학술논문
Constraints on the Decay of Ta180m
Document Type
article
Author
Arnquist, IJ; Avignone, FT; Barabash, AS; Barton, CJ; Bhimani, KH; Blalock, E; Bos, B; Busch, M; Buuck, M; Caldwell, TS; Christofferson, CD; Chu, P-H; Clark, ML; Cuesta, C; Detwiler, JA; Efremenko, Yu; Ejiri, H; Elliott, SR; Giovanetti, GK; Goett, J; Green, MP; Gruszko, J; Guinn, IS; Guiseppe, VE; Haufe, CR; Henning, R; Aguilar, D Hervas; Hoppe, EW; Hostiuc, A; Kim, I; Kouzes, RT; V., TE Lannen; Li, A; López-Castaño, JM; Massarczyk, R; Meijer, SJ; Meijer, W; Oli, TK; Paudel, LS; Pettus, W; Poon, AWP; Radford, DC; Reine, AL; Rielage, K; Rouyer, A; Ruof, NW; Schaper, DC; Schleich, SJ; Smith-Gandy, TA; Tedeschi, D; Thompson, JD; Varner, RL; Vasilyev, S; Watkins, SL; Wilkerson, JF; Wiseman, C; Xu, W; Yu, C-H; Alves, DSM; Hebenstiel, L; Ramani, H
Source
Physical Review Letters. 131(15)
Subject
Language
Abstract
^{180m}Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known β and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower-energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter, and K-spin violation. For this study, we repurposed the Majorana Demonstrator, an experimental search for the neutrinoless double-beta decay of ^{76}Ge using an array of high-purity germanium detectors, to search for the decay of ^{180m}Ta. More than 17 kg, the largest amount of tantalum metal ever used for such a search, was installed within the ultralow-background detector array. In this Letter, we present results from the first year of Ta data taking and provide an updated limit for the ^{180m}Ta half-life on the different decay channels. With new limits up to 1.5×10^{19} yr, we improved existing limits by 1-2 orders of magnitude which are the most sensitive searches for a single β and electron capture decay ever achieved. Over all channels, the decay can be excluded for T_{1/2}