PT Journal
AU NEXT Collaboration (Martinez-Lema, Gea
   Benlloch-Rodriguez, JM
   Carcel, S
   Carrion, JV
   Diaz, J
   Felkai, R
   Kekic, M
   Lopez-March, N
   Martin-Albo, J
   Martinez, A
   Martinez-Vara, M
   Muñoz Vidal, J
   Novella, P
   Palmeiro, B
   Querol, M
   Renner, J
   Romo-Luque, C
   Sorel, M
   Uson, A
   Yahlali, N
TI Sensitivity of the NEXT experiment to Xe-124 double electron capture
SO Journal of High Energy Physics
JI J. High Energy Phys.
PY 2021
BP 203
EP 25pp
VL 02
IS 2
DI 10.1007/JHEP02(2021)203
LA English
DE Dark Matter and Double Beta Decay (experiments)
AB Double electron capture by proton-rich nuclei is a second-order nuclear process analogous to double beta decay. Despite their similarities, the decay signature is quite different, potentially providing a new channel to measure the hypothesized neutrinoless mode of these decays. The Standard-Model-allowed two-neutrino double electron capture (2 nu EC EC) has been predicted for a number of isotopes, but only observed in Kr-78, Ba-130 and, recently, Xe-124. The sensitivity to this decay establishes a benchmark for the ultimate experimental goal, namely the potential to discover also the lepton-number-violating neutrinoless version of this process, 0 nu EC EC. Here we report on the current sensitivity of the NEXT-White detector to Xe-124 2 nu EC EC and on the extrapolation to NEXT-100. Using simulated data for the 2 nu EC EC signal and real data from NEXT-White operated with Xe-124-depleted gas as background, we define an optimal event selection that maximizes the NEXT-White sensitivity. We estimate that, for NEXT-100 operated with xenon gas isotopically enriched with 1 kg of Xe-124 and for a 5-year run, a sensitivity to the 2 nu EC EC half-life of 6 x 10(22) y (at 90% confidence level) or better can be reached.
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