An improved limit on the neutrinoless double-electron capture of
36Ar with GERDA.
THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2024;
84:34. [PMID:
38229675 PMCID:
PMC10788323 DOI:
10.1140/epjc/s10052-023-12280-6]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 11/21/2023] [Indexed: 01/18/2024]
Abstract
The GERmanium Detector Array (Gerda) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of 36 Ar, a candidate isotope for the two-neutrino double-electron capture (2ν ECEC) and therefore for the neutrinoless double-electron capture (0ν ECEC). If detected, this process would give evidence of lepton number violation and the Majorana nature of neutrinos. In the radiative 0ν ECEC of 36 Ar, a monochromatic photon is emitted with an energy of 429.88 keV, which may be detected by the Gerda germanium detectors. We searched for the 36 Ar 0ν ECEC with Gerda data, with a total live time of 4.34 year (3.08 year accumulated during Gerda Phase II and 1.26 year during Gerda Phase I). No signal was found and a 90% CL lower limit on the half-life of this process was established T 1 / 2 > 1.5 · 10 22 year.
Supplementary Information
The online version contains supplementary material available at 10.1140/epjc/s10052-023-12280-6.
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