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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/2402.06193">arXiv:2402.06193</a> <span> [<a href="https://arxiv.org/pdf/2402.06193">pdf</a>, <a href="https://arxiv.org/format/2402.06193">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-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/10.3847/1538-4357/ad528f">10.3847/1538-4357/ad528f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental study of Alfv茅n wave reflection from an Alfv茅n-speed gradient relevant to the solar coronal holes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bose%2C+S">Sayak Bose</a>, <a href="/search/physics?searchtype=author&query=TenBarge%2C+J+M">Jason M. TenBarge</a>, <a href="/search/physics?searchtype=author&query=Carter%2C+T">Troy Carter</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Ji%2C+H">Hantao Ji</a>, <a href="/search/physics?searchtype=author&query=Juno%2C+J">James Juno</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</a>, <a href="/search/physics?searchtype=author&query=Tripathi%2C+S">Shreekrishna Tripathi</a>, <a href="/search/physics?searchtype=author&query=Vincena%2C+S">Stephen Vincena</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="2402.06193v1-abstract-short" style="display: inline;"> We report the first experimental detection of a reflected Alfv茅n wave from an Alfv茅n-speed gradient under conditions similar to those in coronal holes. The experiments were conducted in the Large Plasma Device at the University of California, Los Angeles. We present the experimentally measured dependence of the coefficient of reflection versus the wave inhomogeneity parameter, i.e., the ratio of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.06193v1-abstract-full').style.display = 'inline'; document.getElementById('2402.06193v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.06193v1-abstract-full" style="display: none;"> We report the first experimental detection of a reflected Alfv茅n wave from an Alfv茅n-speed gradient under conditions similar to those in coronal holes. The experiments were conducted in the Large Plasma Device at the University of California, Los Angeles. We present the experimentally measured dependence of the coefficient of reflection versus the wave inhomogeneity parameter, i.e., the ratio of the wave length of the incident wave to the length scale of the gradient. Two-fluid simulations using the Gkeyll code qualitatively agree with and support the experimental findings. Our experimental results support models of wave heating that rely on wave reflection at low heights from a smooth Alfv茅n-speed gradient to drive turbulence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.06193v1-abstract-full').style.display = 'none'; document.getElementById('2402.06193v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.03772">arXiv:2303.03772</a> <span> [<a href="https://arxiv.org/pdf/2303.03772">pdf</a>, <a href="https://arxiv.org/format/2303.03772">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Data Analysis, Statistics and Probability">physics.data-an</span> <span class="tag is-small is-grey 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="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> The human factor: results of a small-angle scattering data analysis Round Robin </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Pauw%2C+B+R">Brian R. Pauw</a>, <a href="/search/physics?searchtype=author&query=Smales%2C+G+J">Glen J. Smales</a>, <a href="/search/physics?searchtype=author&query=Anker%2C+A+S">Andy S. Anker</a>, <a href="/search/physics?searchtype=author&query=Balazs%2C+D+M">Daniel M. Balazs</a>, <a href="/search/physics?searchtype=author&query=Beyer%2C+F+L">Frederick L. Beyer</a>, <a href="/search/physics?searchtype=author&query=Bienert%2C+R">Ralf Bienert</a>, <a href="/search/physics?searchtype=author&query=Bouwman%2C+W+G">Wim G. Bouwman</a>, <a href="/search/physics?searchtype=author&query=Bre%C3%9Fler%2C+I">Ingo Bre脽ler</a>, <a href="/search/physics?searchtype=author&query=Breternitz%2C+J">Joachim Breternitz</a>, <a href="/search/physics?searchtype=author&query=Brok%2C+E+S">Erik S Brok</a>, <a href="/search/physics?searchtype=author&query=Bryant%2C+G">Gary Bryant</a>, <a href="/search/physics?searchtype=author&query=Clulow%2C+A+J">Andrew J. Clulow</a>, <a href="/search/physics?searchtype=author&query=Crater%2C+E+R">Erin R. Crater</a>, <a href="/search/physics?searchtype=author&query=De+Geuser%2C+F">Fr茅d茅ric De Geuser</a>, <a href="/search/physics?searchtype=author&query=Del+Giudice%2C+A">Alessandra Del Giudice</a>, <a href="/search/physics?searchtype=author&query=Deumer%2C+J">J茅r么me Deumer</a>, <a href="/search/physics?searchtype=author&query=Disch%2C+S">Sabrina Disch</a>, <a href="/search/physics?searchtype=author&query=Dutt%2C+S">Shankar Dutt</a>, <a href="/search/physics?searchtype=author&query=Frank%2C+K">Kilian Frank</a>, <a href="/search/physics?searchtype=author&query=Fratini%2C+E">Emiliano Fratini</a>, <a href="/search/physics?searchtype=author&query=Gilbert%2C+E+P">Elliot P. Gilbert</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M+B">Marc Benjamin Hahn</a>, <a href="/search/physics?searchtype=author&query=Hallett%2C+J">James Hallett</a>, <a href="/search/physics?searchtype=author&query=Hohenschutz%2C+M">Max Hohenschutz</a>, <a href="/search/physics?searchtype=author&query=Hollamby%2C+M">Martin Hollamby</a> , et al. (24 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="2303.03772v1-abstract-short" style="display: inline;"> A Round Robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions, and two from powders. Most of the 46 participants correctly identified the number of pop… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.03772v1-abstract-full').style.display = 'inline'; document.getElementById('2303.03772v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.03772v1-abstract-full" style="display: none;"> A Round Robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions, and two from powders. Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5% and half of the population width entries within 40%, respectively. Due to the added complexity of the structure factor, much fewer people submitted answers on the powder datasets. For those that did, half of the entries for the means and widths were within 44% and 86% respectively. This Round Robin experiment highlights several causes for the discrepancies, for which solutions are proposed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.03772v1-abstract-full').style.display = 'none'; document.getElementById('2303.03772v1-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 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">23 pages, 10 figures. For the original information sent to RR participants, see https://zenodo.org/record/7506365 . For the anonymized results and Jupyter notebook for analysis, see https://zenodo.org/record/7509710</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.03487">arXiv:2207.03487</a> <span> [<a href="https://arxiv.org/pdf/2207.03487">pdf</a>, <a href="https://arxiv.org/format/2207.03487">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 Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</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/10.1364/JOSAA.471477">10.1364/JOSAA.471477 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Deriving instrumental point spread functions from partially occulted images </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hofmeister%2C+S+J">Stefan Johann Hofmeister</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="2207.03487v2-abstract-short" style="display: inline;"> The point-spread function (PSF) of an imaging system describes the response of the system to a point source. Accurately determining the PSF enables one to correct for the combined effects of focussing and scattering within the imaging system, and thereby enhance the spatial resolution and dynamic contrast of the resulting images. We present a semi-empirical semi-blind methodology to derive a PSF f… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.03487v2-abstract-full').style.display = 'inline'; document.getElementById('2207.03487v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.03487v2-abstract-full" style="display: none;"> The point-spread function (PSF) of an imaging system describes the response of the system to a point source. Accurately determining the PSF enables one to correct for the combined effects of focussing and scattering within the imaging system, and thereby enhance the spatial resolution and dynamic contrast of the resulting images. We present a semi-empirical semi-blind methodology to derive a PSF from partially occulted images. We partition the two-dimensional PSF into multiple segments, set up a multi-linear system of equations, and directly fit the system of equations to determine the PSF weight in each segment. The algorithm is guaranteed to converge towards the correct instrumental PSF for a large class of occultations, does not require a predefined functional form of the PSF, and can be applied to a large variety of partially occulted images, such as within laboratory settings, regular calibrations within a production line or in the field, astronomical images of distant clusters of stars, or partial solar eclipse images. We show that the central weight of the PSF, which gives the percentage of photons that are not scattered by the instrument, is accurate to bettern than 1.2%. The mean absolute percentage error between the reconstructed and true PSF is usually between 0.5% and 5% for the entire PSF, between 0.5% and 5% for the PSF core, and between 0.5% and 3% for the PSF tail. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.03487v2-abstract-full').style.display = 'none'; document.getElementById('2207.03487v2-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.09559">arXiv:2204.09559</a> <span> [<a href="https://arxiv.org/pdf/2204.09559">pdf</a>, <a href="https://arxiv.org/ps/2204.09559">ps</a>, <a href="https://arxiv.org/format/2204.09559">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-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/10.3847/1538-4357/ac7147">10.3847/1538-4357/ac7147 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evidence for Parameteric Decay Instability in the Lower Solar Atmosphere </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Fu%2C+X">Xiangrong Fu</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="2204.09559v1-abstract-short" style="display: inline;"> We find evidence for the first observation of the parametric decay instability (PDI) in the lower solar atmosphere. Specifically, we find that the power spectrum of density fluctuations near the solar transition region resembles the power spectrum of the velocity fluctuations, but with the frequency axis scaled up by about a factor of two. These results are from an analysis of the Si IV lines obse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09559v1-abstract-full').style.display = 'inline'; document.getElementById('2204.09559v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.09559v1-abstract-full" style="display: none;"> We find evidence for the first observation of the parametric decay instability (PDI) in the lower solar atmosphere. Specifically, we find that the power spectrum of density fluctuations near the solar transition region resembles the power spectrum of the velocity fluctuations, but with the frequency axis scaled up by about a factor of two. These results are from an analysis of the Si IV lines observed by the Interface Region Imaging Spectrometer (IRIS) in the transition region of a polar coronal hole. We also find that the density fluctuations have radial velocity of about 75 km/s and that the velocity fluctuations are much faster with an estimated speed of 250 km/s, as is expected for sound waves and Alfv茅n waves, respectively, in the transition region. Theoretical calculations show that this frequency relationship is consistent with those expected from PDI for the plasma conditions of the observed region. These measurements suggest an interaction between sound waves and Alfv茅n waves in the transition region that is evidence for the parametric decay instability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09559v1-abstract-full').style.display = 'none'; document.getElementById('2204.09559v1-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> 20 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">Submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.00268">arXiv:2007.00268</a> <span> [<a href="https://arxiv.org/pdf/2007.00268">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Populations and Evolution">q-bio.PE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atmospheric and Oceanic Physics">physics.ao-ph</span> </div> </div> <p class="title is-5 mathjax"> Reply to Zhang et al.: Linear regression does not encapsulate the effect of non-pharmaceutical interventions on the number of COVID-19 cases </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Pendergrass%2C+A+G">Angeline G. Pendergrass</a>, <a href="/search/physics?searchtype=author&query=Ebi%2C+K+L">Kristie L. Ebi</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M+B">Micah B. Hahn</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="2007.00268v6-abstract-short" style="display: inline;"> Zhang et al. (2020) used linear regression to quantify the effect of lockdowns on the number of cases of COVID-19. We show using differential equations from the susceptible-exposed-infected-recovered (SEIR) model and with an example from another location not previously considered that the Zhang et al. analysis should not be considered sound evidence that mask mandates are sufficient to control or… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.00268v6-abstract-full').style.display = 'inline'; document.getElementById('2007.00268v6-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.00268v6-abstract-full" style="display: none;"> Zhang et al. (2020) used linear regression to quantify the effect of lockdowns on the number of cases of COVID-19. We show using differential equations from the susceptible-exposed-infected-recovered (SEIR) model and with an example from another location not previously considered that the Zhang et al. analysis should not be considered sound evidence that mask mandates are sufficient to control or the primary factor controlling the spread of COVID-19. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.00268v6-abstract-full').style.display = 'none'; document.getElementById('2007.00268v6-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 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 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">Submitted as a letter to Proceedings of the National Academy of Sciences of the United States of America</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1908.08094">arXiv:1908.08094</a> <span> [<a href="https://arxiv.org/pdf/1908.08094">pdf</a>, <a href="https://arxiv.org/ps/1908.08094">ps</a>, <a href="https://arxiv.org/format/1908.08094">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.3847/1538-4357/ab67b4">10.3847/1538-4357/ab67b4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Laboratory Calibrations of Fe XII-XIV Line-Intensity Ratios for Electron Density Diagnostics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Arthanayaka%2C+T+P">Thusitha P. Arthanayaka</a>, <a href="/search/physics?searchtype=author&query=Beiersdorfer%2C+P">Peter Beiersdorfer</a>, <a href="/search/physics?searchtype=author&query=Brown%2C+G+V">Gregory V. Brown</a>, <a href="/search/physics?searchtype=author&query=Gu%2C+M+F">Ming Feng Gu</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Hell%2C+N">Natalie Hell</a>, <a href="/search/physics?searchtype=author&query=Lockard%2C+T+E">Tom E. Lockard</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="1908.08094v1-abstract-short" style="display: inline;"> We have used an electron beam ion trap to measure electron-density-diagnostic line-intensity ratios for extreme ultraviolet lines from F XII, XIII, and XIV at wavelengths of 185-205 255-276 Angstroms. These ratios can be used as density diagnostics for astrophysical spectra and are especially relevant to solar physics. We found that density diagnostics using the Fe XIII 196.53/202.04 and the Fe XI… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.08094v1-abstract-full').style.display = 'inline'; document.getElementById('1908.08094v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1908.08094v1-abstract-full" style="display: none;"> We have used an electron beam ion trap to measure electron-density-diagnostic line-intensity ratios for extreme ultraviolet lines from F XII, XIII, and XIV at wavelengths of 185-205 255-276 Angstroms. These ratios can be used as density diagnostics for astrophysical spectra and are especially relevant to solar physics. We found that density diagnostics using the Fe XIII 196.53/202.04 and the Fe XIV 264.79/274.21 and 270.52A/274.21 line ratios are reliable using the atomic data calculated with the Flexible Atomic Code. On the other hand, we found a large discrepancy between the FAC theory and experiment for the commonly used Fe XII (186.85 + 186.88)/195.12 line ratio. These FAC theory calculations give similar results to the data tabulated in CHIANTI, which are commonly used to analyze solar observations. Our results suggest that the discrepancies seen between solar coronal density measurements using the Fe XII (186.85 + 186.88)/195.12 and Fe XIII 196.54/202.04 line ratios are likely due to issues with the atomic calculations for Fe XII. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.08094v1-abstract-full').style.display = 'none'; document.getElementById('1908.08094v1-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 August, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.08857">arXiv:1905.08857</a> <span> [<a href="https://arxiv.org/pdf/1905.08857">pdf</a>, <a href="https://arxiv.org/format/1905.08857">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Experiment">nucl-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/10.1103/PhysRevAccelBeams.22.102401">10.1103/PhysRevAccelBeams.22.102401 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A fast-switching magnet serving a spallation-driven ultracold neutron source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Ahmed%2C+S">S. Ahmed</a>, <a href="/search/physics?searchtype=author&query=Altiere%2C+E">E. Altiere</a>, <a href="/search/physics?searchtype=author&query=Andalib%2C+T">T. Andalib</a>, <a href="/search/physics?searchtype=author&query=Barnes%2C+M+J">M. J. Barnes</a>, <a href="/search/physics?searchtype=author&query=Bell%2C+B">B. Bell</a>, <a href="/search/physics?searchtype=author&query=Bidinosti%2C+C+P">C. P. Bidinosti</a>, <a href="/search/physics?searchtype=author&query=Bylinsky%2C+Y">Y. Bylinsky</a>, <a href="/search/physics?searchtype=author&query=Chak%2C+J">J. Chak</a>, <a href="/search/physics?searchtype=author&query=Das%2C+M">M. Das</a>, <a href="/search/physics?searchtype=author&query=Davis%2C+C+A">C. A. Davis</a>, <a href="/search/physics?searchtype=author&query=Fischer%2C+F">F. Fischer</a>, <a href="/search/physics?searchtype=author&query=Franke%2C+B">B. Franke</a>, <a href="/search/physics?searchtype=author&query=Gericke%2C+M+T+W">M. T. W. Gericke</a>, <a href="/search/physics?searchtype=author&query=Giampa%2C+P">P. Giampa</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Hansen-Romu%2C+S">S. Hansen-Romu</a>, <a href="/search/physics?searchtype=author&query=Hatanaka%2C+K">K. Hatanaka</a>, <a href="/search/physics?searchtype=author&query=Hayamizu%2C+T">T. Hayamizu</a>, <a href="/search/physics?searchtype=author&query=Jamieson%2C+B">B. Jamieson</a>, <a href="/search/physics?searchtype=author&query=Jones%2C+D">D. Jones</a>, <a href="/search/physics?searchtype=author&query=Katsika%2C+K">K. Katsika</a>, <a href="/search/physics?searchtype=author&query=Kawasaki%2C+S">S. Kawasaki</a>, <a href="/search/physics?searchtype=author&query=Kikawa%2C+T">T. Kikawa</a>, <a href="/search/physics?searchtype=author&query=Klassen%2C+W">W. Klassen</a>, <a href="/search/physics?searchtype=author&query=Konaka%2C+A">A. Konaka</a> , et al. (25 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="1905.08857v2-abstract-short" style="display: inline;"> A fast-switching, high-repetition-rate magnet and power supply have been developed for and operated at TRIUMF, to deliver a proton beam to the new ultracold neutron (UCN) facility. The facility possesses unique operational requirements: a time-averaged beam current of 40~$渭$A with the ability to switch the beam on or off for several minutes. These requirements are in conflict with the typical oper… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.08857v2-abstract-full').style.display = 'inline'; document.getElementById('1905.08857v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.08857v2-abstract-full" style="display: none;"> A fast-switching, high-repetition-rate magnet and power supply have been developed for and operated at TRIUMF, to deliver a proton beam to the new ultracold neutron (UCN) facility. The facility possesses unique operational requirements: a time-averaged beam current of 40~$渭$A with the ability to switch the beam on or off for several minutes. These requirements are in conflict with the typical operation mode of the TRIUMF cyclotron which delivers nearly continuous beam to multiple users. To enable the creation of the UCN facility, a beam-sharing arrangement with another facility was made. The beam sharing is accomplished by the fast-switching (kicker) magnet which is ramped in 50~$渭$s to a current of 193~A, held there for approximately 1~ms, then ramped down in the same short period of time. This achieves a 12~mrad deflection which is sufficient to switch the proton beam between the two facilities. The kicker magnet relies on a high-current, low-inductance coil connected to a fast-switching power supply that is based on insulated-gate bipolar transistors (IGBTs). The design and performance of the kicker magnet system and initial beam delivery results are reported. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.08857v2-abstract-full').style.display = 'none'; document.getElementById('1905.08857v2-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, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">16 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/1904.12650">arXiv:1904.12650</a> <span> [<a href="https://arxiv.org/pdf/1904.12650">pdf</a>, <a href="https://arxiv.org/format/1904.12650">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-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/10.3847/1538-4357/ab2fe0">10.3847/1538-4357/ab2fe0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measured reduction in Alfv茅n wave energy propagating through longitudinal gradients scaled to match solar coronal holes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bose%2C+S">Sayak Bose</a>, <a href="/search/physics?searchtype=author&query=Carter%2C+T">Troy Carter</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Tripathi%2C+S">Shreekrishna Tripathi</a>, <a href="/search/physics?searchtype=author&query=Vincena%2C+S">Stephen Vincena</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="1904.12650v2-abstract-short" style="display: inline;"> We have explored the effectiveness of a longitudinal gradient in Alfv茅n speed in reducing the energy of propagating Alfv茅n waves under conditions scaled to match solar coronal holes. The experiments were conducted in the Large Plasma Device at the University of California, Los Angeles. Our results show that the energy of the transmitted Alfv茅n wave decreases as the inhomogeneity parameter,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.12650v2-abstract-full').style.display = 'inline'; document.getElementById('1904.12650v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.12650v2-abstract-full" style="display: none;"> We have explored the effectiveness of a longitudinal gradient in Alfv茅n speed in reducing the energy of propagating Alfv茅n waves under conditions scaled to match solar coronal holes. The experiments were conducted in the Large Plasma Device at the University of California, Los Angeles. Our results show that the energy of the transmitted Alfv茅n wave decreases as the inhomogeneity parameter, $位/L_{\rm A}$, increases. Here, $位$ is the wavelength of the Alfv茅n wave and $L_{\rm A}$ is the scale length of Alfv茅n speed gradient. For gradients similar to those in coronal holes, the waves are observed to lose a factor of $\approx 5$ more energy than they do when propagating through a uniform plasma without a gradient. We have carried out further experiments and analyses to constrain the cause of wave energy reduction in the gradient. The loss of Alfv茅n wave energy from mode coupling is unlikely, as we have not detected any other modes. Contrary to theoretical expectations, the reduction in the energy of the transmitted wave is not accompanied by a detectable reflected wave. Nonlinear effects are ruled out as the amplitude of the initial wave is too small and the wave frequency well below the ion cyclotron frequency. Since the total energy must be conserved, it is possible that the lost wave energy is being deposited in the plasma. Further studies are needed to explore where the energy is going. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.12650v2-abstract-full').style.display = 'none'; document.getElementById('1904.12650v2-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 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">Journal ref:</span> ApJ 882 183 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1811.06157">arXiv:1811.06157</a> <span> [<a href="https://arxiv.org/pdf/1811.06157">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey 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="Computational Physics">physics.comp-ph</span> </div> </div> <p class="title is-5 mathjax"> Perspectives on Astrophysics Based on Atomic, Molecular, and Optical (AMO) Techniques </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</a>, <a href="/search/physics?searchtype=author&query=Babb%2C+J+F">James F. Babb</a>, <a href="/search/physics?searchtype=author&query=Bellan%2C+P+M">Paul M. Bellan</a>, <a href="/search/physics?searchtype=author&query=Brogan%2C+C">Crystal Brogan</a>, <a href="/search/physics?searchtype=author&query=Cami%2C+J">Jan Cami</a>, <a href="/search/physics?searchtype=author&query=Caselli%2C+P">Paola Caselli</a>, <a href="/search/physics?searchtype=author&query=Corrales%2C+L">Lia Corrales</a>, <a href="/search/physics?searchtype=author&query=Dominguez%2C+G">Gerardo Dominguez</a>, <a href="/search/physics?searchtype=author&query=Federman%2C+S+R">Steven R. Federman</a>, <a href="/search/physics?searchtype=author&query=Fontes%2C+C+J">Chris J. Fontes</a>, <a href="/search/physics?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/physics?searchtype=author&query=Gibson%2C+B">Brad Gibson</a>, <a href="/search/physics?searchtype=author&query=Golub%2C+L">Leon Golub</a>, <a href="/search/physics?searchtype=author&query=Gorczyca%2C+T+W">Thomas W. Gorczyca</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=H%C3%B6rst%2C+S+M">Sarah M. H枚rst</a>, <a href="/search/physics?searchtype=author&query=Hudson%2C+R+L">Reggie L. Hudson</a>, <a href="/search/physics?searchtype=author&query=Kuhn%2C+J">Jeffrey Kuhn</a>, <a href="/search/physics?searchtype=author&query=Lawler%2C+J+E">James E. Lawler</a>, <a href="/search/physics?searchtype=author&query=Leutenegger%2C+M+A">Maurice A. Leutenegger</a>, <a href="/search/physics?searchtype=author&query=Marler%2C+J+P">Joan P. Marler</a>, <a href="/search/physics?searchtype=author&query=McCarthy%2C+M+C">Michael C. McCarthy</a>, <a href="/search/physics?searchtype=author&query=McGuire%2C+B+A">Brett A. McGuire</a>, <a href="/search/physics?searchtype=author&query=Milam%2C+S+N">Stefanie N. Milam</a>, <a href="/search/physics?searchtype=author&query=Murphy%2C+N+A">Nicholas A. Murphy</a> , et al. (13 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="1811.06157v1-abstract-short" style="display: inline;"> About two generations ago, a large part of AMO science was dominated by experimental high energy collision studies and perturbative theoretical methods. Since then, AMO science has undergone a transition and is now dominated by quantum, ultracold, and ultrafast studies. But in the process, the field has passed over the complexity that lies between these two extremes. Most of the Universe resides i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.06157v1-abstract-full').style.display = 'inline'; document.getElementById('1811.06157v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1811.06157v1-abstract-full" style="display: none;"> About two generations ago, a large part of AMO science was dominated by experimental high energy collision studies and perturbative theoretical methods. Since then, AMO science has undergone a transition and is now dominated by quantum, ultracold, and ultrafast studies. But in the process, the field has passed over the complexity that lies between these two extremes. Most of the Universe resides in this intermediate region. We put forward that the next frontier for AMO science is to explore the AMO complexity that describes most of the Cosmos. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.06157v1-abstract-full').style.display = 'none'; document.getElementById('1811.06157v1-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 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">White paper submission to the Decadal Assessment and Outlook Report on Atomic, Molecular, and Optical (AMO) Science (AMO 2020)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.01001">arXiv:1810.01001</a> <span> [<a href="https://arxiv.org/pdf/1810.01001">pdf</a>, <a href="https://arxiv.org/format/1810.01001">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.2019.01.074">10.1016/j.nima.2019.01.074 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A beamline for fundamental neutron physics at TRIUMF </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Ahmed%2C+S">S. Ahmed</a>, <a href="/search/physics?searchtype=author&query=Andalib%2C+T">T. Andalib</a>, <a href="/search/physics?searchtype=author&query=Barnes%2C+M+J">M. J. Barnes</a>, <a href="/search/physics?searchtype=author&query=Bidinosti%2C+C+B">C. B. Bidinosti</a>, <a href="/search/physics?searchtype=author&query=Bylinsky%2C+Y">Y. Bylinsky</a>, <a href="/search/physics?searchtype=author&query=Chak%2C+J">J. Chak</a>, <a href="/search/physics?searchtype=author&query=Das%2C+M">M. Das</a>, <a href="/search/physics?searchtype=author&query=Davis%2C+C+A">C. A. Davis</a>, <a href="/search/physics?searchtype=author&query=Franke%2C+B">B. Franke</a>, <a href="/search/physics?searchtype=author&query=Gericke%2C+M+T+W">M. T. W. Gericke</a>, <a href="/search/physics?searchtype=author&query=Giampa%2C+P">P. Giampa</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Hansen-Romu%2C+S">S. Hansen-Romu</a>, <a href="/search/physics?searchtype=author&query=Hatanaka%2C+K">K. Hatanaka</a>, <a href="/search/physics?searchtype=author&query=Jamieson%2C+B">B. Jamieson</a>, <a href="/search/physics?searchtype=author&query=Jones%2C+D">D. Jones</a>, <a href="/search/physics?searchtype=author&query=Katsika%2C+K">K. Katsika</a>, <a href="/search/physics?searchtype=author&query=Kawasaki%2C+S">S. Kawasaki</a>, <a href="/search/physics?searchtype=author&query=Klassen%2C+W">W. Klassen</a>, <a href="/search/physics?searchtype=author&query=Konaka%2C+A">A. Konaka</a>, <a href="/search/physics?searchtype=author&query=Korkmaz%2C+E">E. Korkmaz</a>, <a href="/search/physics?searchtype=author&query=Kuchler%2C+F">F. Kuchler</a>, <a href="/search/physics?searchtype=author&query=Kurchaninov%2C+L">L. Kurchaninov</a>, <a href="/search/physics?searchtype=author&query=Lang%2C+M">M. Lang</a>, <a href="/search/physics?searchtype=author&query=Lee%2C+L">L. Lee</a> , et al. (22 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="1810.01001v2-abstract-short" style="display: inline;"> This article describes the new primary proton beamline 1U at TRIUMF. The purpose of this beamline is to produce ultracold neutrons (UCN) for fundamental-physics experiments. It delivers up to 40 microA of 480 MeV protons from the TRIUMF cyclotron to a tungsten spallation target and uses a fast kicker to share the beam between the Center for Molecular and Materials Science and UCN. The beamline has… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.01001v2-abstract-full').style.display = 'inline'; document.getElementById('1810.01001v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.01001v2-abstract-full" style="display: none;"> This article describes the new primary proton beamline 1U at TRIUMF. The purpose of this beamline is to produce ultracold neutrons (UCN) for fundamental-physics experiments. It delivers up to 40 microA of 480 MeV protons from the TRIUMF cyclotron to a tungsten spallation target and uses a fast kicker to share the beam between the Center for Molecular and Materials Science and UCN. The beamline has been successfully commissioned and operated with a beam current up to 10 microA, facilitating first large-scale UCN production in Canada. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.01001v2-abstract-full').style.display = 'none'; document.getElementById('1810.01001v2-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 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1708.02155">arXiv:1708.02155</a> <span> [<a href="https://arxiv.org/pdf/1708.02155">pdf</a>, <a href="https://arxiv.org/ps/1708.02155">ps</a>, <a href="https://arxiv.org/format/1708.02155">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 Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.3847/1538-4357/aa9276">10.3847/1538-4357/aa9276 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electron-Impact Multiple Ionization Cross Sections for Atoms and Ions of Helium through Zinc </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Mueller%2C+A">Alfred Mueller</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="1708.02155v1-abstract-short" style="display: inline;"> We have compiled a set of electron-impact multiple ionization (EIMI) cross sections for astrophysically relevant ions. EIMI can have a significant effect on the ionization balance of non-equilibrium plasmas. For example, it can be important if there is a rapid change in the electron temperature or if there is a non-thermal electron energy distribution, such as a kappa distribution. Cross sections… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1708.02155v1-abstract-full').style.display = 'inline'; document.getElementById('1708.02155v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1708.02155v1-abstract-full" style="display: none;"> We have compiled a set of electron-impact multiple ionization (EIMI) cross sections for astrophysically relevant ions. EIMI can have a significant effect on the ionization balance of non-equilibrium plasmas. For example, it can be important if there is a rapid change in the electron temperature or if there is a non-thermal electron energy distribution, such as a kappa distribution. Cross sections for EIMI are needed in order to account for these processes in plasma modeling and for spectroscopic interpretation. Here, we describe our comparison of proposed semiempirical formulae to the available experimental EIMI cross section data. Based on this comparison, we have interpolated and extrapolated fitting parameters to systems that have not yet been measured. A tabulation of the fit parameters is provided for 3466 EIMI cross sections. We also highlight some outstanding issues that remain to be resolved. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1708.02155v1-abstract-full').style.display = 'none'; document.getElementById('1708.02155v1-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 August, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2017. </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">Submitted to Astrophysical Journal Supplement. The cross section database (Table 2 in the manuscript) is available upon request</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1511.02013">arXiv:1511.02013</a> <span> [<a href="https://arxiv.org/pdf/1511.02013">pdf</a>, <a href="https://arxiv.org/ps/1511.02013">ps</a>, <a href="https://arxiv.org/format/1511.02013">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1088/0953-4075/49/7/074004">10.1088/0953-4075/49/7/074004 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Absolute rate coefficients for photorecombination of berylliumlike and boronlike silicon ions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Becker%2C+A">A. Becker</a>, <a href="/search/physics?searchtype=author&query=Brandau%2C+C">C. Brandau</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</a>, <a href="/search/physics?searchtype=author&query=Spruck%2C+K">K. Spruck</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</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="1511.02013v2-abstract-short" style="display: inline;"> We report measured rate coefficients for electron-ion recombination for Si10+ forming Si9+ and for Si9+ forming Si8+, respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring. Electron-ion collision energies ranged from 0 to 50 eV for Si9+ and from 0 to 2000 eV for Si10+, thus, extending previous measurements for Si10+ [Orban et al. 20… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.02013v2-abstract-full').style.display = 'inline'; document.getElementById('1511.02013v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.02013v2-abstract-full" style="display: none;"> We report measured rate coefficients for electron-ion recombination for Si10+ forming Si9+ and for Si9+ forming Si8+, respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring. Electron-ion collision energies ranged from 0 to 50 eV for Si9+ and from 0 to 2000 eV for Si10+, thus, extending previous measurements for Si10+ [Orban et al. 2010, Astrophys. J. 721, 1603] to much higher energies. Experimentally derived rate coefficients for the recombination of Si9+ and Si10+ ions in a plasma are presented along with simple parameterizations. These rate coefficients are useful for the modeling of the charge balance of silicon in photoionized plasmas (Si9+ and Si10+) and in collisionally ionized plasmas (Si10+ only). In the corresponding temperature ranges, the experimentally derived rate coefficients agree with the latest corresponding theoretical results within the experimental uncertainties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.02013v2-abstract-full').style.display = 'none'; document.getElementById('1511.02013v2-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, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 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">17 pages, 7 figures, 3 tables, 66 references, submitted to the J. Phys. B special issue on atomic and molecular data for astrophysicists</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1507.04216">arXiv:1507.04216</a> <span> [<a href="https://arxiv.org/pdf/1507.04216">pdf</a>, <a href="https://arxiv.org/ps/1507.04216">ps</a>, <a href="https://arxiv.org/format/1507.04216">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</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/10.1088/0004-637X/813/1/16">10.1088/0004-637X/813/1/16 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Storage Ring Cross Section Measurements for Electron Impact Ionization of Fe 7+ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Becker%2C+A">A. Becker</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</a>, <a href="/search/physics?searchtype=author&query=Spruck%2C+K">K. Spruck</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</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="1507.04216v1-abstract-short" style="display: inline;"> We have measured electron impact ionization (EII) for Fe 7+ from the ionization threshold up to 1200 eV. The measurements were performed using the TSR heavy ion storage ring. The ions were stored long enough prior to measurement to remove most metastables, resulting in a beam of 94% ground state ions. Comparing with the previously recommended atomic data, we find that the Arnaud & Raymond (1992) c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1507.04216v1-abstract-full').style.display = 'inline'; document.getElementById('1507.04216v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1507.04216v1-abstract-full" style="display: none;"> We have measured electron impact ionization (EII) for Fe 7+ from the ionization threshold up to 1200 eV. The measurements were performed using the TSR heavy ion storage ring. The ions were stored long enough prior to measurement to remove most metastables, resulting in a beam of 94% ground state ions. Comparing with the previously recommended atomic data, we find that the Arnaud & Raymond (1992) cross section is up to about 40\% larger than our measurement, with the largest discrepancies below about 400~eV. The cross section of Dere (2007) agrees to within 10%, which is about the magnitude of the experimental uncertainties. The remaining discrepancies between measurement and the most recent theory are likely due to shortcomings in the theoretical treatment of the excitation-autoionization contribution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1507.04216v1-abstract-full').style.display = 'none'; document.getElementById('1507.04216v1-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> 15 July, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">Submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1506.07127">arXiv:1506.07127</a> <span> [<a href="https://arxiv.org/pdf/1506.07127">pdf</a>, <a href="https://arxiv.org/ps/1506.07127">ps</a>, <a href="https://arxiv.org/format/1506.07127">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-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/10.1088/0004-637X/809/2/178">10.1088/0004-637X/809/2/178 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Simple Method for Modeling Collision Processes in Plasmas with a Kappa Energy Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="1506.07127v2-abstract-short" style="display: inline;"> We demonstrate that a nonthermal distribution of particles described by a kappa distribution can be accurately approximated by a weighted sum of Maxwell-Boltzmann distributions. We apply this method to modeling collision processes in kappa-distribution plasmas, with a particular focus on atomic processes important for solar physics. The relevant collision process rate coefficients are generated by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1506.07127v2-abstract-full').style.display = 'inline'; document.getElementById('1506.07127v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1506.07127v2-abstract-full" style="display: none;"> We demonstrate that a nonthermal distribution of particles described by a kappa distribution can be accurately approximated by a weighted sum of Maxwell-Boltzmann distributions. We apply this method to modeling collision processes in kappa-distribution plasmas, with a particular focus on atomic processes important for solar physics. The relevant collision process rate coefficients are generated by summing appropriately weighted Maxwellian rate coefficients. This method reproduces the rate coefficients for a kappa distribution to an estimated accuracy of better than 5%. This is equal to or better than the accuracy of rate coefficients generated using "reverse engineering" methods, which attempt to extract the needed cross sections from the published Maxwellian rate coefficient data and then reconvolve the extracted cross sections with the desired kappa distribution. Our approach of summing Maxwellian rate coefficients is easy to implement using existing spectral analysis software. Moreover, the weights in the sum of the Maxwell-Boltzmann distribution rate coefficients can be found for any value of the parameter kappa, thereby enabling one to model plasmas with a time-varying kappa. Tabulated Maxwellian fitting parameters are given for specific values of kappa from 1.7 to 100. We also provide polynomial fits to these parameters over this entire range. Several applications of our technique are presented, including the plasma equilibrium charge state distribution (CSD), predicting line ratios, modeling the influence of electron impact multiple ionization on the equilibrium CSD of kappa-distribution plasmas, and calculating the time-varying CSD of plasmas during a solar flare. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1506.07127v2-abstract-full').style.display = 'none'; document.getElementById('1506.07127v2-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 July, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 June, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">Accepted in the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1410.4850">arXiv:1410.4850</a> <span> [<a href="https://arxiv.org/pdf/1410.4850">pdf</a>, <a href="https://arxiv.org/ps/1410.4850">ps</a>, <a href="https://arxiv.org/format/1410.4850">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1088/0004-637X/800/1/68">10.1088/0004-637X/800/1/68 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Influence of Electron-Impact Multiple Ionization on Equilibrium and Dynamic Charge State Distributions: A Case Study Using Iron </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">Daniel Wolf Savin</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="1410.4850v1-abstract-short" style="display: inline;"> We describe the influence of electron-impact multiple ionization (EIMI) on the ionization balance of collisionally ionized plasmas. We are unaware of any previous ionization balance calculations that have included EIMI, which is usually assumed to be unimportant. Here, we incorporate EIMI cross-section data into calculations of both equilibrium and non-equilibrium charge-state distributions (CSDs)… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.4850v1-abstract-full').style.display = 'inline'; document.getElementById('1410.4850v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1410.4850v1-abstract-full" style="display: none;"> We describe the influence of electron-impact multiple ionization (EIMI) on the ionization balance of collisionally ionized plasmas. We are unaware of any previous ionization balance calculations that have included EIMI, which is usually assumed to be unimportant. Here, we incorporate EIMI cross-section data into calculations of both equilibrium and non-equilibrium charge-state distributions (CSDs). For equilibrium CSDs, we find that EIMI has only a small effect and can usually be ignored. However, for non-equilibrium plasmas the influence of EIMI can be important. In particular, we find that for plasmas in which the temperature oscillates there are significant differences in the CSD when including versus neglecting EIMI. These results have implications for modeling and spectroscopy of impulsively heated plasmas, such as nanoflare heating of the solar corona. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.4850v1-abstract-full').style.display = 'none'; document.getElementById('1410.4850v1-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> 17 October, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">Submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1409.2458">arXiv:1409.2458</a> <span> [<a href="https://arxiv.org/pdf/1409.2458">pdf</a>, <a href="https://arxiv.org/ps/1409.2458">ps</a>, <a href="https://arxiv.org/format/1409.2458">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-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/10.1103/PhysRevA.90.032715">10.1103/PhysRevA.90.032715 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Recombination of W18+ ions with electrons: Absolute rate coefficients from a storage-ring experiment and from theoretical calculations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Spruck%2C+K">K. Spruck</a>, <a href="/search/physics?searchtype=author&query=Badnell%2C+N+R">N. R. Badnell</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Becker%2C+A">A. Becker</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</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="1409.2458v1-abstract-short" style="display: inline;"> We present new experimentally measured and theoretically calculated rate coefficients for the electron-ion recombination of W$^{18+}$([Kr] $4d^{10}$ $4f^{10}$) forming W$^{17+}$. At low electron-ion collision energies, the merged-beam rate coefficient is dominated by strong, mutually overlapping, recombination resonances. In the temperature range where the fractional abundance of W$^{18+}$ is expe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1409.2458v1-abstract-full').style.display = 'inline'; document.getElementById('1409.2458v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1409.2458v1-abstract-full" style="display: none;"> We present new experimentally measured and theoretically calculated rate coefficients for the electron-ion recombination of W$^{18+}$([Kr] $4d^{10}$ $4f^{10}$) forming W$^{17+}$. At low electron-ion collision energies, the merged-beam rate coefficient is dominated by strong, mutually overlapping, recombination resonances. In the temperature range where the fractional abundance of W$^{18+}$ is expected to peak in a fusion plasma, the experimentally derived Maxwellian recombination rate coefficient is 5 to 10 times larger than that which is currently recommended for plasma modeling. The complexity of the atomic structure of the open-$4f$-system under study makes the theoretical calculations extremely demanding. Nevertheless, the results of new Breit-Wigner partitioned dielectronic recombination calculations agree reasonably well with the experimental findings. This also gives confidence in the ability of the theory to generate sufficiently accurate atomic data for the plasma modeling of other complex ions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1409.2458v1-abstract-full').style.display = 'none'; document.getElementById('1409.2458v1-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> 8 September, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">11 pages, 4 figures, 2 tables, 40 references, accepted for publication in Physical Review A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A 90 (2014) 032715 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1406.1679">arXiv:1406.1679</a> <span> [<a href="https://arxiv.org/pdf/1406.1679">pdf</a>, <a href="https://arxiv.org/ps/1406.1679">ps</a>, <a href="https://arxiv.org/format/1406.1679">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1103/PhysRevA.90.012702">10.1103/PhysRevA.90.012702 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Absolute rate coefficients for photorecombination and electron-impact ionization of magnesium-like iron ions from measurements at a heavy-ion storage ring </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Becker%2C+A">A. Becker</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</a>, <a href="/search/physics?searchtype=author&query=Spruck%2C+K">K. Spruck</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</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="1406.1679v1-abstract-short" style="display: inline;"> Rate coefficients for photorecombination (PR) and cross sections for electron-impact ionization (EII) of Fe$^{14+}$ forming Fe$^{13+}$ and Fe$^{15+}$, respectively, have been measured by employing the electron-ion merged-beams technique at a heavy-ion storage ring. Rate coefficients for PR and EII of Fe$^{14+}$ ions in a plasma are derived from the experimental measurements. Simple parametrization… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1406.1679v1-abstract-full').style.display = 'inline'; document.getElementById('1406.1679v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1406.1679v1-abstract-full" style="display: none;"> Rate coefficients for photorecombination (PR) and cross sections for electron-impact ionization (EII) of Fe$^{14+}$ forming Fe$^{13+}$ and Fe$^{15+}$, respectively, have been measured by employing the electron-ion merged-beams technique at a heavy-ion storage ring. Rate coefficients for PR and EII of Fe$^{14+}$ ions in a plasma are derived from the experimental measurements. Simple parametrizations of the experimentally derived plasma rate coefficients are provided for use in the modeling of photoionized and collisionally ionized plasmas. In the temperature ranges where Fe$^{14+}$ is expected to form in such plasmas the latest theoretical rate coefficients of Altun et al. [Astron. Astrophys. 474, 1051 (2007)] for PR and of Dere [Astron. Astrophys. 466, 771 (2007)] for EII agree with the experimental results to within the experimental uncertainties. Common features in the PR and EII resonance structures are identified and discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1406.1679v1-abstract-full').style.display = 'none'; document.getElementById('1406.1679v1-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 June, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">12 pages, 6 figures, 3 tables, submitted for publication to Physical Review A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. rev. A 90 (2014) 012702 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1402.2964">arXiv:1402.2964</a> <span> [<a href="https://arxiv.org/pdf/1402.2964">pdf</a>, <a href="https://arxiv.org/ps/1402.2964">ps</a>, <a href="https://arxiv.org/format/1402.2964">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1088/1742-6596/488/1/012050">10.1088/1742-6596/488/1/012050 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electron Impact Ionization of Stored Highly Charged Ions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">Michael Hahn</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="1402.2964v1-abstract-short" style="display: inline;"> Accurate cross section data for electron impact ionization (EII) are needed in order to interpret the spectra of collisionally ionized plasmas both in astrophysics and in the laboratory. Models and spectroscopic diagnostics of such plasmas rely on accurate ionization balance calculations, which depend, in turn, on the underlying rates for EII and electron-ion recombination. EII measurements have b… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.2964v1-abstract-full').style.display = 'inline'; document.getElementById('1402.2964v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1402.2964v1-abstract-full" style="display: none;"> Accurate cross section data for electron impact ionization (EII) are needed in order to interpret the spectra of collisionally ionized plasmas both in astrophysics and in the laboratory. Models and spectroscopic diagnostics of such plasmas rely on accurate ionization balance calculations, which depend, in turn, on the underlying rates for EII and electron-ion recombination. EII measurements have been carried out using the TSR storage ring located at the Max-Planck-Institut fuer Kernphysik in Heidelberg, Germany. Storage ring measurements are largely free of metastable contamination, resulting in unambiguous EII data, unlike what is encountered with other experimental geometries. As it is impractical to perform experiments for every ion, theory must provide the bulk of the necessary EII data. In order to guide theory, TSR experiments have focused on providing at least one measurement for every isoelectronic sequence. EII data have been measured for ions from 13 isoelectronic sequences: Li-like silicon and chlorine, Be-like sulfur, B-like magnesium, and F-like through K-like iron. These experimental results provide an important benchmark for EII theory. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.2964v1-abstract-full').style.display = 'none'; document.getElementById('1402.2964v1-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 February, 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">Accepted for Journal of Physics Conference Series</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1302.6107">arXiv:1302.6107</a> <span> [<a href="https://arxiv.org/pdf/1302.6107">pdf</a>, <a href="https://arxiv.org/ps/1302.6107">ps</a>, <a href="https://arxiv.org/format/1302.6107">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1088/0004-637X/767/1/47">10.1088/0004-637X/767/1/47 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Storage Ring Cross Section Measurements for Electron Impact Single and Double Ionization of Fe^13+ and Single Ionization of Fe^16+ and Fe^17+ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Becker%2C+A">A. Becker</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</a>, <a href="/search/physics?searchtype=author&query=Spruck%2C+K">K. Spruck</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</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="1302.6107v1-abstract-short" style="display: inline;"> We report measurements of electron impact ionization (EII) for Fe^13+, Fe^16+, and Fe^17+ over collision energies from below threshold to above 3000 eV. The ions were recirculated using an ion storage ring. Data were collected after a sufficiently long time that essentially all the ions had relaxed radiatively to their ground state before data were collected. For single ionization of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.6107v1-abstract-full').style.display = 'inline'; document.getElementById('1302.6107v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1302.6107v1-abstract-full" style="display: none;"> We report measurements of electron impact ionization (EII) for Fe^13+, Fe^16+, and Fe^17+ over collision energies from below threshold to above 3000 eV. The ions were recirculated using an ion storage ring. Data were collected after a sufficiently long time that essentially all the ions had relaxed radiatively to their ground state before data were collected. For single ionization of $\fethirteen$ we find that previous single pass experiments are more than 40% larger than our results. Compared to our work, the theoretical cross section recommended by Arnaud & Raymond (1992) is more than 30% larger, while that of Dere (2007) is about 20% greater. Much of the discrepancy with Dere (2007) is due to the theory overestimating the contribution of excitation-autoionization via n=2 excitations. Double ionization of Fe^13+ is dominated by direct ionization of an inner shell electron accompanied by autoionization of a second electron. Our results for single ionization of Fe^16+ and Fe^17+ agree with theoretical calculations to within the experimental uncertainties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.6107v1-abstract-full').style.display = 'none'; document.getElementById('1302.6107v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for the Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J. 767 (2013) 47 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1204.6215">arXiv:1204.6215</a> <span> [<a href="https://arxiv.org/pdf/1204.6215">pdf</a>, <a href="https://arxiv.org/ps/1204.6215">ps</a>, <a href="https://arxiv.org/format/1204.6215">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 Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1088/0004-637X/753/1/57">10.1088/0004-637X/753/1/57 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electron-ion Recombination of Fe XII forming Fe XI: Laboratory Measurements and Theoretical Calculations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Badnell%2C+N+R">N. R. Badnell</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</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="1204.6215v1-abstract-short" style="display: inline;"> We have measured electron-ion recombination for Fe XII forming Fe XI using a merged beams configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged beams recombination rate coefficient (MBRRC) for collision energies from 0 to 1500 eV is presented. This work uses a new method for determining the absolute MBRRC… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1204.6215v1-abstract-full').style.display = 'inline'; document.getElementById('1204.6215v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1204.6215v1-abstract-full" style="display: none;"> We have measured electron-ion recombination for Fe XII forming Fe XI using a merged beams configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged beams recombination rate coefficient (MBRRC) for collision energies from 0 to 1500 eV is presented. This work uses a new method for determining the absolute MBRRC based on a comparison of the ion beam decay rate with and without the electron beam on. For energies below 75 eV, the spectrum is dominated by dielectronic recombination (DR) resonances associated with 3s-3p and 3p-3d core excitations. At higher energies we observe contributions from 3-N' and 2-N' core excitations DR. We compare our experimental results to state-of-the-art multi-configuration Breit-Pauli (MCBP) calculations and find significant differences, both in resonance energies and strengths. We have extracted the DR contributions from the measured MBRRC data and transformed them into a plasma recombination rate coefficient (PRRC) for temperatures in the range of 10^3 to 10^7 K. We show that the previously recommended DR data for Fe XII significantly underestimate the PRRC at temperatures relevant for both photoionized plasmas (PPs) and collisionaly ionized plasmas (CPs). This is to be contrasted with our MCBP PRRC results which agree with the experiment to within 30% at PP temperatures and even better at CP temperatures. We find this agreement despite the disagreement shown by the detailed comparison between our MCBP and experimental MBRRC results. Lastly, we present a simple parameterized form of the experimentally derived PRRC for easy use in astrophysical modelling codes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1204.6215v1-abstract-full').style.display = 'none'; document.getElementById('1204.6215v1-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 April, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">April 24, 2012: accepted for publication in The Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 753 (2012) 57 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1111.7317">arXiv:1111.7317</a> <span> [<a href="https://arxiv.org/pdf/1111.7317">pdf</a>, <a href="https://arxiv.org/ps/1111.7317">ps</a>, <a href="https://arxiv.org/format/1111.7317">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1103/PhysRevA.85.012513">10.1103/PhysRevA.85.012513 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Storage-ring measurement of the hyperfine-induced 2s 2p 3P0 -> 2s2 1S0 transition rate in beryllium-like sulfur </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</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="1111.7317v1-abstract-short" style="display: inline;"> The hyperfine induced 2s 2p 3P0 -> 2s2 1S0 transition rate in Be-like sulfur was measured by monitoring the decay of isotopically pure beams of 32-S12+ and 33-S12+ ions in a heavy-ion storage ring. Within the 4% experimental uncertainty the experimental value of 0.096(4)/s agrees with the most recent theoretical results of Cheng et al. [Phys. Rev. A 77, 052504 (2008)] and Andersson et al. [Phys. R… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1111.7317v1-abstract-full').style.display = 'inline'; document.getElementById('1111.7317v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1111.7317v1-abstract-full" style="display: none;"> The hyperfine induced 2s 2p 3P0 -> 2s2 1S0 transition rate in Be-like sulfur was measured by monitoring the decay of isotopically pure beams of 32-S12+ and 33-S12+ ions in a heavy-ion storage ring. Within the 4% experimental uncertainty the experimental value of 0.096(4)/s agrees with the most recent theoretical results of Cheng et al. [Phys. Rev. A 77, 052504 (2008)] and Andersson et al. [Phys. Rev. A 79, 032501 (2009)]. Repeated experiments with different magnetic fields in the storage-ring bending magnets demonstrate that artificial quenching of the 2s 2p 3P0 state by these magnetic fields is negligible. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1111.7317v1-abstract-full').style.display = 'none'; document.getElementById('1111.7317v1-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 November, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">11 pages, 7 figures, 5 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 85 (2012) 012513 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1101.2144">arXiv:1101.2144</a> <span> [<a href="https://arxiv.org/pdf/1101.2144">pdf</a>, <a href="https://arxiv.org/ps/1101.2144">ps</a>, <a href="https://arxiv.org/format/1101.2144">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 Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-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/10.1088/0004-637X/729/1/76">10.1088/0004-637X/729/1/76 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Storage Ring Cross Section Measurements for Electron Impact Ionization of Fe^11+ Forming Fe^12+ and Fe^13+ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=Mueller%2C+A">A. Mueller</a>, <a href="/search/physics?searchtype=author&query=Novotny%2C+O">O. Novotny</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</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="1101.2144v1-abstract-short" style="display: inline;"> We report ionization cross section measurements for electron impact single ionization (EISI) of Fe^11+$ forming Fe^12+ and electron impact double ionization (EIDI) of Fe^11+ forming Fe^13+. The measurements cover the center-of-mass energy range from approximately 230 eV to 2300 eV. The experiment was performed using the heavy ion storage ring TSR located at the Max-Planck-Institut fur Kernphysik i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.2144v1-abstract-full').style.display = 'inline'; document.getElementById('1101.2144v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1101.2144v1-abstract-full" style="display: none;"> We report ionization cross section measurements for electron impact single ionization (EISI) of Fe^11+$ forming Fe^12+ and electron impact double ionization (EIDI) of Fe^11+ forming Fe^13+. The measurements cover the center-of-mass energy range from approximately 230 eV to 2300 eV. The experiment was performed using the heavy ion storage ring TSR located at the Max-Planck-Institut fur Kernphysik in Heidelberg, Germany. The storage ring approach allows nearly all metastable levels to relax to the ground state before data collection begins. We find that the cross section for single ionization is 30% smaller than was previously measured in a single pass experiment using an ion beam with an unknown metastable fraction. We also find some significant differences between our experimental cross section for single ionization and recent distorted wave (DW) calculations. The DW Maxwellian EISI rate coefficient for Fe^11+ forming Fe^12+ may be underestimated by as much as 25% at temperatures for which Fe^11+ is abundant in collisional ionization equilibrium. This is likely due to the absence of 3s excitation-autoionization (EA) in the calculations. However, a precise measurement of the cross section due to this EA channel was not possible because this process is not distinguishable experimentally from electron impact excitation of an n=3 electron to levels of n > 44 followed by field ionization in the charge state analyzer after the interaction region. Our experimental results also indicate that the double ionization cross section is dominated by the indirect process in which direct single ionization of an inner shell 2l electron is followed by autoionization resulting in a net double ionization. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.2144v1-abstract-full').style.display = 'none'; document.getElementById('1101.2144v1-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, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">Accepted for publication in Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J. 729 (2011) 76 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1101.0719">arXiv:1101.0719</a> <span> [<a href="https://arxiv.org/pdf/1101.0719">pdf</a>, <a href="https://arxiv.org/ps/1101.0719">ps</a>, <a href="https://arxiv.org/format/1101.0719">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-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/10.1103/PhysRevA.83.012711">10.1103/PhysRevA.83.012711 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dielectronic recombination of xenonlike tungsten ions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Schippers%2C+S">S. Schippers</a>, <a href="/search/physics?searchtype=author&query=Bernhardt%2C+D">D. Bernhardt</a>, <a href="/search/physics?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/physics?searchtype=author&query=Krantz%2C+C">C. Krantz</a>, <a href="/search/physics?searchtype=author&query=Grieser%2C+M">M. Grieser</a>, <a href="/search/physics?searchtype=author&query=Repnow%2C+R">R. Repnow</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+A">A. Wolf</a>, <a href="/search/physics?searchtype=author&query=Lestinsky%2C+M">M. Lestinsky</a>, <a href="/search/physics?searchtype=author&query=Hahn%2C+M">M. Hahn</a>, <a href="/search/physics?searchtype=author&query=Novotn%C3%BD%2C+O">O. Novotn媒</a>, <a href="/search/physics?searchtype=author&query=Savin%2C+D+W">D. W. Savin</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="1101.0719v1-abstract-short" style="display: inline;"> Dielectronic recombination (DR) of xenonlike W20+ forming W19+ has been studied experimentally at a heavy-ion storage-ring. A merged-beams method has been employed for obtaining absolute rate coefficients for electron-ion recombination in the collision energy range 0-140 eV. The measured rate coefficient is dominated by strong DR resonances even at the lowest experimental energies. At plasma tempe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.0719v1-abstract-full').style.display = 'inline'; document.getElementById('1101.0719v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1101.0719v1-abstract-full" style="display: none;"> Dielectronic recombination (DR) of xenonlike W20+ forming W19+ has been studied experimentally at a heavy-ion storage-ring. A merged-beams method has been employed for obtaining absolute rate coefficients for electron-ion recombination in the collision energy range 0-140 eV. The measured rate coefficient is dominated by strong DR resonances even at the lowest experimental energies. At plasma temperatures where the fractional abundance of W20+ is expected to peak in a fusion plasma, the experimentally derived plasma recombination rate coefficient is over a factor of 4 larger than the theoretically-calculated rate coefficient which is currently used in fusion plasma modeling. The largest part of this discrepancy stems most probably from the neglect in the theoretical calculations of DR associated with fine-structure excitations of the W20+([Kr] 4d10 4f8) ion core. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.0719v1-abstract-full').style.display = 'none'; document.getElementById('1101.0719v1-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 January, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">7 pagers, 4 figures, accepted for publication in Physical Review A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 83 (2011) 012711 </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 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg> <a href="https://info.arxiv.org/help/contact.html"> Contact</a> </li> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>subscribe to arXiv mailings</title><desc>Click here to subscribe</desc><path d="M476 3.2L12.5 270.6c-18.1 10.4-15.8 35.6 2.2 43.2L121 358.4l287.3-253.2c5.5-4.9 13.3 2.6 8.6 8.3L176 407v80.5c0 23.6 28.5 32.9 42.5 15.8L282 426l124.6 52.2c14.2 6 30.4-2.9 33-18.2l72-432C515 7.8 493.3-6.8 476 3.2z"/></svg> <a href="https://info.arxiv.org/help/subscribe"> Subscribe</a> </li> </ul> </div> </div> </div>   <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/license/index.html">Copyright</a></li> <li><a href="https://info.arxiv.org/help/policies/privacy_policy.html">Privacy Policy</a></li> </ul> </div> <div class="column sorry-app-links"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/web_accessibility.html">Web Accessibility Assistance</a></li> <li> <p class="help"> <a class="a11y-main-link" href="https://status.arxiv.org" target="_blank">arXiv Operational Status <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" class="icon filter-dark_grey" role="presentation"><path d="M224.3 273l-136 136c-9.4 9.4-24.6 9.4-33.9 0l-22.6-22.6c-9.4-9.4-9.4-24.6 0-33.9l96.4-96.4-96.4-96.4c-9.4-9.4-9.4-24.6 0-33.9L54.3 103c9.4-9.4 24.6-9.4 33.9 0l136 136c9.5 9.4 9.5 24.6.1 34z"/></svg></a><br> Get status notifications via <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/email/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg>email</a> or <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/slack/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" class="icon filter-black" role="presentation"><path d="M94.12 315.1c0 25.9-21.16 47.06-47.06 47.06S0 341 0 315.1c0-25.9 21.16-47.06 47.06-47.06h47.06v47.06zm23.72 0c0-25.9 21.16-47.06 47.06-47.06s47.06 21.16 47.06 47.06v117.84c0 25.9-21.16 47.06-47.06 47.06s-47.06-21.16-47.06-47.06V315.1zm47.06-188.98c-25.9 0-47.06-21.16-47.06-47.06S139 32 164.9 32s47.06 21.16 47.06 47.06v47.06H164.9zm0 23.72c25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06H47.06C21.16 243.96 0 222.8 0 196.9s21.16-47.06 47.06-47.06H164.9zm188.98 47.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06h-47.06V196.9zm-23.72 0c0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06V79.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06V196.9zM283.1 385.88c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06v-47.06h47.06zm0-23.72c-25.9 0-47.06-21.16-47.06-47.06 0-25.9 21.16-47.06 47.06-47.06h117.84c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06H283.1z"/></svg>slack</a> </p> </li> </ul> </div> </div> </div>  </div> </footer> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/member_acknowledgement.js"></script> </body> </html>

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