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Physics in the MeV range with PandaX-4T: measurement of double beta decay half-life of Xe-136

PandaX-4T is not just a dark matter detector, as you may be more familiar with. For such a large and exquisite detector, we can explore multiple physics topics. Neutrino physics is one such important direction.

Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double-beta decay. We report the measurement of DBD half-life of Xe-136 using the PandaX-4T. With 3.7-tonne natural xenon, we have accumulated a large number of DBD events in the first 94.9-day commissioning data. With a Xe-136 exposure of 15.5 kg-year, we establish the half-life as 2.27 ± 0.03(stat.) ± 0.09(syst.) × 1021 year.

The precision of our measurement can be comparable with those from dedicated DBD experiments. This is the first DBD half-life measurement with natural xenon and demonstrates the physics capability of a large-scale liquid xenon TPC in the field of rare event searches. For more information, please find it here.