Journal Article

Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of 76Ge to Excited States of 76Se

Pettus, W., Busch, M., Chan, Y-D., Buuck, M., Edwins, D. W., Elliott, S.R., Oli, T.K., Poon, A.W.P., Kim, I., Chu, P-H., Meijer, S.J., Zhu, B.X., Hegedus, R.J., Detwiler, J.A., Kidd, M.F., Efremenko, Yu, Rager, J., Barton, C. J., Tedeschi, D., Rielage, K., Hoppe, E.W., Christofferson, C.D., Avignone, F.T., Martin, R.D., Myslik, J., Stortini, M.J., Bertrand, F.E., Clark, M.L., Reine, A.L., Wiseman, C., Cuesta, C., Martin, E. L., Ejiri, H., Hervas Aguilar, D., Green, M.P., Lopez, A.M., Barabash, A.S., Yu, C.-H., Radford, D.C., Arnquist, I.J., Gruszko, J., Ruof, N.W., López-Castaño, J.M., Othman, G., Kouzes, R.T., Haufe, C.R., Mertens, S., Xu, W., Bos, B., Gilliss, T., Varner, R.L., Guiseppe, V.E., Drobizhev, A., Henning, R., Massarczyk, R., Wilkerson, J.F., Caldwell, T.S., Guinn, I.S., Giovanetti, G.K., Hostiuc, A.

2020

Overview

The MAJORANA DEMONSTRATOR is searching for double-beta decay of 76Ge to excited states (E.S.) in 76Se using a modular array of high purity Germanium detectors. 76Ge can decay into three E.S.s of 76Se. The E.S. decays have a clear event signature consisting of a ββ-decay with the prompt emission of one or two γ-rays, resulting in with high probability in a multi-site event. The granularity of the DEMONSTRATOR detector array enables powerful discrimination of this event signature from backgrounds. Using 21.3 kg-y of isotopic exposure, the DEMONSTRATOR has set world leading limits for each E.S. decay, with 90% CL lower half-life limits in the range of (0.56 ‒ 2.1) ⋅ 1024 y. In particular, for the 2v transition to the first 0+ E.S. of 76Se, a lower half-life limit of 0.68 ⋅ 1024 at 90% CL was achieved.

• Publisher: IOP Publishing
• Subject: Arrays / Beta decay / Excitation / Gamma rays / Germanium / Half-life / NUCLEAR PHYSICS AND RADIATION PHYSICS / Physics