Search for two-neutrino double electron capture on ${}^{124}$Xe with the XMASS-I detector

Abstract

Double electron capture is a rare nuclear decay process in which two orbital electrons are captured simultaneously in the same nucleus. Measurement of its two-neutrino mode would provide a new reference for the calculation of nuclear matrix elements whereas observation of its neutrinoless mode would demonstrate lepton number violation. A search for two-neutrino double electron capture on ${}^{124}$Xe is performed using 165.9 days of data collected with the XMASS-I liquid xenon detector. No significant excess above background was observed and we set a lower limit on the half-life as $4.7\times 10^{21}$ years at 90% confidence level. The obtained limit has ruled out parts of some theoretical expectations. We obtain a lower limit on the ${}^{126}$Xe two-neutrino double electron capture half-life of $4.3\times 10^{21}$ years at 90% confidence level as well.

6 pages, 3 figures, accepted for publication in Physics Letters B

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Cited by in corpus (7)

• Two-neutrino double electron capture on ${}^{124}$Xe based on an effective theory and the nuclear shell model
• Improved search for two-neutrino double electron capture on ${}^{124}$Xe and ${}^{126}$Xe using particle identification in XMASS-I
• Search for Two-Neutrino Double Electron Capture of ${}^{124}$Xe with XENON100
• A measurement of the time profile of scintillation induced by low energy gamma-rays in liquid xenon with the XMASS-I detector
• Search for solar Kaluza-Klein axion by annual modulation with the XMASS-I detector
• Direct dark matter searches with the full data set of XMASS-I
• Large-scale shell-model investigation of $2\nu$ECEC in ${}^{132}$Ba and ${}^{78}$Kr