1. Double-beta decay of $^{150}$Nd to excited levels of $^{150}$Sm
- Author
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Barabash, A. S., Belli, P., Bernabei, R., Boiko, R. S., Cappella, F., Caracciolo, V., Cerulli, R., Danevich, F. A., Fang, D. L., Ferella, F., Incicchitti, A., Kobychev, V. V., Konovalov, S. I., Laubenstein, M., Leoncini, A., Merlo, V., Nisi, S., Nitescu, O., Poda, D. V., Polischuk, O. G., Shcherbakov, I. B. -K., Simkovic, F., Timonina, A., Tinkova, V. S., Tretyak, V. I., and Umatov, V. I.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
The $2\nu2\beta$ decay of $^{150}$Nd to the first excited 740.5 keV $0^{+}_{1}$ level of $^{150}$Sm was measured over 5.845 yr with the help of a four-crystal low-background HPGe $\gamma$ spectrometry system in the underground low-background laboratory STELLA of LNGS-INFN. A 2.381 kg highly purified Nd-containing sample was employed as the decay source. The expected de-excitation gamma-quanta of the $0^{+}_{1}$ level with energies 334.0 keV and 406.5 keV were observed both in one-dimensional spectrum and in coincidence data resulting in the half-life $T_{1/2}=[0.83^{+0.18}_{-0.13}\mathrm{(stat)}^{+0.16}_{-0.19}\mathrm{(syst)}]\times 10^{20}$ yr. Interpreting an excess of the 334.0-keV peak area as an indication of the $2\beta$ decay of $^{150}$Nd to the 334.0 keV $2^+_1$ excited level of $^{150}$Sm with a half-life of $T_{1/2}=[1.5^{+2.3}_{-0.6}\mathrm{(stat)}\pm 0.4\mathrm{(syst)}]\times10^{20}$ yr, the $2\nu2\beta$ half-life of $^{150}$Nd for the transition to the 0$^{+}_{1}$ level is $T_{1/2}=[1.03^{+0.35}_{-0.22}\mathrm{(stat)}^{+0.16}_{-0.19}\mathrm{(syst)}]\times 10^{20}$ yr, in agreement with the previous experiments. Both half-life values reasonably agree with the theoretical calculations in the framework of proton-neutron QRPA with isospin restoration combined with like nucleon QRPA for description of excited states in the final nuclei. For $2\nu2\beta$ and $0\nu2\beta$ transitions of $^{150}$Nd and $^{148}$Nd to several excited levels of $^{150}$Sm and $^{148}$Sm, limits were set at level of $T_{1/2}>10^{20}-10^{21}$ yr., Comment: 61 pages, 19 figures, 14 tables
- Published
- 2025