Search for the double-beta decay of 82Se to the excited states of 82Kr with NEMO-3

Arnold, R.; Augier, C.; Barabash, A. S.; Basharina-Freshville, A.; Blondel, S.; Blot, S.; Bongrand, M.; Boursette, D.; Breier, R.; Brudanin, V.; Busto, J.; Caffrey, A. J.; Calvez, S.; Cascella, M.; Cerna, C.; Cesar, J. P.; Chapon, A.; Chauveau, E.; Chopra, A.; Dawson, L.; Duchesneau, D.; Durand, D.; Egorov, V.; Eurin, G.; Evans, J. J.; Fajt, L.; Filosofov, D.; Flack, R.; Garrido, X.; Girard-Carillo, C.; Gomez, H.; Guillon, B.; Guzowski, P.; Hodak, R.; Huber, A.; Hubert, P.; Hugon, C.; Jullian, S.; Klimenko, A.; Kochetov, O.; Konovalov, S. I.; Kovalenko, V.; Lalanne, D.; Lang, K.; Lemiere, Y.; Le Noblet, T.; Liptak, Z.; Liu, X. R.; Loaiza, P.; Lutter, G.; Macko, M.; Macolino, C.; Mamedov, F.; Marquet, C.; Mauger, F.; Minotti, A.; Morgan, B.; Mott, J.; Nemchenok, I.; Nomachi, M.; Nova, F.; Nowacki, F.; Ohsumi, H.; Oliviero, G.; Pahlka, R. B.; Palusova, V.; Patrick, C.; Perrot, F.; Pin, A.; Piquemal, F.; Povinec, P.; Pridal, P.; Ramachers, Y. A.; Remoto, A.; Reyss, J. L.; Richards, B.; Riddle, C. L.; Rukhadze, E.; Saakyan, R.; Salazar, R.; Sarazin, X.; Sedgbeer, J.; Shitov, Y.; Simard, L.; Simkovic, F.; Smetana, A.; Smolek, K.; Smolnikov, A.; Soldner-Rembold, S.; Soule, B.; Stekl, I.; Suhonen, J.; Sutton, C. S.; Szklarz, G.; Tedjditi, H.; Thomas, J.; Timkin, V.; Torre, S.; Tretyak, V. I.; Tretyak, V. I.; Umatov, V. I.; Vanushin, I.; Vilela, C.; Vorobel, V.; Waters, D.; Xie, F.; Zukauskas, A.

doi:10.1016/j.nuclphysa.2020.121701

The double-beta decay of 82Se to the 01+ excited state of 82Kr has been studied with the NEMO-3 detector using 0.93 kg of enriched 82Se measured for 4.75 y, corresponding to an exposure of 4.42 kg⋅y. A dedicated analysis to reconstruct the γ-rays has been performed to search for events in the 2e2γ channel. No evidence of a 2νββ decay to the 01+ state has been observed and a limit of T1/22ν(Se82,0gs+→01+)>1.3×1021y at 90% CL has been set. Concerning the 0νββ decay to the 01+ state, a limit for this decay has been obtained with T1/20ν(Se82,0gs+→01+)>2.3×1022y at 90% CL, independently from the 2νββ decay process. These results are obtained for the first time with a tracko-calo detector, reconstructing every particle in the final state.