Journal Article

An improved limit on the neutrinoless double-electron capture of  $$^{36}$$ Ar with GERDA

Chernogorov, A., Jochum, J., Gangapshev, A., Kuzminov, V. V., Garfagnini, A., Csáthy, J. Janicskó, Majorovits, B., Misiaszek, M., Shirchenko, M., Bettini, A., Hakenmüller, J., Kneißl, R., Korošec, M., Nemchenok, I., Araujo, G. R., Rumyantseva, N., Shtembari, L., Zatschler, B., Selivanenko, O., Müller, Y., Schwingenheuer, B., Stukov, D., Agostini, M., D’Andrea, V., Krause, P., Doroshkevich, E., Smolnikov, A., Zhukov, S. V., Lippi, I., Bothe, V., Vasenko, A. A., Veresnikova, A., Kilgus, K., Gurentsov, V., Biancacci, V., Zhitnikov, I., Kirpichnikov, I. V., Sturm, K. von, Schönert, S., Brudanin, V., Zschocke, A., Klimenko, A., Fischer, F., Lubsandorzhiev, B., Maneschg, W., Pelczar, K., Riboldi, S., Shevchik, E., Schulz, O., Gusev, K., Caldwell, A., Marshall, G., Bossio, E., Kochetov, O., Huang, J., Balata, M., Khushbakht, H., Fomina, M., Kermaïdic, Y., Wojcik, M., Bauer, C., Knöpfle, K. T., Morella, M., Vignoli, C., Bezrukov, L., Bakalyarov, A. M., Salamida, F., Piseri, P., Barabanov, I., Redchuk, M., Schreiner, J., Lindner, M., Pandola, L., Macolino, C., Kihm, T., Yanovich, E., Wester, T., Kornoukhov, V. N., Comellato, T., Manzanillas, L., Zuzel

2024

Overview

The GERmanium Detector Array ( Gerda ) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of$$^{36}$$36 Ar, a candidate isotope for the two-neutrino double-electron capture (2$$\\nu $$ν ECEC) and therefore for the neutrinoless double-electron capture (0$$\\nu $$ν ECEC). If detected, this process would give evidence of lepton number violation and the Majorana nature of neutrinos. In the radiative 0$$\\nu $$ν ECEC of$$^{36}$$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$$^{36}$$36 Ar 0$$\\nu $$ν 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$$T_{1/2} >1.5\\cdot 10^{22} $$T 1 / 2 > 1.5 · 10 22  year.

• Publisher: Springer
• Subject: Detectors / Electrons