Bruyn%2C+K">K. de Bruyn</a>, <a href="/search/physics?searchtype=author&query=de+Capua%2C+S">S. de Capua</a>, <a href="/search/physics?searchtype=author&query=Dettori%2C+F">F. Dettori</a>, <a href="/search/physics?searchtype=author&query=Dreimanis%2C+K">K. Dreimanis</a>, <a href="/search/physics?searchtype=author&query=Dutta%2C+D">D. Dutta</a>, <a href="/search/physics?searchtype=author&query=Eklund%2C+L">L. Eklund</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">T. Evans</a>, <a href="/search/physics?searchtype=author&query=Funk%2C+M+F+W">M. Ferro-Luzzi W. Funk</a>, <a href="/search/physics?searchtype=author&query=Garcia%2C+L+M">L. Meyer Garcia</a>, <a href="/search/physics?searchtype=author&query=Garc%C3%ADa%2C+O+B">O. Boente Garc铆a</a> , et al. (41 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.09559v2-abstract-short" style="display: inline;"> The Large Hadron Collider beauty (LHCb) detector is designed to detect decays of b- and c- hadrons for the study of CP violation and rare decays. At the end of the LHC Run 2, many of the LHCb measurements remained statistically dominated. In order to increase the trigger yield for purely hadronic channels, the hardware trigger will be removed, and the detector will be read out at 40 MHz. This, in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.09559v2-abstract-full').style.display = 'inline'; document.getElementById('2006.09559v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.09559v2-abstract-full" style="display: none;"> The Large Hadron Collider beauty (LHCb) detector is designed to detect decays of b- and c- hadrons for the study of CP violation and rare decays. At the end of the LHC Run 2, many of the LHCb measurements remained statistically dominated. In order to increase the trigger yield for purely hadronic channels, the hardware trigger will be removed, and the detector will be read out at 40 MHz. This, in combination with the five-fold increase in luminosity, requires radical changes to LHCb's electronics, and, in some cases, the replacement of entire sub-detectors with state-of-the-art detector technologies. The Vertex Locator (VELO) surrounding the interaction region is used to reconstruct the collision points (primary vertices) and decay vertices of long-lived particles (secondary vertices). The upgraded VELO will be composed of 52 modules placed along the beam axis divided into two retractable halves. The modules will each be equipped with 4 silicon hybrid pixel tiles, each read out by 3 VeloPix ASICs. The total output data rate anticipated for the whole detector will be around 1.6 Tbit/s. The highest occupancy ASICs will have pixel hit rates of approximately 900 Mhit/s, with the corresponding output data rate of 15 Gbit/s. The LHCb upgrade detector will be the first detector to read out at the full LHC rate of 40 MHz. The VELO upgrade will utilize the latest detector technologies to read out at this rate while maintaining the required radiation-hard profile and minimizing the detector material. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.09559v2-abstract-full').style.display = 'none'; document.getElementById('2006.09559v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Journal of Instrumentation (JINST), Volume 15, June 2020 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2004.00534">arXiv:2004.00534</a> <span> [<a href="https://arxiv.org/pdf/2004.00534">pdf</a>, <a href="https://arxiv.org/format/2004.00534">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Medical Physics">physics.med-ph</span> </div> </div> <p class="title is-5 mathjax"> The HEV Ventilator Proposal </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Abud%2C+A+A">A. Abed Abud</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Bay%2C+A">A. Bay</a>, <a href="/search/physics?searchtype=author&query=Bertella%2C+C">C. Bertella</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T">T. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">W. Byczynski</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Francisco%2C+O+A+D+A">O. Augusto De Aguiar Francisco</a>, <a href="/search/physics?searchtype=author&query=Dikic%2C+N">N. Dikic</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a>, <a href="/search/physics?searchtype=author&query=Durante%2C+P">P. Durante</a>, <a href="/search/physics?searchtype=author&query=Prieto%2C+A+F">A. Fern谩ndez Prieto</a>, <a href="/search/physics?searchtype=author&query=Lima%2C+V+F">V. Franco Lima</a>, <a href="/search/physics?searchtype=author&query=Guida%2C+R">R. Guida</a>, <a href="/search/physics?searchtype=author&query=Hennessy%2C+K">K. Hennessy</a>, <a href="/search/physics?searchtype=author&query=Hutchcroft%2C+D">D. Hutchcroft</a>, <a href="/search/physics?searchtype=author&query=Ilic%2C+S">S. Ilic</a>, <a href="/search/physics?searchtype=author&query=Jevtic%2C+A">A. Jevtic</a>, <a href="/search/physics?searchtype=author&query=Kapusniak%2C+K">K. Kapusniak</a>, <a href="/search/physics?searchtype=author&query=Cid%2C+E+L">E. Lemos Cid</a>, <a href="/search/physics?searchtype=author&query=Lindner%2C+J">J. Lindner</a>, <a href="/search/physics?searchtype=author&query=Milovanovic%2C+M">M. Milovanovic</a>, <a href="/search/physics?searchtype=author&query=Murray%2C+D">D. Murray</a> , et al. (6 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2004.00534v2-abstract-short" style="display: inline;"> We propose the design of a ventilator which can be easily manufactured and integrated into the hospital environment to support COVID-19 patients. The unit is designed to support standard ventilator modes of operation, most importantly PRVC (Pressure Regulated Volume Control) and SIMV-PC (Synchronised Intermittent Mandatory Ventilation) modes. The unit is not yet an approved medical device and is i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.00534v2-abstract-full').style.display = 'inline'; document.getElementById('2004.00534v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2004.00534v2-abstract-full" style="display: none;"> We propose the design of a ventilator which can be easily manufactured and integrated into the hospital environment to support COVID-19 patients. The unit is designed to support standard ventilator modes of operation, most importantly PRVC (Pressure Regulated Volume Control) and SIMV-PC (Synchronised Intermittent Mandatory Ventilation) modes. The unit is not yet an approved medical device and is in the concept and prototyping stage. It is presented here to invite fast feedback for development and deployment in the face of the COVID-19 pandemic. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.00534v2-abstract-full').style.display = 'none'; document.getElementById('2004.00534v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-TECH-NOTE-2020-01 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.13146">arXiv:1904.13146</a> <span> [<a href="https://arxiv.org/pdf/1904.13146">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-019-13629-w">10.1038/s41467-019-13629-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of strong nonlinear interactions in parametric down-conversion of x-rays into ultraviolet radiation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sofer%2C+S">S. Sofer</a>, <a href="/search/physics?searchtype=author&query=Sefi%2C+O">O. Sefi</a>, <a href="/search/physics?searchtype=author&query=Strizhevsky%2C+E">E. Strizhevsky</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+S+P">S. P. Collins</a>, <a href="/search/physics?searchtype=author&query=Detlefs%2C+B">B. Detlefs</a>, <a href="/search/physics?searchtype=author&query=Sahle%2C+C+J">Ch. J. Sahle</a>, <a href="/search/physics?searchtype=author&query=Shwartz%2C+S">S. Shwartz</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1904.13146v1-abstract-short" style="display: inline;"> Nonlinear interactions between x-rays and long wavelengths can be used as a powerful atomic scale probe for light-matter interactions and for properties of valence electrons. This probe can provide novel microscopic information in solids that existing methods cannot reveal, hence to advance the understanding of many phenomena in condensed matter physics. However, thus far, reported x-ray nonlinear… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.13146v1-abstract-full').style.display = 'inline'; document.getElementById('1904.13146v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.13146v1-abstract-full" style="display: none;"> Nonlinear interactions between x-rays and long wavelengths can be used as a powerful atomic scale probe for light-matter interactions and for properties of valence electrons. This probe can provide novel microscopic information in solids that existing methods cannot reveal, hence to advance the understanding of many phenomena in condensed matter physics. However, thus far, reported x-ray nonlinear effects were very small and their observations required tremendous efforts. Here we report the observation of unexpected strong nonlinearities in parametric down-conversion (PDC) of x-rays to long wavelengths in gallium arsenide (GaAs) and in lithium niobate (LiNbO3) crystals, with efficiencies that are about 4 orders of magnitude stronger than the efficiencies measured in any material studied before. These strong nonlinearities cannot be explained by any known theory and indicate on possibilities for the development of a new spectroscopy method that is orbital and band selective. In this work we demonstrate the ability to use PDC of x-rays to investigate the spectral response of materials in a very broad range of wavelengths from the infrared regime to the soft x-ray regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.13146v1-abstract-full').style.display = 'none'; document.getElementById('1904.13146v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">31 pages, 10 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.09755">arXiv:1902.09755</a> <span> [<a href="https://arxiv.org/pdf/1902.09755">pdf</a>, <a href="https://arxiv.org/format/1902.09755">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/14/05/P05026">10.1088/1748-0221/14/05/P05026 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> LHCb VELO Timepix3 Telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K">Kazu Akiba</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">Martin van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Boterenbrood%2C+H">Henk Boterenbrood</a>, <a href="/search/physics?searchtype=author&query=Buchanan%2C+E">Emma Buchanan</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">Jan Buytaert</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">Wiktor Byczynski</a>, <a href="/search/physics?searchtype=author&query=Vidal%2C+X+C">Xabier Cid Vidal</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">Elena Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=Suarez%2C+A+D">Alvaro Dosil Suarez</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">Raphael Dumps</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">Tim Evans</a>, <a href="/search/physics?searchtype=author&query=Lima%2C+V+F">Vinicius Franco Lima</a>, <a href="/search/physics?searchtype=author&query=Torreira%2C+A+G">Abraham Gallas Torreira</a>, <a href="/search/physics?searchtype=author&query=Pardinas%2C+J+G">Julian Garcia Pardinas</a>, <a href="/search/physics?searchtype=author&query=van+der+Heijden%2C+B">Bas van der Heijden</a>, <a href="/search/physics?searchtype=author&query=Hombach%2C+C">Christoph Hombach</a>, <a href="/search/physics?searchtype=author&query=John%2C+M">Malcolm John</a>, <a href="/search/physics?searchtype=author&query=Kulis%2C+S">Szymon Kulis</a>, <a href="/search/physics?searchtype=author&query=Cudie%2C+X+L">Xavi Llopart Cudie</a>, <a href="/search/physics?searchtype=author&query=Marinho%2C+F">Franciole Marinho</a>, <a href="/search/physics?searchtype=author&query=Price%2C+E">Eugenia Price</a>, <a href="/search/physics?searchtype=author&query=Richards%2C+S">Sophie Richards</a>, <a href="/search/physics?searchtype=author&query=Perez%2C+P+R">Pablo Rodriguez Perez</a>, <a href="/search/physics?searchtype=author&query=Saunders%2C+D">Daniel Saunders</a> , et al. (8 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1902.09755v1-abstract-short" style="display: inline;"> The LHCb VELO Timepix3 telescope is a silicon pixel tracking system constructed initially to evaluate the performance of LHCb VELO Upgrade prototypes. The telesope consists of eight hybrid pixel silicon sensor planes equipped with the Timepix3 ASIC. The planes provide excellent charge measurement, timestamping and spatial resolution and the system can function at high track rates. This paper descr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.09755v1-abstract-full').style.display = 'inline'; document.getElementById('1902.09755v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.09755v1-abstract-full" style="display: none;"> The LHCb VELO Timepix3 telescope is a silicon pixel tracking system constructed initially to evaluate the performance of LHCb VELO Upgrade prototypes. The telesope consists of eight hybrid pixel silicon sensor planes equipped with the Timepix3 ASIC. The planes provide excellent charge measurement, timestamping and spatial resolution and the system can function at high track rates. This paper describes the construction of the telescope and its data acquisition system and offline reconstruction software. A timing resolution of 350~ps was obtained for reconstructed tracks. A pointing resolution of better than 2~\mum was determined for the 180~GeV/c %\gevc mixed hadron beam at the CERN SPS. The telescope has been shown to operate at a rate of 5 million particles~\unit{s^{-1}\cdot cm^{-2}} without a loss in efficiency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.09755v1-abstract-full').style.display = 'none'; document.getElementById('1902.09755v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.09216">arXiv:1810.09216</a> <span> [<a href="https://arxiv.org/pdf/1810.09216">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.99.054428">10.1103/PhysRevB.99.054428 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Superchiral photons unveil magnetic circular dichroism </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Lovesey%2C+S+W">S. W. Lovesey</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+J+T">J. T. Collins</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+S+P">S. P. Collins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.09216v1-abstract-short" style="display: inline;"> Polarization-dependent photon spectroscopy (dichroism) using signal-enhancing superchiral beams is shown to be sensitive to magnetic properties of the sample, whereas previous investigations explored charge-like electronic properties of chiral samples. In the process of unveiling the potential to observe magnetic circular dichroism (MCD), we underline an affinity between spectroscopies using the B… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.09216v1-abstract-full').style.display = 'inline'; document.getElementById('1810.09216v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.09216v1-abstract-full" style="display: none;"> Polarization-dependent photon spectroscopy (dichroism) using signal-enhancing superchiral beams is shown to be sensitive to magnetic properties of the sample, whereas previous investigations explored charge-like electronic properties of chiral samples. In the process of unveiling the potential to observe magnetic circular dichroism (MCD), we underline an affinity between spectroscopies using the Borrmann effect, twisted beams and superchiral beams. Use of an effective wavevector in a quantum-mechanical theory unites the aforementioned spectroscopies and vastly improves our understanding of their advantages. Exploiting an effective wavevector for superchiral beams, natural circular dichroism (NCD) is derived from electric dipole - magnetic dipole (E1-M1) and electric dipole - electric quadrupole (E1-E2) absorption events, and MCD is derived from electric quadrupole-electric quadrupole (E2-E2) absorption. Signal enhancement by superchiral beams is a straightforward gain for the user because NCD and MCD are otherwise precisely the same as for a circularly polarized beam, according to our calculations. Our analysis shows that enhancement of E2-E2 is superior to that available for parity-odd events under consideration. Electronic degrees of freedom in all dichroic signals are encapsulated in atomic multipoles that are frequently used in theoretical interpretations of several established experimental techniques. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.09216v1-abstract-full').style.display = 'none'; document.getElementById('1810.09216v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 99, 054428 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.07466">arXiv:1803.07466</a> <span> [<a href="https://arxiv.org/pdf/1803.07466">pdf</a>, <a href="https://arxiv.org/format/1803.07466">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/13/06/P06008">10.1088/1748-0221/13/06/P06008 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Mapping the material in the LHCb vertex locator using secondary hadronic interactions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Alexander%2C+M">M. Alexander</a>, <a href="/search/physics?searchtype=author&query=Barter%2C+W">W. Barter</a>, <a href="/search/physics?searchtype=author&query=Bay%2C+A">A. Bay</a>, <a href="/search/physics?searchtype=author&query=Bel%2C+L+J">L. J. Bel</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Bogdanova%2C+G">G. Bogdanova</a>, <a href="/search/physics?searchtype=author&query=Borghi%2C+S">S. Borghi</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T+J+V">T. J. V. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Buchanan%2C+E">E. Buchanan</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K+C">K. Carvalho Akiba</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+S">S. Chen</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Crocombe%2C+A">A. Crocombe</a>, <a href="/search/physics?searchtype=author&query=Marinho%2C+F+D+C">F. Da Cunha Marinho</a>, <a href="/search/physics?searchtype=author&query=Dall%27Occo%2C+E">E. Dall'Occo</a>, <a href="/search/physics?searchtype=author&query=De+Capua%2C+S">S. De Capua</a>, <a href="/search/physics?searchtype=author&query=Dean%2C+C+T">C. T. Dean</a>, <a href="/search/physics?searchtype=author&query=Dettori%2C+F">F. Dettori</a>, <a href="/search/physics?searchtype=author&query=Dossett%2C+D">D. Dossett</a>, <a href="/search/physics?searchtype=author&query=Dreimanis%2C+K">K. Dreimanis</a>, <a href="/search/physics?searchtype=author&query=Dujany%2C+G">G. Dujany</a>, <a href="/search/physics?searchtype=author&query=Eklund%2C+L">L. Eklund</a>, <a href="/search/physics?searchtype=author&query=Evans%2C+T">T. Evans</a> , et al. (41 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.07466v2-abstract-short" style="display: inline;"> Precise knowledge of the location of the material in the LHCb vertex locator (VELO) is essential to reducing background in searches for long-lived exotic particles, and in identifying jets that originate from beauty and charm quarks. Secondary interactions of hadrons produced in beam-gas collisions are used to map the location of material in the VELO. Using this material map, along with properties… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.07466v2-abstract-full').style.display = 'inline'; document.getElementById('1803.07466v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.07466v2-abstract-full" style="display: none;"> Precise knowledge of the location of the material in the LHCb vertex locator (VELO) is essential to reducing background in searches for long-lived exotic particles, and in identifying jets that originate from beauty and charm quarks. Secondary interactions of hadrons produced in beam-gas collisions are used to map the location of material in the VELO. Using this material map, along with properties of a reconstructed secondary vertex and its constituent tracks, a $p$-value can be assigned to the hypothesis that the secondary vertex originates from a material interaction. A validation of this procedure is presented using photon conversions to dimuons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.07466v2-abstract-full').style.display = 'none'; document.getElementById('1803.07466v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">All figures and tables are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-DP-2018-002.html</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-LHCb-DP-2018-002 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> JINST 13, P06008 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1801.04281">arXiv:1801.04281</a> <span> [<a href="https://arxiv.org/pdf/1801.04281">pdf</a>, <a href="https://arxiv.org/format/1801.04281">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/13/04/P04017">10.1088/1748-0221/13/04/P04017 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The HeRSCheL detector: high-rapidity shower counters for LHCb </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K+C">K. Carvalho Akiba</a>, <a href="/search/physics?searchtype=author&query=Alessio%2C+F">F. Alessio</a>, <a href="/search/physics?searchtype=author&query=Bondar%2C+N">N. Bondar</a>, <a href="/search/physics?searchtype=author&query=Byczynski%2C+W">W. Byczynski</a>, <a href="/search/physics?searchtype=author&query=Coco%2C+V">V. Coco</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a>, <a href="/search/physics?searchtype=author&query=Dzhelyadin%2C+R">R. Dzhelyadin</a>, <a href="/search/physics?searchtype=author&query=Gandini%2C+P">P. Gandini</a>, <a href="/search/physics?searchtype=author&query=Cazon%2C+B+R+G">B. R. Gruberg Cazon</a>, <a href="/search/physics?searchtype=author&query=Jacobsson%2C+R">R. Jacobsson</a>, <a href="/search/physics?searchtype=author&query=Johnson%2C+D">D. Johnson</a>, <a href="/search/physics?searchtype=author&query=Manthey%2C+J">J. Manthey</a>, <a href="/search/physics?searchtype=author&query=Mauricio%2C+J">J. Mauricio</a>, <a href="/search/physics?searchtype=author&query=McNulty%2C+R">R. McNulty</a>, <a href="/search/physics?searchtype=author&query=Monteil%2C+S">S. Monteil</a>, <a href="/search/physics?searchtype=author&query=Rachwal%2C+B">B. Rachwal</a>, <a href="/search/physics?searchtype=author&query=Salzgeber%2C+M+R">M. Ravonel Salzgeber</a>, <a href="/search/physics?searchtype=author&query=Roy%2C+L">L. Roy</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">H. Schindler</a>, <a href="/search/physics?searchtype=author&query=Stevenson%2C+S">S. Stevenson</a>, <a href="/search/physics?searchtype=author&query=Wilkinson%2C+G">G. Wilkinson</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1801.04281v2-abstract-short" style="display: inline;"> The HeRSCheL detector consists of a set of scintillating counters, designed to increase the coverage of the LHCb experiment in the high-rapidity regions on either side of the main spectrometer. The new detector improves the capabilities of LHCb for studies of diffractive interactions, most notably Central Exclusive Production. In this paper the construction, installation, commissioning, and perfor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.04281v2-abstract-full').style.display = 'inline'; document.getElementById('1801.04281v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1801.04281v2-abstract-full" style="display: none;"> The HeRSCheL detector consists of a set of scintillating counters, designed to increase the coverage of the LHCb experiment in the high-rapidity regions on either side of the main spectrometer. The new detector improves the capabilities of LHCb for studies of diffractive interactions, most notably Central Exclusive Production. In this paper the construction, installation, commissioning, and performance of HeRSCheL are presented. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.04281v2-abstract-full').style.display = 'none'; document.getElementById('1801.04281v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 January, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">New version to match published text. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-DP-2016-003.html</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-DP-2016-003 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> JINST 13 (2018) no.04, P04017 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1511.08919">arXiv:1511.08919</a> <span> [<a href="https://arxiv.org/pdf/1511.08919">pdf</a>, <a href="https://arxiv.org/format/1511.08919">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.4940798">10.1063/1.4940798 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phase space barriers and dividing surfaces in the absence of critical points of the potential energy: Application to roaming in ozone </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Maugui%C3%A8re%2C+F+A+L">Fr茅d茅ric A. L. Maugui猫re</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Kramer%2C+Z+C">Zeb C. Kramer</a>, <a href="/search/physics?searchtype=author&query=Carpenter%2C+B+K">Barry K. Carpenter</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Farantos%2C+S+C">Stavros C. Farantos</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1511.08919v1-abstract-short" style="display: inline;"> We examine the phase space structures that govern reaction dynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori it is possible to define phase space dividing surfaces that are analogous to the dividing surfaces governing transition from reactants to products near a critical point of the potential energy surface. We in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.08919v1-abstract-full').style.display = 'inline'; document.getElementById('1511.08919v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.08919v1-abstract-full" style="display: none;"> We examine the phase space structures that govern reaction dynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori it is possible to define phase space dividing surfaces that are analogous to the dividing surfaces governing transition from reactants to products near a critical point of the potential energy surface. We investigate the problem of capture of an atom by a diatomic molecule and show that a normally hyperbolic invariant manifold exists at large atom-diatom distances, away from any critical points on the potential. This normally hyperbolic invariant manifold is the anchor for the construction of a dividing surface in phase space, which defines the outer or loose transition state governing capture dynamics. We present an algorithm for sampling an approximate capture dividing surface, and apply our methods to the recombination of the ozone molecule. We treat both 2 and 3 degree of freedom models with zero total angular momentum. We have located the normally hyperbolic invariant manifold from which the orbiting (outer) transition state is constructed. This forms the basis for our analysis of trajectories for ozone in general, but with particular emphasis on the roaming trajectories. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.08919v1-abstract-full').style.display = 'none'; document.getElementById('1511.08919v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 November, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">35 pages, 3 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1509.02387">arXiv:1509.02387</a> <span> [<a href="https://arxiv.org/pdf/1509.02387">pdf</a>, <a href="https://arxiv.org/format/1509.02387">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/11/01/P01011">10.1088/1748-0221/11/01/P01011 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterisation of Medipix3 Silicon Detectors in a Charged-Particle Beam </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Aoude%2C+R">R. Aoude</a>, <a href="/search/physics?searchtype=author&query=Alozy%2C+J">J. Alozy</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Su%C3%A1rez%2C+A+D">A. Dosil Su谩rez</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a>, <a href="/search/physics?searchtype=author&query=Gallas%2C+A">A. Gallas</a>, <a href="/search/physics?searchtype=author&query=Hombach%2C+C">C. Hombach</a>, <a href="/search/physics?searchtype=author&query=Hynds%2C+D">D. Hynds</a>, <a href="/search/physics?searchtype=author&query=John%2C+M">M. John</a>, <a href="/search/physics?searchtype=author&query=Leflat%2C+A">A. Leflat</a>, <a href="/search/physics?searchtype=author&query=Li%2C+Y">Y. Li</a>, <a href="/search/physics?searchtype=author&query=Trigo%2C+E+P">E. P茅rez Trigo</a>, <a href="/search/physics?searchtype=author&query=Plackett%2C+R">R. Plackett</a>, <a href="/search/physics?searchtype=author&query=Reid%2C+M+M">M. M. Reid</a>, <a href="/search/physics?searchtype=author&query=P%C3%A9rez%2C+P+R">P. Rodr铆guez P茅rez</a>, <a href="/search/physics?searchtype=author&query=Schindler%2C+H">H. Schindler</a>, <a href="/search/physics?searchtype=author&query=Tsopelas%2C+P">P. Tsopelas</a>, <a href="/search/physics?searchtype=author&query=Sierra%2C+C+V">C. V谩zquez Sierra</a>, <a href="/search/physics?searchtype=author&query=Velthuis%2C+J+J">J. J. Velthuis</a>, <a href="/search/physics?searchtype=author&query=Wysoki%C5%84ski%2C+M">M. Wysoki艅ski</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1509.02387v2-abstract-short" style="display: inline;"> While designed primarily for X-ray imaging applications, the Medipix3 ASIC can also be used for charged-particle tracking. In this work, results from a beam test at the CERN SPS with irradiated and non-irradiated sensors are presented and shown to be in agreement with simulation, demonstrating the suitability of the Medipix3 ASIC as a tool for characterising pixel sensors. </span> <span class="abstract-full has-text-grey-dark mathjax" id="1509.02387v2-abstract-full" style="display: none;"> While designed primarily for X-ray imaging applications, the Medipix3 ASIC can also be used for charged-particle tracking. In this work, results from a beam test at the CERN SPS with irradiated and non-irradiated sensors are presented and shown to be in agreement with simulation, demonstrating the suitability of the Medipix3 ASIC as a tool for characterising pixel sensors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.02387v2-abstract-full').style.display = 'none'; document.getElementById('1509.02387v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 January, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 13 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-PUB-2016-002 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> JINST 11 (2016) P01011 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1405.7808">arXiv:1405.7808</a> <span> [<a href="https://arxiv.org/pdf/1405.7808">pdf</a>, <a href="https://arxiv.org/format/1405.7808">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/9/09/P09007">10.1088/1748-0221/9/09/P09007 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Performance of the LHCb Vertex Locator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=LHCb+VELO+Group"> LHCb VELO Group</a>, <a href="/search/physics?searchtype=author&query=Aaij%2C+R">R. Aaij</a>, <a href="/search/physics?searchtype=author&query=Affolder%2C+A">A. Affolder</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Alexander%2C+M">M. Alexander</a>, <a href="/search/physics?searchtype=author&query=Ali%2C+S">S. Ali</a>, <a href="/search/physics?searchtype=author&query=Appleby%2C+R+B">R. B. Appleby</a>, <a href="/search/physics?searchtype=author&query=Artuso%2C+M">M. Artuso</a>, <a href="/search/physics?searchtype=author&query=Bates%2C+A">A. Bates</a>, <a href="/search/physics?searchtype=author&query=Bay%2C+A">A. Bay</a>, <a href="/search/physics?searchtype=author&query=Behrendt%2C+O">O. Behrendt</a>, <a href="/search/physics?searchtype=author&query=Benton%2C+J">J. Benton</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Bj%C3%B8rnstad%2C+P+M">P. M. Bj酶rnstad</a>, <a href="/search/physics?searchtype=author&query=Bogdanova%2C+G">G. Bogdanova</a>, <a href="/search/physics?searchtype=author&query=Borghi%2C+S">S. Borghi</a>, <a href="/search/physics?searchtype=author&query=Borgia%2C+A">A. Borgia</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T+J+V">T. J. V. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Brand%2C+J+v+d">J. van den Brand</a>, <a href="/search/physics?searchtype=author&query=Brown%2C+H">H. Brown</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Callot%2C+O">O. Callot</a>, <a href="/search/physics?searchtype=author&query=Carroll%2C+J">J. Carroll</a>, <a href="/search/physics?searchtype=author&query=Casse%2C+G">G. Casse</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a> , et al. (79 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1405.7808v2-abstract-short" style="display: inline;"> The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stabi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1405.7808v2-abstract-full').style.display = 'inline'; document.getElementById('1405.7808v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1405.7808v2-abstract-full" style="display: none;"> The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 microns is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means that the inner regions of the n+-on-n sensors have undergone space-charge sign inversion due to radiation damage. The VELO performance parameters that drive the experiment's physics sensitivity are also given. The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 micron for translations in the plane transverse to the beam. A primary vertex resolution of 13 microns in the transverse plane and 71 microns along the beam axis is achieved for vertices with 25 tracks. An impact parameter resolution of less than 35 microns is achieved for particles with transverse momentum greater than 1 GeV/c. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1405.7808v2-abstract-full').style.display = 'none'; document.getElementById('1405.7808v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 September, 2014; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 May, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">61 pages, 33 figures Minor typographical changes made during journal review are implemented in this version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-LHCb-DP-2014-001 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2014 JINST 9 P09007 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1405.2364">arXiv:1405.2364</a> <span> [<a href="https://arxiv.org/pdf/1405.2364">pdf</a>, <a href="https://arxiv.org/format/1405.2364">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.4889780">10.1063/1.4889780 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nonstatistical dynamics on the caldera </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Kramer%2C+Z+C">Zeb C. Kramer</a>, <a href="/search/physics?searchtype=author&query=Carpenter%2C+B+K">Barry K. Carpenter</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1405.2364v1-abstract-short" style="display: inline;"> We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the `dynamical matching' phenomenon originally proposed by Carpenter, where the momentum direct… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1405.2364v1-abstract-full').style.display = 'inline'; document.getElementById('1405.2364v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1405.2364v1-abstract-full" style="display: none;"> We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the `dynamical matching' phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a `stretched' version of the caldera model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the caldera potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the `dynamical matching' phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1405.2364v1-abstract-full').style.display = 'none'; document.getElementById('1405.2364v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 May, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">54 pages, 17 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1403.6520">arXiv:1403.6520</a> <span> [<a href="https://arxiv.org/pdf/1403.6520">pdf</a>, <a href="https://arxiv.org/format/1403.6520">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> </div> <p class="title is-5 mathjax"> Roaming dynamics in Ketene isomerization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Maugui%C3%A8re%2C+F+A+L">Fr茅d茅ric A. L. Maugui猫re</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Farantos%2C+S+C">Stavros C. Farantos</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1403.6520v1-abstract-short" style="display: inline;"> A reduced two dimensional model is used to study Ketene isomerization reaction. In light of recent results by Ulusoy \textit{et al.} [J.\ Phys.\ Chem.\ A {\bf 117}, 7553 (2013)], the present work focuses on the generalization of the roaming mechanism to the Ketene isomerization reaction by applying our phase space approach previously used to elucidate the roaming phenomenon in ion-molecule reactio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.6520v1-abstract-full').style.display = 'inline'; document.getElementById('1403.6520v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1403.6520v1-abstract-full" style="display: none;"> A reduced two dimensional model is used to study Ketene isomerization reaction. In light of recent results by Ulusoy \textit{et al.} [J.\ Phys.\ Chem.\ A {\bf 117}, 7553 (2013)], the present work focuses on the generalization of the roaming mechanism to the Ketene isomerization reaction by applying our phase space approach previously used to elucidate the roaming phenomenon in ion-molecule reactions. Roaming is again found be associated with the trapping of trajectories in a phase space region between two dividing surfaces; trajectories are classified as reactive or nonreactive, and are further naturally classified as direct or non-direct (roaming). The latter long-lived trajectories are trapped in the region of non-linear mechanical resonances, which in turn define alternative reaction pathways in phase space. It is demonstrated that resonances associated with periodic orbits provide a dynamical explanation of the quantum mechanical resonances found in the isomerization rate constant calculations by Gezelter and Miller [J.\ Chem.\ Phys.\ {\bf 103}, 7868-7876 (1995)]. Evidence of the trapping of trajectories by `sticky' resonant periodic orbits is provided by plotting Poincar茅 surfaces of section, and a gap time analysis is carried out in order to investigate the statistical assumption inherent in transition state theory for Ketene isomerization. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.6520v1-abstract-full').style.display = 'none'; document.getElementById('1403.6520v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 March, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1402.0012">arXiv:1402.0012</a> <span> [<a href="https://arxiv.org/pdf/1402.0012">pdf</a>, <a href="https://arxiv.org/format/1402.0012">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.4870060">10.1063/1.4870060 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Roaming dynamics in ion-molecule reactions: phase space reaction pathways and geometrical interpretation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Maugui%C3%A8re%2C+F+A+L">F. A. L. Maugui猫re</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">G. S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Farantos%2C+S+C">S. C. Farantos</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">S. Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1402.0012v1-abstract-short" style="display: inline;"> A model Hamiltonian for the reaction CH$_4^+ \rightarrow$ CH$_3^+$ + H, parametrized to exhibit either early or late inner transition states, is employed to investigate the dynamical characteristics of the roaming mechanism. Tight/loose transition states and conventional/roaming reaction pathways are identified in terms of time-invariant objects in phase space. These are dividing surfaces associat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.0012v1-abstract-full').style.display = 'inline'; document.getElementById('1402.0012v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1402.0012v1-abstract-full" style="display: none;"> A model Hamiltonian for the reaction CH$_4^+ \rightarrow$ CH$_3^+$ + H, parametrized to exhibit either early or late inner transition states, is employed to investigate the dynamical characteristics of the roaming mechanism. Tight/loose transition states and conventional/roaming reaction pathways are identified in terms of time-invariant objects in phase space. These are dividing surfaces associated with normally hyperbolic invariant manifolds (NHIMs). For systems with two degrees of freedom NHIMS are unstable periodic orbits which, in conjunction with their stable and unstable manifolds, unambiguously define the (locally) non-recrossing dividing surfaces assumed in statistical theories of reaction rates. By constructing periodic orbit continuation/bifurcation diagrams for two values of the potential function parameter corresponding to late and early transition states, respectively, and using the total energy as another parameter, we dynamically assign different regions of phase space to reactants and products as well as to conventional and roaming reaction pathways. The classical dynamics of the system are investigated by uniformly sampling trajectory initial conditions on the dividing surfaces. Trajectories are classified into four different categories: direct reactive and non reactive trajectories,which lead to the formation of molecular and radical products respectively, and roaming reactive and non reactive orbiting trajectories, which represent alternative pathways to form molecular and radical products. By analysing gap time distributions at several energies we demonstrate that the phase space structure of the roaming region, which is strongly influenced by non-linear resonances between the two degrees of freedom, results in nonexponential (nonstatistical) decay. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.0012v1-abstract-full').style.display = 'none'; document.getElementById('1402.0012v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 January, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">44 pages, 14 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1309.6763">arXiv:1309.6763</a> <span> [<a href="https://arxiv.org/pdf/1309.6763">pdf</a>, <a href="https://arxiv.org/ps/1309.6763">ps</a>, <a href="https://arxiv.org/format/1309.6763">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.4825155">10.1063/1.4825155 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nonstatistical dynamics on potentials exhibiting reaction path bifurcations and valley-ridge inflection points </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Carpenter%2C+B+K">Barry K. Carpenter</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1309.6763v2-abstract-short" style="display: inline;"> We study reaction dynamics on a model potential energy surface exhibiting post-transition state bifurcation in the vicinity of a valley ridge inflection point. We compute fractional yields of products reached after the VRI region is traversed, both with and without dissipation. It is found that apparently minor variations in the potential lead to significant changes in the reaction dynamics. Moreo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.6763v2-abstract-full').style.display = 'inline'; document.getElementById('1309.6763v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1309.6763v2-abstract-full" style="display: none;"> We study reaction dynamics on a model potential energy surface exhibiting post-transition state bifurcation in the vicinity of a valley ridge inflection point. We compute fractional yields of products reached after the VRI region is traversed, both with and without dissipation. It is found that apparently minor variations in the potential lead to significant changes in the reaction dynamics. Moreover, when dissipative effects are incorporated, the product ratio depends in a complicated and highly non-monotonic fashion on the dissipation parameter. Dynamics in the vicinity of the VRI point itself play essentially no role in determining the product ratio, except in the highly dissipative regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.6763v2-abstract-full').style.display = 'none'; document.getElementById('1309.6763v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 September, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 September, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">33 pages, 10 figures, corrected the author name in reference [6]</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1309.6432">arXiv:1309.6432</a> <span> [<a href="https://arxiv.org/pdf/1309.6432">pdf</a>, <a href="https://arxiv.org/format/1309.6432">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.cplett.2013.12.051">10.1016/j.cplett.2013.12.051 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiple Transition States and Roaming in Ion-Molecule Reactions: a Phase Space Perspective </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Mauguiere%2C+F+A+L">Frederic A. L. Mauguiere</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Farantos%2C+S+C">Stavros C. Farantos</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1309.6432v1-abstract-short" style="display: inline;"> We provide a dynamical interpretation of the recently identified `roaming' mechanism for molecular dissociation reactions in terms of geometrical structures in phase space. These are NHIMs (Normally Hyperbolic Invariant Manifolds) and their stable/unstable manifolds that define transition states for ion-molecule association or dissociation reactions. The associated dividing surfaces rigorously def… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.6432v1-abstract-full').style.display = 'inline'; document.getElementById('1309.6432v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1309.6432v1-abstract-full" style="display: none;"> We provide a dynamical interpretation of the recently identified `roaming' mechanism for molecular dissociation reactions in terms of geometrical structures in phase space. These are NHIMs (Normally Hyperbolic Invariant Manifolds) and their stable/unstable manifolds that define transition states for ion-molecule association or dissociation reactions. The associated dividing surfaces rigorously define a roaming region of phase space, in which both reactive and nonreactive trajectories can be trapped for arbitrarily long times. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.6432v1-abstract-full').style.display = 'none'; document.getElementById('1309.6432v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 September, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1304.5175">arXiv:1304.5175</a> <span> [<a href="https://arxiv.org/pdf/1304.5175">pdf</a>, <a href="https://arxiv.org/format/1304.5175">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2013.04.060">10.1016/j.nima.2013.04.060 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Timepix Telescope for High Performance Particle Tracking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K">Kazuyoshi Akiba</a>, <a href="/search/physics?searchtype=author&query=Ronning%2C+P+A">Per Arne Ronning</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">Martin van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=van+Beveren%2C+V">Vincent van Beveren</a>, <a href="/search/physics?searchtype=author&query=Borghi%2C+S">Silvia Borghi</a>, <a href="/search/physics?searchtype=author&query=Boterenbrood%2C+H">Henk Boterenbrood</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">Jan Buytaert</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Suarez%2C+A+D">Alvaro Dosil Suarez</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">Raphael Dumps</a>, <a href="/search/physics?searchtype=author&query=Eklund%2C+L">Lars Eklund</a>, <a href="/search/physics?searchtype=author&query=Esperante%2C+D">Daniel Esperante</a>, <a href="/search/physics?searchtype=author&query=Gallas%2C+A">Abraham Gallas</a>, <a href="/search/physics?searchtype=author&query=Gordon%2C+H">Hamish Gordon</a>, <a href="/search/physics?searchtype=author&query=van+der+Heijden%2C+B">Bas van der Heijden</a>, <a href="/search/physics?searchtype=author&query=Hombach%2C+C">Christoph Hombach</a>, <a href="/search/physics?searchtype=author&query=Hynds%2C+D">Daniel Hynds</a>, <a href="/search/physics?searchtype=author&query=John%2C+M">Malcolm John</a>, <a href="/search/physics?searchtype=author&query=Leflat%2C+A">Alexander Leflat</a>, <a href="/search/physics?searchtype=author&query=Li%2C+Y+M">Yi Ming Li</a>, <a href="/search/physics?searchtype=author&query=Longstaff%2C+I">Ian Longstaff</a>, <a href="/search/physics?searchtype=author&query=Morton%2C+A">Alexander Morton</a>, <a href="/search/physics?searchtype=author&query=Nakatsuka%2C+N">Noritsugu Nakatsuka</a>, <a href="/search/physics?searchtype=author&query=Nomerotski%2C+A">Andre Nomerotski</a>, <a href="/search/physics?searchtype=author&query=Parkes%2C+C">Chris Parkes</a> , et al. (10 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1304.5175v1-abstract-short" style="display: inline;"> The Timepix particle tracking telescope has been developed as part of the LHCb VELO Upgrade project, supported by the Medipix Collaboration and the AIDA framework. It is a primary piece of infrastructure for the VELO Upgrade project and is being used for the development of new sensors and front end technologies for several upcoming LHC trackers and vertexing systems. The telescope is designed arou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.5175v1-abstract-full').style.display = 'inline'; document.getElementById('1304.5175v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1304.5175v1-abstract-full" style="display: none;"> The Timepix particle tracking telescope has been developed as part of the LHCb VELO Upgrade project, supported by the Medipix Collaboration and the AIDA framework. It is a primary piece of infrastructure for the VELO Upgrade project and is being used for the development of new sensors and front end technologies for several upcoming LHC trackers and vertexing systems. The telescope is designed around the dual capability of the Timepix ASICs to provide information about either the deposited charge or the timing information from tracks traversing the 14 x 14mm matrix of 55 x 55 um pixels. The rate of reconstructed tracks available is optimised by taking advantage of the shutter driven readout architecture of the Timepix chip, operated with existing readout systems. Results of tests conducted in the SPS North Area beam facility at CERN show that the telescope typically provides reconstructed track rates during the beam spills of between 3.5 and 7.5 kHz, depending on beam conditions. The tracks are time stamped with 1 ns resolution with an efficiency of above 98% and provide a pointing resolution at the centre of the telescope of 1.6 um . By dropping the time stamping requirement the rate can be increased to 15 kHz, at the expense of a small increase in background. The telescope infrastructure provides CO2 cooling and a flexible mechanical interface to the device under test, and has been used for a wide range of measurements during the 2011-2012 data taking campaigns. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.5175v1-abstract-full').style.display = 'none'; document.getElementById('1304.5175v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 April, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1304.3947">arXiv:1304.3947</a> <span> [<a href="https://arxiv.org/pdf/1304.3947">pdf</a>, <a href="https://arxiv.org/format/1304.3947">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1142/S0218127413300437">10.1142/S0218127413300437 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bifurcations of Normally Hyperbolic Invariant Manifolds and Consequences for Reaction Dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Mauguiere%2C+F+A+L">F. A. L. Mauguiere</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">G. S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">S. Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1304.3947v1-abstract-short" style="display: inline;"> In this paper we study the breakdown of normal hyperbolicity and its consequences for reaction dynamics; in particular, the dividing surface, the flux through the dividing surface (DS), and the gap time distribution. Our approach is to study these questions using simple, two degree-of-freedom Hamiltonian models where calculations for the different geometrical and dynamical quantities can be carrie… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.3947v1-abstract-full').style.display = 'inline'; document.getElementById('1304.3947v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1304.3947v1-abstract-full" style="display: none;"> In this paper we study the breakdown of normal hyperbolicity and its consequences for reaction dynamics; in particular, the dividing surface, the flux through the dividing surface (DS), and the gap time distribution. Our approach is to study these questions using simple, two degree-of-freedom Hamiltonian models where calculations for the different geometrical and dynamical quantities can be carried out exactly. For our examples, we show that resonances within the normally hyperbolic invariant manifold may, or may not, lead to a `loss of normal hyperbolicity'. Moreover, we show that the onset of such resonances results in a change in topology of the dividing surface, but does not affect our ability to define a DS. The flux through the DS varies continuously with energy, even as the energy is varied in such a way that normal hyperbolicity is lost. For our examples the gap time distributions exhibit singularities at energies corresponding to the existence of homoclinic orbits in the DS, but these singularities are not associated with loss of normal hyperbolicity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.3947v1-abstract-full').style.display = 'none'; document.getElementById('1304.3947v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 April, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">46 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1302.5259">arXiv:1302.5259</a> <span> [<a href="https://arxiv.org/pdf/1302.5259">pdf</a>, <a href="https://arxiv.org/format/1302.5259">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/8/08/P08002">10.1088/1748-0221/8/08/P08002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Radiation damage in the LHCb Vertex Locator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Affolder%2C+A">A. Affolder</a>, <a href="/search/physics?searchtype=author&query=Akiba%2C+K">K. Akiba</a>, <a href="/search/physics?searchtype=author&query=Alexander%2C+M">M. Alexander</a>, <a href="/search/physics?searchtype=author&query=Ali%2C+S">S. Ali</a>, <a href="/search/physics?searchtype=author&query=Artuso%2C+M">M. Artuso</a>, <a href="/search/physics?searchtype=author&query=Benton%2C+J">J. Benton</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">M. van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Bj%C3%B8rnstad%2C+P+M">P. M. Bj酶rnstad</a>, <a href="/search/physics?searchtype=author&query=Bogdanova%2C+G">G. Bogdanova</a>, <a href="/search/physics?searchtype=author&query=Borghi%2C+S">S. Borghi</a>, <a href="/search/physics?searchtype=author&query=Bowcock%2C+T+J+V">T. J. V. Bowcock</a>, <a href="/search/physics?searchtype=author&query=Brown%2C+H">H. Brown</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">J. Buytaert</a>, <a href="/search/physics?searchtype=author&query=Casse%2C+G">G. Casse</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=De+Capua%2C+S">S. De Capua</a>, <a href="/search/physics?searchtype=author&query=Dossett%2C+D">D. Dossett</a>, <a href="/search/physics?searchtype=author&query=Eklund%2C+L">L. Eklund</a>, <a href="/search/physics?searchtype=author&query=Farinelli%2C+C">C. Farinelli</a>, <a href="/search/physics?searchtype=author&query=Garofoli%2C+J">J. Garofoli</a>, <a href="/search/physics?searchtype=author&query=Gersabeck%2C+M">M. Gersabeck</a>, <a href="/search/physics?searchtype=author&query=Gershon%2C+T">T. Gershon</a>, <a href="/search/physics?searchtype=author&query=Gordon%2C+H">H. Gordon</a>, <a href="/search/physics?searchtype=author&query=Harrison%2C+J">J. Harrison</a>, <a href="/search/physics?searchtype=author&query=Heijne%2C+V">V. Heijne</a> , et al. (26 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1302.5259v1-abstract-short" style="display: inline;"> The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately $\rm{45 \times 10^{12}\,1\,MeV}$ neutron equivalent ($\rm{1\,MeV\,n_{eq}}$). At the op… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.5259v1-abstract-full').style.display = 'inline'; document.getElementById('1302.5259v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1302.5259v1-abstract-full" style="display: none;"> The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately $\rm{45 \times 10^{12}\,1\,MeV}$ neutron equivalent ($\rm{1\,MeV\,n_{eq}}$). At the operational sensor temperature of approximately $-7\,^{\circ}\rm{C}$, the average rate of sensor current increase is $18\,\upmu\rm{A}$ per $\rm{fb^{-1}}$, in excellent agreement with predictions. The silicon effective bandgap has been determined using current versus temperature scan data after irradiation, with an average value of $E_{g}=1.16\pm0.03\pm0.04\,\rm{eV}$ obtained. The first observation of n-on-n sensor type inversion at the LHC has been made, occurring at a fluence of around $15 \times 10 ^{12}$ of $1\,\rm{MeV\,n_{eq}}$. The only n-on-p sensors in use at the LHC have also been studied. With an initial fluence of approximately $\rm{3 \times 10^{12}\,1\,MeV\,n_{eq}}$, a decrease in the Effective Depletion Voltage (EDV) of around 25\,V is observed, attributed to oxygen induced removal of boron interstitial sites. Following this initial decrease, the EDV increases at a comparable rate to the type inverted n-on-n type sensors, with rates of $(1.43\pm 0.16) \times 10 ^{-12}\,\rm{V} / \, 1 \, \rm{MeV\,n_{eq}}$ and $(1.35\pm 0.25) \times 10 ^{-12}\,\rm{V} / \, 1 \, \rm{MeV\,n_{eq}}$ measured for n-on-p and n-on-n type sensors, respectively. A reduction in the charge collection efficiency due to an unexpected effect involving the second metal layer readout lines is observed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.5259v1-abstract-full').style.display = 'none'; document.getElementById('1302.5259v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 February, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-LHCb-DP-2012-005 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1212.2663">arXiv:1212.2663</a> <span> [<a href="https://arxiv.org/pdf/1212.2663">pdf</a>, <a href="https://arxiv.org/format/1212.2663">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> </div> <p class="title is-5 mathjax"> Single versus double bond breakage in a Morse chain under tension: higher index saddles and bond healing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Mauguiere%2C+F+A+L">F. A. L. Mauguiere</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">G. S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">S. Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1212.2663v1-abstract-short" style="display: inline;"> We investigate the fragmentation dynamics of an atomic chain under tensile stress. We have classified the location, stability type (indices) and energy of all equilibria for the general $n$-particle chain, and have highlighted the importance of saddle points with index $> 1$. We show that for an $n=2$-particle chain under tensile stress the index 2 saddle plays a central role in organizing the d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1212.2663v1-abstract-full').style.display = 'inline'; document.getElementById('1212.2663v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1212.2663v1-abstract-full" style="display: none;"> We investigate the fragmentation dynamics of an atomic chain under tensile stress. We have classified the location, stability type (indices) and energy of all equilibria for the general $n$-particle chain, and have highlighted the importance of saddle points with index $> 1$. We show that for an $n=2$-particle chain under tensile stress the index 2 saddle plays a central role in organizing the dynamics. We apply normal form theory to analyze phase space structure and dynamics in a neighborhood of the index 2 saddle. We define a phase dividing surface (DS) that enables us to classify trajectories passing through a neighborhood of the saddle point using the values of the integrals associated with the normal form. We also generalize our definition of the dividing surface and define an \emph{extended dividing surface} (EDS), which is used to sample and classify all trajectories that pass through a phase space neighborhood of the index 2 saddle at total energies less than that of the saddle. Classical trajectory simulations are used to study single versus double bond breakage for the $n=2$ chain under tension. Initial conditions for trajectories are obtained by sampling the EDS at constant energy. We sample trajectories at fixed energies both above and below the energy of the saddle. The fate of trajectories (single versus double bond breakage) is explored as a function of the location of the initial condition on the EDS, and a connection made to the work of Chesnavich on collision-induced dissociation. A significant finding is that we can readily identify trajectories that exhibit bond \emph{healing}. Such trajectories pass outside the nominal (index 1) transition state for single bond dissociation, but return to the potential well region, possibly several times, before ultimately dissociating. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1212.2663v1-abstract-full').style.display = 'none'; document.getElementById('1212.2663v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 December, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">54 pages, 19 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1211.1176">arXiv:1211.1176</a> <span> [<a href="https://arxiv.org/pdf/1211.1176">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/8/04/P04004">10.1088/1748-0221/8/04/P04004 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evaporative CO2 cooling using microchannels etched in silicon for the future LHCb vertex detector </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Nomerotski%2C+A">A. Nomerotski</a>, <a href="/search/physics?searchtype=author&query=Buytart%2C+J">J. Buytart</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">R. Dumps</a>, <a href="/search/physics?searchtype=author&query=Greening%2C+E">E. Greening</a>, <a href="/search/physics?searchtype=author&query=John%2C+M">M. John</a>, <a href="/search/physics?searchtype=author&query=Mapelli%2C+A">A. Mapelli</a>, <a href="/search/physics?searchtype=author&query=Leflat%2C+A">A. Leflat</a>, <a href="/search/physics?searchtype=author&query=Li%2C+Y">Y. Li</a>, <a href="/search/physics?searchtype=author&query=Romagnoli%2C+G">G. Romagnoli</a>, <a href="/search/physics?searchtype=author&query=Verlaat%2C+B">B. Verlaat</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1211.1176v4-abstract-short" style="display: inline;"> The extreme radiation dose received by vertex detectors at the Large Hadron Collider dictates stringent requirements on their cooling systems. To be robust against radiation damage, sensors should be maintained below -20 degree C and at the same time, the considerable heat load generated in the readout chips and the sensors must be removed. Evaporative CO2 cooling using microchannels etched in a s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.1176v4-abstract-full').style.display = 'inline'; document.getElementById('1211.1176v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1211.1176v4-abstract-full" style="display: none;"> The extreme radiation dose received by vertex detectors at the Large Hadron Collider dictates stringent requirements on their cooling systems. To be robust against radiation damage, sensors should be maintained below -20 degree C and at the same time, the considerable heat load generated in the readout chips and the sensors must be removed. Evaporative CO2 cooling using microchannels etched in a silicon plane in thermal contact with the readout chips is an attractive option. In this paper, we present the first results of microchannel prototypes with circulating, two-phase CO2 and compare them to simulations. We also discuss a practical design of upgraded VELO detector for the LHCb experiment employing this approach. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.1176v4-abstract-full').style.display = 'none'; document.getElementById('1211.1176v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 February, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 November, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A. Nomerotski et al (2013) JINST 8 P04004 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1208.0251">arXiv:1208.0251</a> <span> [<a href="https://arxiv.org/pdf/1208.0251">pdf</a>, <a href="https://arxiv.org/format/1208.0251">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2013.03.040">10.1016/j.nima.2013.03.040 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> R&D Paths of Pixel Detectors for Vertex Tracking and Radiation Imaging </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Battaglia%2C+M">M. Battaglia</a>, <a href="/search/physics?searchtype=author&query=Da+Via%2C+C">C. Da Via</a>, <a href="/search/physics?searchtype=author&query=Bortoletto%2C+D">D. Bortoletto</a>, <a href="/search/physics?searchtype=author&query=Brenner%2C+R">R. Brenner</a>, <a href="/search/physics?searchtype=author&query=Campbell%2C+M">M. Campbell</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">P. Collins</a>, <a href="/search/physics?searchtype=author&query=Betta%2C+G+F+D">G. F. Dalla Betta</a>, <a href="/search/physics?searchtype=author&query=Denes%2C+P">P. Denes</a>, <a href="/search/physics?searchtype=author&query=Graafsma%2C+H">H. Graafsma</a>, <a href="/search/physics?searchtype=author&query=Gregor%2C+I+M">I. M. Gregor</a>, <a href="/search/physics?searchtype=author&query=Kluge%2C+A">A. Kluge</a>, <a href="/search/physics?searchtype=author&query=Manzari%2C+V">V. Manzari</a>, <a href="/search/physics?searchtype=author&query=Parkes%2C+C">C. Parkes</a>, <a href="/search/physics?searchtype=author&query=Re%2C+V">V. Re</a>, <a href="/search/physics?searchtype=author&query=Riedler%2C+P">P. Riedler</a>, <a href="/search/physics?searchtype=author&query=Rizzo%2C+G">G. Rizzo</a>, <a href="/search/physics?searchtype=author&query=Snoeys%2C+W">W. Snoeys</a>, <a href="/search/physics?searchtype=author&query=Winter%2C+M">M. Winter</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1208.0251v1-abstract-short" style="display: inline;"> This report reviews current trends in the R&D of semiconductor pixellated sensors for vertex tracking and radiation imaging. It identifies requirements of future HEP experiments at colliders, needed technological breakthroughs and highlights the relation to radiation detection and imaging applications in other fields of science. </span> <span class="abstract-full has-text-grey-dark mathjax" id="1208.0251v1-abstract-full" style="display: none;"> This report reviews current trends in the R&D of semiconductor pixellated sensors for vertex tracking and radiation imaging. It identifies requirements of future HEP experiments at colliders, needed technological breakthroughs and highlights the relation to radiation detection and imaging applications in other fields of science. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1208.0251v1-abstract-full').style.display = 'none'; document.getElementById('1208.0251v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 August, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 2 figures, submitted to the European Strategy Preparatory Group</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1110.2866">arXiv:1110.2866</a> <span> [<a href="https://arxiv.org/pdf/1110.2866">pdf</a>, <a href="https://arxiv.org/format/1110.2866">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/7/01/P01010">10.1088/1748-0221/7/01/P01010 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Absolute luminosity measurements with the LHCb detector at the LHC </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=The+LHCb+Collaboration"> The LHCb Collaboration</a>, <a href="/search/physics?searchtype=author&query=Aaij%2C+R">R. Aaij</a>, <a href="/search/physics?searchtype=author&query=Adeva%2C+B">B. Adeva</a>, <a href="/search/physics?searchtype=author&query=Adinolfi%2C+M">M. Adinolfi</a>, <a href="/search/physics?searchtype=author&query=Adrover%2C+C">C. Adrover</a>, <a href="/search/physics?searchtype=author&query=Affolder%2C+A">A. Affolder</a>, <a href="/search/physics?searchtype=author&query=Ajaltouni%2C+Z">Z. Ajaltouni</a>, <a href="/search/physics?searchtype=author&query=Albrecht%2C+J">J. Albrecht</a>, <a href="/search/physics?searchtype=author&query=Alessio%2C+F">F. Alessio</a>, <a href="/search/physics?searchtype=author&query=Alexander%2C+M">M. Alexander</a>, <a href="/search/physics?searchtype=author&query=Alkhazov%2C+G">G. Alkhazov</a>, <a href="/search/physics?searchtype=author&query=Cartelle%2C+P+A">P. Alvarez Cartelle</a>, <a href="/search/physics?searchtype=author&query=Alves%2C+A+A">A. A. Alves Jr</a>, <a href="/search/physics?searchtype=author&query=Amato%2C+S">S. Amato</a>, <a href="/search/physics?searchtype=author&query=Amhis%2C+Y">Y. Amhis</a>, <a href="/search/physics?searchtype=author&query=Anderson%2C+J">J. Anderson</a>, <a href="/search/physics?searchtype=author&query=Appleby%2C+R+B">R. B. Appleby</a>, <a href="/search/physics?searchtype=author&query=Gutierrez%2C+O+A">O. Aquines Gutierrez</a>, <a href="/search/physics?searchtype=author&query=Archilli%2C+F">F. Archilli</a>, <a href="/search/physics?searchtype=author&query=Arrabito%2C+L">L. Arrabito</a>, <a href="/search/physics?searchtype=author&query=Artamonov%2C+A">A. Artamonov</a>, <a href="/search/physics?searchtype=author&query=Artuso%2C+M">M. Artuso</a>, <a href="/search/physics?searchtype=author&query=Aslanides%2C+E">E. Aslanides</a>, <a href="/search/physics?searchtype=author&query=Auriemma%2C+G">G. Auriemma</a>, <a href="/search/physics?searchtype=author&query=Bachmann%2C+S">S. Bachmann</a> , et al. (549 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1110.2866v2-abstract-short" style="display: inline;"> Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-prot… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1110.2866v2-abstract-full').style.display = 'inline'; document.getElementById('1110.2866v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1110.2866v2-abstract-full" style="display: none;"> Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1110.2866v2-abstract-full').style.display = 'none'; document.getElementById('1110.2866v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 January, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 October, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">48 pages, 19 figures. Results unchanged, improved clarity of Table 6, 9 and 10 and corresponding explanation in the text</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-PAPER-2011-015; CERN-PH-EP-2011-157 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2012 JINST 7 P01010 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1104.1343">arXiv:1104.1343</a> <span> [<a href="https://arxiv.org/pdf/1104.1343">pdf</a>, <a href="https://arxiv.org/format/1104.1343">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.3602465">10.1063/1.3602465 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Index k saddles and dividing surfaces in phase space, with applications to isomerization dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1104.1343v1-abstract-short" style="display: inline;"> In this paper we continue our studies of the phase space geometry and dynamics associated with index k saddles (k > 1) of the potential energy surface. Using normal form theory, we give an explicit formula for a "dividing surface" in phase space, i.e. a co-dimension one surface (within the energy shell) through which all trajectories that "cross" the region of the index k saddle must pass. With a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1104.1343v1-abstract-full').style.display = 'inline'; document.getElementById('1104.1343v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1104.1343v1-abstract-full" style="display: none;"> In this paper we continue our studies of the phase space geometry and dynamics associated with index k saddles (k > 1) of the potential energy surface. Using normal form theory, we give an explicit formula for a "dividing surface" in phase space, i.e. a co-dimension one surface (within the energy shell) through which all trajectories that "cross" the region of the index k saddle must pass. With a generic non-resonance assumption, the normal form provides k (approximate) integrals that describe the saddle dynamics in a neighborhood of the index k saddle. These integrals provide a symbolic description of all trajectories that pass through a neighborhood of the saddle. We give a parametrization of the dividing surface which is used as the basis for a numerical method to sample the dividing surface. Our techniques are applied to isomerization dynamics on a potential energy surface having 4 minima; two symmetry related pairs of minima are connected by low energy index one saddles, with the pairs themselves connected via higher energy index one saddles and an index two saddle at the origin. We compute and sample the dividing surface and show that our approach enables us to distinguish between concerted crossing ("hilltop crossing") isomerizing trajectories and those trajectories that are not concerted crossing (potentially sequentially isomerizing trajectories). We then consider the effect of additional "bath modes" on the dynamics, which is a four degree-of-freedom system. For this system we show that the normal form and dividing surface can be realized and sampled and that, using the approximate integrals of motion and our symbolic description of trajectories, we are able to choose initial conditions corresponding to concerted crossing isomerizing trajectories and (potentially) sequentially isomerizing trajectories. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1104.1343v1-abstract-full').style.display = 'none'; document.getElementById('1104.1343v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 April, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">49 pages, 12 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1103.2739">arXiv:1103.2739</a> <span> [<a href="https://arxiv.org/pdf/1103.2739">pdf</a>, <a href="https://arxiv.org/ps/1103.2739">ps</a>, <a href="https://arxiv.org/format/1103.2739">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2011.09.021">10.1016/j.nima.2011.09.021 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Charged Particle Tracking with the Timepix ASIC </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Akiba%2C+K">Kazuyoshi Akiba</a>, <a href="/search/physics?searchtype=author&query=Artuso%2C+M">Marina Artuso</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+R">Ryan Badman</a>, <a href="/search/physics?searchtype=author&query=Borgia%2C+A">Alessandra Borgia</a>, <a href="/search/physics?searchtype=author&query=Bates%2C+R">Richard Bates</a>, <a href="/search/physics?searchtype=author&query=Bayer%2C+F">Florian Bayer</a>, <a href="/search/physics?searchtype=author&query=van+Beuzekom%2C+M">Martin van Beuzekom</a>, <a href="/search/physics?searchtype=author&query=Buytaert%2C+J">Jan Buytaert</a>, <a href="/search/physics?searchtype=author&query=Cabruja%2C+E">Enric Cabruja</a>, <a href="/search/physics?searchtype=author&query=Campbell%2C+M">Michael Campbell</a>, <a href="/search/physics?searchtype=author&query=Collins%2C+P">Paula Collins</a>, <a href="/search/physics?searchtype=author&query=Crossley%2C+M">Michael Crossley</a>, <a href="/search/physics?searchtype=author&query=Dumps%2C+R">Raphael Dumps</a>, <a href="/search/physics?searchtype=author&query=Eklund%2C+L">Lars Eklund</a>, <a href="/search/physics?searchtype=author&query=Esperante%2C+D">Daniel Esperante</a>, <a href="/search/physics?searchtype=author&query=Fleta%2C+C">Celeste Fleta</a>, <a href="/search/physics?searchtype=author&query=Gallas%2C+A">Abraham Gallas</a>, <a href="/search/physics?searchtype=author&query=Gandelman%2C+M">Miriam Gandelman</a>, <a href="/search/physics?searchtype=author&query=Garofoli%2C+J">Justin Garofoli</a>, <a href="/search/physics?searchtype=author&query=Gersabeck%2C+M">Marco Gersabeck</a>, <a href="/search/physics?searchtype=author&query=Gligorov%2C+V+V">Vladimir V. Gligorov</a>, <a href="/search/physics?searchtype=author&query=Gordon%2C+H">Hamish Gordon</a>, <a href="/search/physics?searchtype=author&query=Heijne%2C+E+H+M">Erik H. M. Heijne</a>, <a href="/search/physics?searchtype=author&query=Heijne%2C+V">Veerle Heijne</a>, <a href="/search/physics?searchtype=author&query=Hynds%2C+D">Daniel Hynds</a> , et al. (17 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1103.2739v3-abstract-short" style="display: inline;"> A prototype particle tracking telescope has been constructed using Timepix and Medipix ASIC hybrid pixel assemblies as the six sensing planes. Each telescope plane consisted of one 1.4 cm2 assembly, providing a 256x256 array of 55 micron square pixels. The telescope achieved a pointing resolution of 2.3 micron at the position of the device under test. During a beam test in 2009 the telescope was u… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1103.2739v3-abstract-full').style.display = 'inline'; document.getElementById('1103.2739v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1103.2739v3-abstract-full" style="display: none;"> A prototype particle tracking telescope has been constructed using Timepix and Medipix ASIC hybrid pixel assemblies as the six sensing planes. Each telescope plane consisted of one 1.4 cm2 assembly, providing a 256x256 array of 55 micron square pixels. The telescope achieved a pointing resolution of 2.3 micron at the position of the device under test. During a beam test in 2009 the telescope was used to evaluate in detail the performance of two Timepix hybrid pixel assemblies; a standard planar 300 micron thick sensor, and 285 micron thick double sided 3D sensor. This paper describes a detailed charge calibration study of the pixel devices, which allows the true charge to be extracted, and reports on measurements of the charge collection characteristics and Landau distributions. The planar sensor achieved a best resolution of 4.0 micron for angled tracks, and resolutions of between 4.4 and 11 micron for perpendicular tracks, depending on the applied bias voltage. The double sided 3D sensor, which has significantly less charge sharing, was found to have an optimal resolution of 9.0 micron for angled tracks, and a resolution of 16.0 micron for perpendicular tracks. Based on these studies it is concluded that the Timepix ASIC shows an excellent performance when used as a device for charged particle tracking. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1103.2739v3-abstract-full').style.display = 'none'; document.getElementById('1103.2739v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 June, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 March, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">51 pages, 39 figures. Submitted to Nucl. Phys. Meth. A. ; Contact authors: P. Collins and V. V. Gligorov</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> LHCb-PUB-2011-010 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1004.4294">arXiv:1004.4294</a> <span> [<a href="https://arxiv.org/pdf/1004.4294">pdf</a>, <a href="https://arxiv.org/format/1004.4294">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.3455712">10.1063/1.3455712 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phase space structure and dynamics for the Hamiltonian isokinetic thermostat </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Collins%2C+P">Peter Collins</a>, <a href="/search/physics?searchtype=author&query=Ezra%2C+G+S">Gregory S. Ezra</a>, <a href="/search/physics?searchtype=author&query=Wiggins%2C+S">Stephen Wiggins</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1004.4294v1-abstract-short" style="display: inline;"> We investigate the phase space structure and dynamics of a Hamiltonian isokinetic thermostat, for which ergodic thermostat trajectories at fixed (zero) energy generate a canonical distribution in configuration space. Model potentials studied consist of a single bistable mode plus transverse harmonic modes. Interpreting the bistable mode as a reaction (isomerization) coordinate, we establish conne… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1004.4294v1-abstract-full').style.display = 'inline'; document.getElementById('1004.4294v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1004.4294v1-abstract-full" style="display: none;"> We investigate the phase space structure and dynamics of a Hamiltonian isokinetic thermostat, for which ergodic thermostat trajectories at fixed (zero) energy generate a canonical distribution in configuration space. Model potentials studied consist of a single bistable mode plus transverse harmonic modes. Interpreting the bistable mode as a reaction (isomerization) coordinate, we establish connections with the theory of unimolecular reaction rates, in particular the formulation of isomerization rates in terms of gap times. The distribution of gap times (or associated lifetimes) for a microcanonical ensemble initiated on the dividing surface is of great dynamical significance; an exponential lifetime distribution is usually taken to be an indicator of `statistical' behavior. Moreover, comparison of the magnitude of the phase space volume swept out by reactive trajectories as they pass through the reactant region with the total phase space volume (classical density of states) for the reactant region provides a necessary condition for ergodic dynamics. We compute gap times, associated lifetime distributions, mean gap times, reactive fluxes, reactive volumes and total reactant phase space volumes for model systems with 3 degrees of freedom, at three different temperatures. At all three temperatures, the necessary condition for ergodicity is approximately satisfied. At high temperatures a non-exponential lifetime distribution is found, while at low temperatures the lifetime is more nearly exponential. The degree of exponentiality of the lifetime distribution is quantified by computing the information entropy deficit with respect to pure exponential decay. The efficacy of the Hamiltonian isokinetic thermostat is examined by computing coordinate distributions averaged over single long trajectories initiated on the dividing surface. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1004.4294v1-abstract-full').style.display = 'none'; document.getElementById('1004.4294v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 April, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">55 pages, 12 figures</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 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