Observation of two-neutrino double electron capture in 124Xe with XENON1T

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Until now, indications of 2νECEC decays have only been seen for two isotopes2–5, 78Kr and 130Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance6,7. The 2νECEC half-life is an important observable for nuclear structure models8–14 and its measurement represents a meaningful step in the search for neutrinoless double electron capture—the detection of which would establish the Majorana nature of the neutrino and would give access to the absolute neutrino mass15–17. Here we report the direct observation of 2νECEC in 124Xe with the XENON1T dark-matter detector. The significance of the signal is 4.4 standard deviations and the corresponding half-life of 1.8 × 1022 years (statistical uncertainty, 0.5 × 1022 years; systematic uncertainty, 0.1 × 1022 years) is the longest measured directly so far. This study demonstrates that the low background and large target mass of xenon-based dark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments18–20. Two-neutrino double electron capture is observed experimentally in 124Xe with the XENON1T detector, yielding a half-life of 1.8 × 1022 years.","datePublished":"2019-04-24T00:00:00Z","dateModified":"2019-04-24T00:00:00Z","pageStart":"532","pageEnd":"535","sameAs":"https://doi.org/10.1038/s41586-019-1124-4","keywords":["Experimental nuclear physics","Experimental particle physics","Particle astrophysics","Science","Humanities and Social Sciences","multidisciplinary"],"image":["https://media.springernature.com/lw1200/springer-static/image/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig1_HTML.png","https://media.springernature.com/lw1200/springer-static/image/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig2_HTML.png","https://media.springernature.com/lw1200/springer-static/image/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig3_HTML.png","https://media.springernature.com/lw1200/springer-static/image/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig4_HTML.png"],"isPartOf":{"name":"Nature","issn":["1476-4687","0028-0836"],"volumeNumber":"568","@type":["Periodical","PublicationVolume"]},"publisher":{"name":"Nature Publishing Group UK","logo":{"url":"https://www.springernature.com/app-sn/public/images/logo-springernature.png","@type":"ImageObject"},"@type":"Organization"},"author":[],"isAccessibleForFree":false,"hasPart":{"isAccessibleForFree":false,"cssSelector":".main-content","@type":"WebPageElement"},"@type":"ScholarlyArticle"},"@context":"https://schema.org","@type":"WebPage"}</script> <link rel="canonical" href="https://www.nature.com/articles/s41586-019-1124-4"> <meta name="journal_id" content="41586"/> <meta name="dc.title" content="Observation of two-neutrino double electron capture in 124Xe with XENON1T"/> <meta name="dc.source" content="Nature 2019 568:7753"/> <meta name="dc.format" content="text/html"/> <meta name="dc.publisher" content="Nature Publishing Group"/> <meta name="dc.date" content="2019-04-24"/> <meta name="dc.type" content="OriginalPaper"/> <meta name="dc.language" content="En"/> <meta name="dc.copyright" content="2019 The Author(s), under exclusive licence to Springer Nature Limited"/> <meta name="dc.rights" content="2019 The Author(s), under exclusive licence to Springer Nature Limited"/> <meta name="dc.rightsAgent" content="journalpermissions@springernature.com"/> <meta name="dc.description" content="Two-neutrino double electron capture (2νECEC) is a second-order weak-interaction process with a predicted half-life that surpasses the age of the Universe by many orders of magnitude1. Until now, indications of 2νECEC decays have only been seen for two isotopes2–5, 78Kr and 130Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance6,7. The 2νECEC half-life is an important observable for nuclear structure models8–14 and its measurement represents a meaningful step in the search for neutrinoless double electron capture—the detection of which would establish the Majorana nature of the neutrino and would give access to the absolute neutrino mass15–17. Here we report the direct observation of 2νECEC in 124Xe with the XENON1T dark-matter detector. The significance of the signal is 4.4 standard deviations and the corresponding half-life of 1.8&nbsp;×&nbsp;1022&nbsp;years&nbsp;(statistical uncertainty, 0.5&nbsp;×&nbsp;1022&nbsp;years; systematic uncertainty, 0.1&nbsp;×&nbsp;1022&nbsp;years) is the longest measured directly so far. This study demonstrates that the low background and large target mass of xenon-based dark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments18–20. 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itemscope itemtype="https://schema.org/ListItem"> <span itemprop="name">article</span><meta itemprop="position" content="3"></li> </ol> </div> </nav> </div> <div class="u-container u-mt-32 u-mb-32 u-clearfix" id="content" data-component="article-container" data-container-type="article"> <main class="c-article-main-column u-float-left js-main-column" data-track-component="article body"> <article lang="en"> <div class="c-article-header"> <header> <ul class="c-article-identifiers" data-test="article-identifier"> <li class="c-article-identifiers__item" data-test="article-category">Letter</li> <li class="c-article-identifiers__item">Published: <time datetime="2019-04-24">24 April 2019</time></li> </ul> <h1 class="c-article-title" data-test="article-title" data-article-title="">Observation of two-neutrino double electron capture in <sup>124</sup>Xe with XENON1T</h1> <ul class="c-article-author-list c-article-author-list--short" data-test="authors-list" data-component-authors-activator="authors-list"><li class="c-article-author-list__item"><a data-test="author-name" data-author-popup="group-1" href="#group-1">XENON Collaboration*</a></li></ul> <p class="c-article-info-details" data-container-section="info"> <a data-test="journal-link" href="/" data-track="click" data-track-action="journal homepage" data-track-category="article body" data-track-label="link"><i data-test="journal-title">Nature</i></a> <b data-test="journal-volume"><span class="u-visually-hidden">volume</span> 568</b>, <span class="u-visually-hidden">pages </span>532–535 (<span data-test="article-publication-year">2019</span>)<a href="#citeas" class="c-article-info-details__cite-as u-hide-print" data-track="click" data-track-action="cite this article" data-track-label="link">Cite this article</a> </p> <div class="c-article-metrics-bar__wrapper u-clear-both"> <ul class="c-article-metrics-bar u-list-reset"> <li class=" c-article-metrics-bar__item" data-test="access-count"> <p class="c-article-metrics-bar__count">16k <span class="c-article-metrics-bar__label">Accesses</span></p> </li> <li class="c-article-metrics-bar__item" data-test="altmetric-score"> <p class="c-article-metrics-bar__count">795 <span class="c-article-metrics-bar__label">Altmetric</span></p> </li> <li class="c-article-metrics-bar__item"> <p class="c-article-metrics-bar__details"><a href="/articles/s41586-019-1124-4/metrics" data-track="click" data-track-action="view metrics" data-track-label="link" rel="nofollow">Metrics <span class="u-visually-hidden">details</span></a></p> </li> </ul> </div> </header> <div class="u-js-hide" data-component="article-subject-links"> <h3 class="c-article__sub-heading">Subjects</h3> <ul class="c-article-subject-list"> <li class="c-article-subject-list__subject"><a href="/subjects/experimental-nuclear-physics" data-track="click" data-track-action="view subject" data-track-label="link">Experimental nuclear physics</a></li><li class="c-article-subject-list__subject"><a href="/subjects/experimental-particle-physics" data-track="click" data-track-action="view subject" data-track-label="link">Experimental particle physics</a></li><li class="c-article-subject-list__subject"><a href="/subjects/particle-astrophysics" data-track="click" data-track-action="view subject" data-track-label="link">Particle astrophysics</a></li> </ul> </div> </div> <div class="c-article-body"> <section aria-labelledby="Abs1" data-title="Abstract" lang="en"><div class="c-article-section" id="Abs1-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="Abs1">Abstract</h2><div class="c-article-section__content" id="Abs1-content"><p>Two-neutrino double electron capture (2<i>ν</i>ECEC) is a second-order weak-interaction process with a predicted half-life that surpasses the age of the Universe by many orders of magnitude<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 1" title="Winter, R. G. Double K capture and single K capture with positron emission. Phys. Rev. 100, 142–144 (1955)." href="/articles/s41586-019-1124-4#ref-CR1" id="ref-link-section-d96320826e2135">1</a></sup>. Until now, indications of 2<i>ν</i>ECEC decays have only been seen for two isotopes<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Gavrilyuk, Y. M. et al. Indications of 2ν2K capture in 78Kr. Phys. Rev. C 87, 035501 (2013)." href="#ref-CR2" id="ref-link-section-d96320826e2142">2</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Ratkevich, S. S. et al. Comparative study of the double-K-shell-vacancy production in single- and double-electron-capture decay. Phys. Rev. C 96, 065502 (2017)." href="#ref-CR3" id="ref-link-section-d96320826e2142_1">3</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Meshik, A. P., Hohenberg, C. M., Pravdivtseva, O. V. & Kapusta, Y. S. Weak decay of 130Ba and 132Ba: geochemical measurements. Phys. Rev. C 64, 035205 (2001)." href="#ref-CR4" id="ref-link-section-d96320826e2142_2">4</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 5" title="Pujol, M., Marty, B., Burnard, P. & Philippot, P. Xenon in archean barite: weak decay of 130Ba, mass-dependent isotopic fractionation and implication for barite formation. Geochim. Cosmochim. Acta 73, 6834–6846 (2009)." href="/articles/s41586-019-1124-4#ref-CR5" id="ref-link-section-d96320826e2145">5</a></sup>, <sup>78</sup>Kr and <sup>130</sup>Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 6" title="Gavriljuk, Y. M. et al. 2K-capture in 124Xe: results of data processing for an exposure of 37.7 kg day. Phys. Part. Nucl. 49, 563–568 (2018)." href="/articles/s41586-019-1124-4#ref-CR6" id="ref-link-section-d96320826e2154">6</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 7" title="Abe, K. et al. Improved search for two-neutrino double electron capture on 124Xe and 126Xe using particle identification in XMASS-I. Progr. Theor. Exp. Phys. 2018, 053D03 (2018)." href="/articles/s41586-019-1124-4#ref-CR7" id="ref-link-section-d96320826e2157">7</a></sup>. The 2<i>ν</i>ECEC half-life is an important observable for nuclear structure models<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Suhonen, J. Double beta decays of 124Xe investigated in the QRPA framework. J. Phys. G Nucl. Phys. 40, 075102 (2013)." href="#ref-CR8" id="ref-link-section-d96320826e2164">8</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Aunola, M. & Suhonen, J. Systematic study of beta and double beta decay to excited final states. Nucl. Phys. A 602, 133–166 (1996)." href="#ref-CR9" id="ref-link-section-d96320826e2164_1">9</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Singh, S., Chandra, R., Rath, P. K., Raina, P. K. & Hirsch, J. G. 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 (2018)." href="/articles/s41586-019-1124-4#ref-CR14" id="ref-link-section-d96320826e2167">14</a></sup> and its measurement represents a meaningful step in the search for neutrinoless double electron capture—the detection of which would establish the Majorana nature of the neutrino and would give access to the absolute neutrino mass<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Majorana, E. Theory of the symmetry of electrons and positrons. Nuovo Cimento 14, 171–184 (1937)." href="#ref-CR15" id="ref-link-section-d96320826e2171">15</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Bernabeu, J., De Rujula, A. & Jarlskog, C. Neutrinoless double electron capture as a tool to measure the ν
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This study demonstrates that the low background and large target mass of xenon-based dark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Aprile, E. et al. Physics reach of the XENON1T dark matter experiment. J. Cosmol. Astropart. Phys. 1604, 027 (2016)." href="#ref-CR18" id="ref-link-section-d96320826e2190">18</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" title="Mount, B. J. et al. LUX-ZEPLIN (LZ). Report No. LBNL-1007256 (Lawrence Berkeley National Laboratory, 2017)." href="#ref-CR19" id="ref-link-section-d96320826e2190_1">19</a>,<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 20" title="Aalbers, J. et al. DARWIN: towards the ultimate dark matter detector. J. Cosmol. Astropart. Phys. 1611, 017 (2016)." href="/articles/s41586-019-1124-4#ref-CR20" id="ref-link-section-d96320826e2193">20</a></sup>.</p></div></div></section> <noscript> <div class="c-nature-box c-nature-box--side " data-component="entitlement-box"> <div class="js-access-button"> <a href="https://wayf.springernature.com?redirect_uri=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41586-019-1124-4" class="c-article__button" data-test="ra21"> <svg class="u-icon" width="18" height="18" aria-hidden="true" focusable="false"><use href="#icon-institution"></use></svg> <span class="c-article__button-text">Access through your institution</span> </a> </div> <div class="js-buy-button"> <a href="#access-options" class="c-article__button c-article__button--inverted" data-test="ra21"> <span>Buy or subscribe</span> </a> </div> </div> </noscript> <div class="js-context-bar-sticky-point-mobile" data-track-context="article body"> </div> <div class="c-article-access-provider u-mb-32 u-mt-0"> <p 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Menéndez for sharing his expertise in the theory of double β decay. We gratefully acknowledge support from the National Science Foundation, Swiss National Science Foundation, German Ministry for Education and Research, Max Planck Gesellschaft, Deutsche Forschungsgemeinschaft, Netherlands Organisation for Scientific Research (NWO), NLeSC, Weizmann Institute of Science, I-CORE, Pazy-Vatat, Initial Training Network Invisibles (Marie Curie Actions, PITNGA-2011-289442), Fundacao para a Ciencia e a Tecnologia, Region des Pays de la Loire, Knut and Alice Wallenberg Foundation, Kavli Foundation, Abeloe Graduate Fellowship, and Istituto Nazionale di Fisica Nucleare. Data processing was performed using infrastructures of the Open Science Grid and European Grid Initiative. We are grateful to Laboratori Nazionali del Gran Sasso for hosting and supporting the XENON project. B.K. was also at Albert Einstein Center for Fundamental Physics, University of Bern, Bern, Switzerland. S.K. is also at Kobayashi-Maskawa Institute, Nagoya University, Nagoya, Japan. J.A.M.L. is also at Coimbra Polytechnic – ISEC, Coimbra, Portugal.</p> <h3 class="c-article__sub-heading" id="FPar4">Reviewer information</h3> <p><i>Nature</i> thanks Jouni Suhonen and the other anonymous reviewer(s) for their contribution to the peer review of this work.</p> </div></div></section><section aria-labelledby="author-information" data-title="Author information"><div class="c-article-section" id="author-information-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="author-information">Author information</h2><div class="c-article-section__content" id="author-information-content"><span class="c-article-author-information__subtitle u-visually-hidden" id="author-notes">Author notes</span><ol class="c-article-author-information__list"><li class="c-article-author-information__item" id="na1"><p>A list of participants and their affiliations appears at the end of the paper.</p></li></ol><h3 class="c-article__sub-heading" id="affiliations">Authors and Affiliations</h3><ol class="c-article-author-affiliation__list"><li id="Aff1"><p class="c-article-author-affiliation__address">Physics Department, Columbia University, New York, NY, USA</p><p class="c-article-author-affiliation__authors-list">E. Aprile, M. Anthony, P. de Perio, F. Gao, Z. Greene, J. Howlett, Q. Lin, G. Plante, A. Rizzo, Y. Zhang & T. Zhu</p></li><li id="Aff2"><p class="c-article-author-affiliation__address">Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, Stockholm, Sweden</p><p class="c-article-author-affiliation__authors-list">J. Aalbers, V. C. Antochi, B. Bauermeister, J. Conrad, A. D. Ferella, J. Mahlstedt, K. Morå & B. Pelssers</p></li><li id="Aff3"><p class="c-article-author-affiliation__address">Nikhef and the University of Amsterdam, Science Park, Amsterdam, The Netherlands</p><p class="c-article-author-affiliation__authors-list">J. Aalbers, P. A. Breur, A. Brown, A. P. Colijn, M. P. Decowski & E. Hogenbirk</p></li><li id="Aff4"><p class="c-article-author-affiliation__address">Department of Physics and Astronomy, University of Bologna and INFN-Bologna, Bologna, Italy</p><p class="c-article-author-affiliation__authors-list">F. Agostini, P. Di Gangi, M. Garbini, G. Sartorelli & M. Selvi</p></li><li id="Aff5"><p class="c-article-author-affiliation__address">Institut für Physik & Exzellenzcluster PRISMA, Johannes Gutenberg-Universität Mainz, Mainz, Germany</p><p class="c-article-author-affiliation__authors-list">M. Alfonsi, U. Oberlack, M. Scheibelhut, S. Schindler & D. Wenz</p></li><li id="Aff6"><p class="c-article-author-affiliation__address">Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany</p><p class="c-article-author-affiliation__authors-list">L. Althueser, A. Fieguth, M. Murra, D. Schulte, M. Vargas, C. Weinheimer & C. Wittweg</p></li><li id="Aff7"><p class="c-article-author-affiliation__address">LIBPhys, Department of Physics, University of Coimbra, Coimbra, Portugal</p><p class="c-article-author-affiliation__authors-list">F. D. Amaro, J. M. R. Cardoso, J. A. M. Lopes, R. Peres, J. M. F. dos Santos & M. Silva</p></li><li id="Aff8"><p class="c-article-author-affiliation__address">New York University Abu Dhabi, Abu Dhabi, United Arab Emirates</p><p class="c-article-author-affiliation__authors-list">F. Arneodo, M. L. Benabderrahmane, G. Bruno, A. Di Giovanni & M. Messina</p></li><li id="Aff9"><p class="c-article-author-affiliation__address">Physik-Institut, University of Zurich, Zurich, Switzerland</p><p class="c-article-author-affiliation__authors-list">L. Baudis, A. Brown, C. Capelli, M. Galloway, S. Kazama, A. Kish, A. Manfredini, R. Peres, F. Piastra, S. Reichard & J. Wulf</p></li><li id="Aff10"><p class="c-article-author-affiliation__address">Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, USA</p><p class="c-article-author-affiliation__authors-list">T. Berger, E. Brown & K. Odgers</p></li><li id="Aff11"><p class="c-article-author-affiliation__address">Max-Planck-Institut für Kernphysik, Heidelberg, Germany</p><p class="c-article-author-affiliation__authors-list">S. Bruenner, D. Cichon, G. Eurin, C. Hasterok, F. Joerg, M. Lindner, T. Marrodán Undagoitia, V. Pizzella, N. Rupp, J. Schreiner, H. Simgen & O. Wack</p></li><li id="Aff12"><p class="c-article-author-affiliation__address">Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot, Israel</p><p class="c-article-author-affiliation__authors-list">R. Budnik, R. Itay, G. Koltman, H. Landsman, L. Levinson, A. Manfredini, N. Priel & H. Qiu</p></li><li id="Aff13"><p class="c-article-author-affiliation__address">Physikalisches Institut, Universität Freiburg, Freiburg, Germany</p><p class="c-article-author-affiliation__authors-list">D. Coderre, A. Elykov, B. Kaminsky, S. Lindemann, D. Ramírez García, A. Rocchetti, N. Šarčević, M. Schumann & F. Toschi</p></li><li id="Aff14"><p class="c-article-author-affiliation__address">SUBATECH, IMT Atlantique, CNRS/IN2P3, Université de Nantes, Nantes, France</p><p class="c-article-author-affiliation__authors-list">J. P. Cussonneau, S. Diglio, J. Masbou, K. Micheneau, C. Therreau & D. Thers</p></li><li id="Aff15"><p class="c-article-author-affiliation__address">Department of Physics, University of California, San Diego, CA, USA</p><p class="c-article-author-affiliation__authors-list">J. Fei, F. Lombardi, K. Ni, Y. Wei & J. Ye</p></li><li id="Aff16"><p class="c-article-author-affiliation__address">INFN-Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, L’Aquila, Italy</p><p class="c-article-author-affiliation__authors-list">W. Fulgione, A. Gallo Rosso, A. Molinario, J. Naganoma, R. Podviianiuk & Z. Wang</p></li><li id="Aff17"><p class="c-article-author-affiliation__address">INFN-Torino and Osservatorio Astrofisico di Torino, Torino, Italy</p><p class="c-article-author-affiliation__authors-list">W. Fulgione & G. Trinchero</p></li><li id="Aff18"><p class="c-article-author-affiliation__address">Department of Physics & Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL, USA</p><p class="c-article-author-affiliation__authors-list">L. Grandi, K. Miller, J. Pienaar, B. Riedel, E. Shockley, C. Tunnell & N. Upole</p></li><li id="Aff19"><p class="c-article-author-affiliation__address">Department of Physics ‘Ettore Pancini’, University of Napoli and INFN-Napoli, Naples, Italy</p><p class="c-article-author-affiliation__authors-list">M. Iacovacci, F. Marignetti & S. Mastroianni</p></li><li id="Aff20"><p class="c-article-author-affiliation__address">Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA</p><p class="c-article-author-affiliation__authors-list">A. Kopec, R. F. Lang & D. Masson</p></li><li id="Aff21"><p class="c-article-author-affiliation__address">LPNHE, Sorbonne Université, Université Paris Diderot, CNRS/IN2P3, Paris, France</p><p class="c-article-author-affiliation__authors-list">E. López Fune, L. Scotto Lavina & J. P. Zopounidis</p></li><li id="Aff22"><p class="c-article-author-affiliation__address">LAL, Université Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, Orsay, France</p><p class="c-article-author-affiliation__authors-list">C. Macolino</p></li><li id="Aff23"><p class="c-article-author-affiliation__address">Department of Physics and Astronomy, Rice University, Houston, TX, USA</p><p class="c-article-author-affiliation__authors-list">J. Naganoma, P. Shagin & C. Tunnell</p></li><li id="Aff24"><p class="c-article-author-affiliation__address">Physics and Astronomy Department, University of California, Los Angeles, CA, USA</p><p class="c-article-author-affiliation__authors-list">H. Wang</p></li></ol><h3 class="c-article__sub-heading" id="groups">Consortia</h3><div class="c-article-author-institutional-author" id="group-1"><h3 class="c-article-author-institutional-author__name u-h3">XENON Collaboration*</h3><ul class="c-article-author-institutional-author__author-list"><li class="c-article-author-institutional-author__author-name">E. Aprile</li><li class="c-article-author-institutional-author__author-name">, J. Aalbers</li><li class="c-article-author-institutional-author__author-name">, F. Agostini</li><li class="c-article-author-institutional-author__author-name">, M. Alfonsi</li><li class="c-article-author-institutional-author__author-name">, L. Althueser</li><li class="c-article-author-institutional-author__author-name">, F. D. Amaro</li><li class="c-article-author-institutional-author__author-name">, M. Anthony</li><li class="c-article-author-institutional-author__author-name">, V. C. Antochi</li><li class="c-article-author-institutional-author__author-name">, F. Arneodo</li><li class="c-article-author-institutional-author__author-name">, L. Baudis</li><li class="c-article-author-institutional-author__author-name">, B. Bauermeister</li><li class="c-article-author-institutional-author__author-name">, M. L. Benabderrahmane</li><li class="c-article-author-institutional-author__author-name">, T. Berger</li><li class="c-article-author-institutional-author__author-name">, P. A. Breur</li><li class="c-article-author-institutional-author__author-name">, A. Brown</li><li class="c-article-author-institutional-author__author-name">, A. Brown</li><li class="c-article-author-institutional-author__author-name">, E. Brown</li><li class="c-article-author-institutional-author__author-name">, S. Bruenner</li><li class="c-article-author-institutional-author__author-name">, G. Bruno</li><li class="c-article-author-institutional-author__author-name">, R. Budnik</li><li class="c-article-author-institutional-author__author-name">, C. Capelli</li><li class="c-article-author-institutional-author__author-name">, J. M. R. Cardoso</li><li class="c-article-author-institutional-author__author-name">, D. Cichon</li><li class="c-article-author-institutional-author__author-name">, D. Coderre</li><li class="c-article-author-institutional-author__author-name">, A. P. Colijn</li><li class="c-article-author-institutional-author__author-name">, J. Conrad</li><li class="c-article-author-institutional-author__author-name">, J. P. Cussonneau</li><li class="c-article-author-institutional-author__author-name">, M. P. Decowski</li><li class="c-article-author-institutional-author__author-name">, P. de Perio</li><li class="c-article-author-institutional-author__author-name">, P. 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Schindler</li><li class="c-article-author-institutional-author__author-name">, J. Schreiner</li><li class="c-article-author-institutional-author__author-name">, D. Schulte</li><li class="c-article-author-institutional-author__author-name">, M. Schumann</li><li class="c-article-author-institutional-author__author-name">, L. Scotto Lavina</li><li class="c-article-author-institutional-author__author-name">, M. Selvi</li><li class="c-article-author-institutional-author__author-name">, P. Shagin</li><li class="c-article-author-institutional-author__author-name">, E. Shockley</li><li class="c-article-author-institutional-author__author-name">, M. Silva</li><li class="c-article-author-institutional-author__author-name">, H. Simgen</li><li class="c-article-author-institutional-author__author-name">, C. Therreau</li><li class="c-article-author-institutional-author__author-name">, D. Thers</li><li class="c-article-author-institutional-author__author-name">, F. Toschi</li><li class="c-article-author-institutional-author__author-name">, G. Trinchero</li><li class="c-article-author-institutional-author__author-name">, C. Tunnell</li><li class="c-article-author-institutional-author__author-name">, N. Upole</li><li class="c-article-author-institutional-author__author-name">, M. Vargas</li><li class="c-article-author-institutional-author__author-name">, O. Wack</li><li class="c-article-author-institutional-author__author-name">, H. Wang</li><li class="c-article-author-institutional-author__author-name">, Z. Wang</li><li class="c-article-author-institutional-author__author-name">, Y. Wei</li><li class="c-article-author-institutional-author__author-name">, C. Weinheimer</li><li class="c-article-author-institutional-author__author-name">, D. Wenz</li><li class="c-article-author-institutional-author__author-name">, C. Wittweg</li><li class="c-article-author-institutional-author__author-name">, J. Wulf</li><li class="c-article-author-institutional-author__author-name">, J. Ye</li><li class="c-article-author-institutional-author__author-name">, Y. Zhang</li><li class="c-article-author-institutional-author__author-name">, T. Zhu</li><li class="c-article-author-institutional-author__author-name"> & J. P. Zopounidis</li></ul></div><h3 class="c-article__sub-heading" id="contributions">Contributions</h3><p>The XENON1T detector was designed and constructed by the XENON Collaboration. Operation, data processing, calibration, Monte Carlo simulations of the detector and of theoretical models, and data analyses were performed by a large number of XENON Collaboration members, who also discussed and approved the scientific results. The paper was written by A.F. and C. Wittweg. It was reviewed and edited by the collaboration and all authors approved the final version of the manuscript.</p><h3 class="c-article__sub-heading" id="corresponding-author">Corresponding authors</h3><p id="corresponding-author-list">Correspondence to <a id="corresp-c1" href="mailto:a.fieguth@uni-muenster.de">A. Fieguth</a> or <a id="corresp-c2" href="mailto:c.wittweg@uni-muenster.de">C. Wittweg</a>.</p></div></div></section><section data-title="Ethics declarations"><div class="c-article-section" id="ethics-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="ethics">Ethics declarations</h2><div class="c-article-section__content" id="ethics-content"> <h3 class="c-article__sub-heading" id="FPar5">Competing interests</h3> <p>The authors declare no competing interests.</p> </div></div></section><section data-title="Additional information"><div class="c-article-section" id="additional-information-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="additional-information">Additional information</h2><div class="c-article-section__content" id="additional-information-content"><p><b>Publisher’s note:</b> Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.</p></div></div></section><section data-title="Extended data figures and tables"><div class="c-article-section" id="Sec8-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="Sec8">Extended data figures and tables</h2><div class="c-article-section__content" id="Sec8-content"><div data-test="supplementary-info"><div id="figshareContainer" class="c-article-figshare-container" data-test="figshare-container"></div><div class="c-article-supplementary__item js-c-reading-companion-figures-item" data-test="supp-item" id="Fig5"><h3 class="c-article-supplementary__title u-h3"><a class="print-link" data-track="click" data-track-action="view supplementary info" data-test="supp-info-link" data-track-label="extended data fig. 1 spatial distribution of event" href="/articles/s41586-019-1124-4/figures/5" data-supp-info-image="//media.springernature.com/lw685/springer-static/esm/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig5_ESM.jpg">Extended Data Fig. 1 Spatial distribution of events.</a></h3><div class="c-article-supplementary__description" data-component="thumbnail-container"><p>Interaction depth <i>Z</i> versus squared radius <i>R</i><sup>2</sup> for events with energies 80–140 keV. High-density areas correspond to the edges of the TPC, where most of external β and γ radiation is absorbed. The 1,502-kg fiducial volume is indicated by the solid red line. Further segmentation into an inner (1.0 t) and an outer (0.5 t) volume is marked by the black dashed line.</p></div></div><div class="c-article-supplementary__item js-c-reading-companion-figures-item" data-test="supp-item" id="Fig6"><h3 class="c-article-supplementary__title u-h3"><a class="print-link" data-track="click" data-track-action="view supplementary info" data-test="supp-info-link" data-track-label="extended data fig. 2 energy resolution." href="/articles/s41586-019-1124-4/figures/6" data-supp-info-image="//media.springernature.com/lw685/springer-static/esm/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig6_ESM.jpg">Extended Data Fig. 2 Energy resolution.</a></h3><div class="c-article-supplementary__description" data-component="thumbnail-container"><p>Ratio of the mean peak energy (<i>μ</i><sub>E</sub>) to the peak width (<i>σ</i><sub>E</sub>) for low-energy monoenergetic lines in selected LXe dark-matter experiments (LUX<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 38" title="Akerib, D. S. et al. Signal yields, energy resolution, and recombination fluctuations in liquid xenon. Phys. Rev. D 95, 012008 (2017)." href="/articles/s41586-019-1124-4#ref-CR38" id="ref-link-section-d96320826e6039">38</a></sup> and XENON100<sup><a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 39" title="Aprile, E. et al. The XENON100 dark matter experiment. Astropart. Phys. 35, 573–590 (2012)." href="/articles/s41586-019-1124-4#ref-CR39" id="ref-link-section-d96320826e6043">39</a></sup>) and in the 1.5-t fiducial mass of the XENON1T detector. The relative resolution is defined as the <i>σ</i><sub>E</sub>/<i>μ</i><sub>E</sub> ratio of the Gaussian lines and is fitted using a phenomenological function (solid blue line). For XENON1T the data points are <sup>83m</sup>Kr (41.5 keV), <sup>131m</sup>Xe (163.9 keV), <sup>129m</sup>Xe (236.2 keV), <sup>214</sup>Pb (351.9 keV) and <sup>208</sup>Tl (510.8 keV). Only statistical uncertainties are shown for XENON1T (smaller than the markers). The energy of the 2<i>ν</i>ECEC peak is indicated by the black dashed line.</p></div></div><div class="c-article-supplementary__item js-c-reading-companion-figures-item" data-test="supp-item" id="Fig7"><h3 class="c-article-supplementary__title u-h3"><a class="print-link" data-track="click" data-track-action="view supplementary info" data-test="supp-info-link" data-track-label="extended data fig. 3 125i time evolution." href="/articles/s41586-019-1124-4/figures/7" data-supp-info-image="//media.springernature.com/lw685/springer-static/esm/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig7_ESM.jpg">Extended Data Fig. 3 <sup>125</sup>I time evolution.</a></h3><div class="c-article-supplementary__description" data-component="thumbnail-container"><p>Fit of the <sup>125</sup>I model to data in a 2<i>σ</i> energy interval around the mean energy of the <sup>125</sup>I peak in 10-d bins with Poisson uncertainties. Periods with an increased <sup>125</sup>I decay rate are attributed to artificial activations from neutron calibrations, equipment tests and a dedicated activation study. The decrease of the rate to the background level corresponds to an effective iodine decay constant of <i>τ</i> = 9.1 d. The best fit is shown as a solid black line. The green (yellow) bands mark the 1<i>σ</i> (2<i>σ</i>) model uncertainties resulting from the Poisson uncertainties of the <sup>125</sup>Xe data underlying the model. The pink bands indicate the data selection for the 2<i>ν</i>ECEC search, where the decay rate has returned to the background level.</p></div></div><div class="c-article-supplementary__item js-c-reading-companion-figures-item" data-test="supp-item" id="Fig8"><h3 class="c-article-supplementary__title u-h3"><a class="print-link" data-track="click" data-track-action="view supplementary info" data-test="supp-info-link" data-track-label="extended data fig. 4 χ2 curve for the number of me" href="/articles/s41586-019-1124-4/figures/8" data-supp-info-image="//media.springernature.com/lw685/springer-static/esm/art%3A10.1038%2Fs41586-019-1124-4/MediaObjects/41586_2019_1124_Fig8_ESM.jpg">Extended Data Fig. 4 <i>χ</i><sup>2</sup> curve for the number of measured 2<i>ν</i>ECEC events.</a></h3><div class="c-article-supplementary__description" data-component="thumbnail-container"><p>By comparing the best-fit value of <i>N</i><sub>2<i>ν</i>ECEC</sub> = 126 events to a null result one obtains <span class="mathjax-tex">\(\sqrt{{\rm{\Delta }}{\chi }^{2}}=4.4\)</span>.</p></div></div><div class="c-article-supplementary__item" data-test="supp-item"><div class="c-article-table" data-test="inline-table" data-container-section="table" id="table-1"><figure><figcaption class="c-article-table__figcaption"><b id="Tab1" data-test="table-caption">Extended Data Table 1 Systematic uncertainties</b></figcaption><div class="u-text-right u-hide-print"><a class="c-article__pill-button" data-test="table-link" data-track="click" data-track-action="view table" data-track-label="button" rel="nofollow" href="/articles/s41586-019-1124-4/tables/1" aria-label="Full size table 1"><span>Full size table</span><svg width="16" height="16" focusable="false" role="img" aria-hidden="true" class="u-icon"><use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#icon-eds-i-chevron-right-small"></use></svg></a></div></figure></div></div></div></div></div></section><section data-title="Rights and permissions"><div class="c-article-section" id="rightslink-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="rightslink">Rights and permissions</h2><div class="c-article-section__content" id="rightslink-content"><p class="c-article-rights"><a data-track="click" data-track-action="view rights and permissions" data-track-label="link" href="https://s100.copyright.com/AppDispatchServlet?title=Observation%20of%20two-neutrino%20double%20electron%20capture%20in%20124Xe%20with%20XENON1T&author=E.%20Aprile%20et%20al&contentID=10.1038%2Fs41586-019-1124-4&copyright=The%20Author%28s%29%2C%20under%20exclusive%20licence%20to%20Springer%20Nature%20Limited&publication=0028-0836&publicationDate=2019-04-24&publisherName=SpringerNature&orderBeanReset=true">Reprints and permissions</a></p></div></div></section><section aria-labelledby="article-info" data-title="About this article"><div class="c-article-section" id="article-info-section"><h2 class="c-article-section__title js-section-title js-c-reading-companion-sections-item" id="article-info">About this article</h2><div class="c-article-section__content" id="article-info-content"><div class="c-bibliographic-information"><div class="u-hide-print c-bibliographic-information__column c-bibliographic-information__column--border"><a data-crossmark="10.1038/s41586-019-1124-4" target="_blank" rel="noopener" href="https://crossmark.crossref.org/dialog/?doi=10.1038/s41586-019-1124-4" data-track="click" data-track-action="Click Crossmark" data-track-label="link" data-test="crossmark"><img loading="lazy" width="57" height="81" alt="Check for updates. 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Observation of two-neutrino double electron capture in 124Xe with XENON1T | Nature