We investigate the possibilities of observing the decay mode for 124Xe in which two electrons are captured, two neutrinos are emitted, and the final daughter nucleus is in its ground state, using dark matter experiments with liquid xenon. The first upper limit of the decay half-life is calculated to be 1.66×1021 years at a 90% confidence level (C.L.) obtained with the published background data from the XENON100 experiment. Employing a known background model from the Large Underground Xenon (LUX) experiment, we predict that the detection of double-electron capture of 124Xe to the ground state of 124Te with LUX will have approximately 115 events, assuming a half-life of 2.9 × 1021 years. We conclude that measuring 124Xe 2ν double-electron capture to the ground state of 124Te can be performed more precisely with the proposed LUX-Zeplin (LZ) experiment.
@article{arxiv.1310.1946,
title = {Measuring Double-Electron Capture with Liquid Xenon Experiments},
author = {D. -M. Mei and I. Marshall and W. -Z. Wei and C. Zhang},
journal= {arXiv preprint arXiv:1310.1946},
year = {2015}
}