Double-beta decay of to excited levels of

A. S. Barabash; P. Belli; R. Bernabei; R. S. Boiko; F. Cappella; V. Caracciolo; R. Cerulli; F. A. Danevich; D. L. Fang; F. Ferella; A. Incicchitti; V. V. Kobychev; S. I. Konovalov; M. Laubenstein; A. Leoncini; V. Merlo; S. Nisi; O. Niţescu; D. V. Poda; O. G. Polischuk; I. B.-K. Shcherbakov; F. Šimkovic; A. Timonina; V. S. Tinkova; V. I. Tretyak; V. I. Umatov

doi:10.1140/epjc/s10052-025-13901-y

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2025) 85: 174
https://doi.org/10.1140/epjc/s10052-025-13901-y

Regular Article - Experimental Physics

Double-beta decay of $^{150} Nd$ $^{150}\hbox {Nd}$ to excited levels of $^{150} Sm$ $^{150}\hbox {Sm}$

A. S. Barabash¹, P. Belli²^,3, R. Bernabei²^,3^a, R. S. Boiko⁴^,5, F. Cappella⁶^,7, V. Caracciolo²^,3, R. Cerulli²^,3, F. A. Danevich²^,4, D. L. Fang⁸^,9, F. Ferella¹⁰, A. Incicchitti⁶^,7, V. V. Kobychev⁴, S. I. Konovalov¹, M. Laubenstein¹⁰, A. Leoncini²^,3, V. Merlo²^,3, S. Nisi¹⁰, O. Niţescu¹¹^,12^,13, D. V. Poda¹⁴, O. G. Polischuk⁴^,6, I. B.-K. Shcherbakov¹⁵, F. Šimkovic¹¹^,16, A. Timonina¹⁵, V. S. Tinkova¹⁷^,18^,18, V. I. Tretyak⁴^,10 and V. I. Umatov¹

¹ Affiliated with an Institute Taking Part in the Experiment Described in this Article, Kyiv, Ukraine
² INFN sezione Roma “Tor Vergata”, 00133, Rome, Italy
³ Dipartimento di Fisica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
⁴ Institute for Nuclear Research of NASU, 03028, Kyiv, Ukraine
⁵ National University of Life and Environmental Sciences of Ukraine, 03041, Kyiv, Ukraine
⁶ INFN sezione Roma, 00185, Rome, Italy
⁷ Dipartimento di Fisica, Università di Roma “La Sapienza”, 00185, Rome, Italy
⁸ Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
⁹ University of Chinese Academy of Sciences, 100049, Beijing, China
¹⁰ INFN Laboratori Nazionali del Gran Sasso, 67100, Assergi, AQ, Italy
¹¹ Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, 842 48, Bratislava, Slovakia
¹² International Centre for Advanced Training and Research in Physics, P.O. Box MG12, 077125, Magurele, Romania
¹³ “Horia Hulubei” National Institute of Physics and Nuclear Engineering, 30 Reactorului, POB MG-6, 077125, Bucharest-Măgurele, Romania
¹⁴ Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405, Orsay, France
¹⁵ State Scientific Institution “Institute for Single Crystals” of NASU, 61072, Kharkiv, Ukraine
¹⁶ Institute of Experimental and Applied Physics, Czech Technical University in Prague, 110 00, Prague, Czech Republic
¹⁷ Institute for Scintillation Materials of NASU, 61072, Kharkiv, Ukraine
¹⁸ Present affiliation: Research Centre UNIZA, University of Žilina, Univerzitná 8215/1, 010 26, Žilina, Slovakia

^a rita.bernabei@roma2.infn.it

Received: 20 May 2024
Accepted: 3 February 2025
Published online: 11 February 2025

Abstract

The $2 ν 2 β$ $2\nu 2\beta$ decay of $^{150} Nd$ $^{150}\hbox {Nd}$ to the first excited 740.5 keV $0_{1}^{+}$ $0^{+}_{1}$ level of $^{150} Sm$ $^{150}\hbox {Sm}$ was measured over 5.845 years with the help of a four-crystal low-background HPGe $γ$ $\gamma$ 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 $0_{1}^{+}$ $0^{+}_{1}$ 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 $T_{1 / 2} = [0 . 83_{- 0.13}^{+ 0.18} {(stat)}_{- 0.19}^{+ 0.16} (syst)] \times 10^{20}$ $T_{1/2}=[0.83^{+0.18}_{-0.13}\mathrm {(stat)}^{+0.16}_{-0.19}\mathrm {(syst)}]\times 10^{20}$ year. Interpreting an excess of the 334.0-keV peak area as an indication of the $2 β$ $2\beta$ decay of $^{150} Nd$ $^{150}\hbox {Nd}$ to the 334.0 keV $2_{1}^{+}$ $$2^+_1$$ excited level of $^{150} Sm$ $^{150}\hbox {Sm}$ with a half-life of $T_{1 / 2} = [1 . 5_{- 0.6}^{+ 2.3} (stat) \pm 0.4 (syst)] \times 10^{20}$ $T_{1/2}=[1.5^{+2.3}_{-0.6}\mathrm {(stat)}\pm 0.4\mathrm {(syst)}]\times 10^{20}$ year, the $2 ν 2 β$ $2\nu 2\beta$ half-life of $^{150} Nd$ $^{150}\hbox {Nd}$ for the transition to the 0 $_{1}^{+}$ $^{+}_{1}$ level is $T_{1 / 2} = [1 . 03_{- 0.22}^{+ 0.35} {(stat)}_{- 0.19}^{+ 0.16} (syst)] \times 10^{20}$ $T_{1/2}=[1.03^{+0.35}_{-0.22}\mathrm {(stat)}^{+0.16}_{-0.19}\mathrm {(syst)}]\times 10^{20}$ year, 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 $2 ν 2 β$ $2\nu 2\beta$ and $0 ν 2 β$ $0\nu 2\beta$ transitions of $^{150} Nd$ $^{150}\hbox {Nd}$ and $^{148} Nd$ $^{148}\hbox {Nd}$ to several excited levels of $^{150} Sm$ $^{150}\hbox {Sm}$ and $^{148} Sm$ $^{148}\hbox {Sm}$ , limits were set at level of $T_{1 / 2} > 10^{20} - 10^{21}$ $T_{1/2}>10^{20}-10^{21}$ year.

Present address: Present affiliation: Research Centre UNIZA, University of Žilina, Univerzitná 8215/1, 010 26, Žilina, Slovakia

© The Author(s) 2025

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