Abstract

$$^{180m}$$$$\mathrm{Ta}$$ 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 $$^{76}$$$$\mathrm{Ge}$$ using an array of high-purity germanium detectors, to search for the decay of $$^{180m}$$$$\mathrm{Ta}$$. Here, 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 $$^{180m}$$$$\mathrm{Ta}$$ half-life on the different decay channels. In conclusion, with new limits up to $$\mathrm{1.5 × 10^{19} yr}$$, 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 $$T_\frac{1}{2} < 0.29 × 10^{18}$$$$\mathrm{yr}$$.

Authors:

Arnquist, I. J. ^[1]; Avignone, F.  T.; Barabash, A.  S.; Barton, C.  J.; Bhimani, K.  H.; Blalock, E.; Bos, B.; Busch, M.; Buuck, M.; Caldwell, T.  S.; Christofferson, C.  D.; Chu, P. -H. ;

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Clark, M.  L.; Cuesta, C.; Detwiler, J.  A.; Efremenko, Yu; Ejiri, H.; Elliott, S.  R. ;

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Giovanetti, G.  K.; Goett, J.

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more »; Green, M.  P.; Gruszko, J.; Guinn, I.  S.; Guiseppe, V.  E.; Haufe, C.  R.; Henning, R.; Hervas Aguilar, D.; Hoppe, E.  W.; Hostiuc, A.; Kim, I.; Kouzes, R.  T.; Lannen V., T.  E.; Li, A.; López-Castaño, J.  M.; Massarczyk, R. ;

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Meijer, S. J. ;

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Meijer, W. ;

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Oli, T.  K.; Paudel, L.  S.; Pettus, W.; Poon, A.  W. P.; Radford, D.  C.; Reine, A.  L.; Rielage, K. ;

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Rouyer, A.; Ruof, N.  W.; Schaper, D. C. ;

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Schleich, S.  J.; Smith-Gandy, T.  A.; Tedeschi, D.; Thompson, J.  D.; Varner, R.  L.; Vasilyev, S.; Watkins, S. L. ;

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Wilkerson, J.  F.; Wiseman, C.; Xu, W.; Yu, C. -H.; Alves, D.  S. M.; Hebenstiel, L.; Ramani, H. « less

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+ Show Author Affiliations

1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Majorana Collaboration. et al.

Publication Date:

Wed Oct 11 00:00:00 EDT 2023

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); University of North Carolina, Chapel Hill, NC (United States)

Sponsoring Org.:

USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Nuclear Physics (NP); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); National Science Foundation (NSF)

Contributing Org.:

Majorana Collaboration

OSTI Identifier:

2202631

Alternate Identifier(s):

OSTI ID: 2294169

Report Number(s):

LA-UR-23-25687
Journal ID: ISSN 0031-9007

Grant/Contract Number:  

89233218CNA000001; AC02-05CH11231; AC05-00OR22725; AC05-76RL0130; FG02-97ER41020; FG02-97ER41033; FG02-97ER41041; SC0012612; SC0014445; SC0018060; SC0022339; LANLEM77/LANLEM78; MRI-0923142; PHY-1003399; PHY-1102292; PHY-1206314; PHY-1614611; PHY-1812409; PHY-1812356; PHY-2111140; PHY-2209530

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Letters

Additional Journal Information:

Journal Volume: 131; Journal Issue: 15; Journal ID: ISSN 0031-9007

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; alpha decay; beta decay; isomer decays; lifetimes & widths; nuclear astrophysics; nuclear decay; nuclear structure & decays; nuclear transition rates; 150 ≤ A ≤ 189; radiation detectors; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS