Measurement of the double-$$\varvec{\beta }$$ decay of $$\varvec{^{150}}$$Nd to the 0$$\varvec{^+_1}$$ excited state of $$\varvec{^{150}}$$Sm in NEMO-3

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2023-12, Vol.83 (12), Article 1117
• Main Authors: Aguerre, X., Arnold, R., Augier, C., Barabash, A. S., Basharina-Freshville, A., Blondel, S., Blot, S., Bongrand, M., Breier, R., Brudanin, V., Busto, J., Bystryakov, A., Caffrey, A. J., Cerna, C., Cesar, J. P., Ceschia, M., Chauveau, E., Chopra, A., Dawson, L., Duchesneau, D., Durand, D., Evans, J. J., Flack, R., Franchini, P., Garrido, X., Girard-Carillo, C., Guillon, B., Guzowski, P., Hoballah, M., Hodák, R., Hubert, P., Hussain, M. H., Jullian, S., Klimenko, A., Kochetov, O., Konovalov, S. I., Koňařík, F., Křižák, T., Lalanne, D., Lang, K., Lemière, Y., Li, P., Loaiza, P., Lutter, G., Macko, M., Mamedov, F., Marquet, C., Mauger, F., Minotti, A., Morgan, B., Nemchenok, I., Nomachi, M., Nowacki, F., Ohsumi, H., Oliviéro, G., Palušová, V., Patrick, C., Perrot, F., Petro, M., Pin, A., Piquemal, F., Povinec, P., Pratt, S., Přidal, P., Quinn, W. S., Ramachers, Y. A., Remoto, A., Reyss, J. L., Riddle, C. L., Rukhadze, E., Saakyan, R., Salamatin, A., Salazar, R., Sarazin, X., Sedgbeer, J., Shitov, Yu, Simard, L., Šimkovic, F., Smetana, A., Smolnikov, A., Söldner-Rembold, S., Štekl, I., Suhonen, J., Szklarz, G., Tedjditi, H., Thomas, J., Timkin, V., Tretyak, V. I., Umatov, V. I., Vanushin, I., Vereshchaka, Y., Vorobel, V., Waters, D., Xie, F.
• Format: Article
• Language: English
• ISSN: 1434-6052; 1434-6052
• DOI: 10.1140/epjc/s10052-023-12227-x

The NEMO-3 results for the double- $$\beta $$ β decay of $$^{150}$$ 150 Nd to the 0 $$^+_1$$ 1 + and 2 $$^+_1$$ 1 + excited states of $$^{150}$$ 150 Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope $$^{150}$$ 150 Nd are used in the analysis. The signal of the $$2\nu \beta \beta $$ 2 ν β β transition to the 0 $$^+_1$$ 1 + excited state is detected with a statistical significance exceeding 5 $$\sigma $$ σ . The half-life is measured to be $$T_{1/2}^{2\nu \beta \beta }(0^+_1) = \left[ 1.11 ^{+0.19}_{-0.14} \,\left( \hbox {stat}\right) ^{+0.17}_{-0.15}\,\left( \hbox {syst}\right) \right] \times 10^{20}$$ T 1 / 2 2 ν β β ( 0 1 + ) = 1 . 11 - 0.14 + 0.19 stat - 0.15 + 0.17 syst × 10 20  year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the $$2\nu \beta \beta $$ 2 ν β β decay to the 2 $$^+_1$$ 1 + level the limit is $$T^{2\nu \beta \beta }_{1/2}(2^+_1) > 2.42 \times 10^{20}~\hbox {year}$$ T 1 / 2 2 ν β β ( 2 1 + ) > 2.42 × 10 20 year . The limits on the $$0\nu \beta \beta $$ 0 ν β β decay to the 0 $$^+_1$$ 1 + and 2 $$^+_1$$ 1 + levels of $$^{150}$$ 150 Sm are significantly improved to $$T_{1/2}^{0\nu \beta \beta }(0^+_1) > 1.36 \times 10^{22}~\hbox {year}$$ T 1 / 2 0 ν β β ( 0 1 + ) > 1.36 × 10 22 year and $$T_{1/2}^{0\nu \beta \beta }(2^+_1) > 1.26 \times 10^{22}~\hbox {year}$$ T 1 / 2 0 ν β β ( 2 1 + ) > 1.26 × 10 22 year .