First direct search for and decay of 144Sm and decay of 154Sm

P. Belli; R. Bernabei; R. S. Boiko; F. Cappella; V. Caracciolo; R. Cerulli; F. A. Danevich; A. Di Marco; A. Incicchitti; B. N. Kropivyansky; M. Laubenstein; S. Nisi; D. V. Poda; O. G. Polischuk; V. I. Tretyak

doi:10.1140/epja/i2019-12911-3

EPJ

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2023 Impact factor 2.6

Hadrons and Nuclei

Eur. Phys. J. A (2019) 55: 201
https://doi.org/10.1140/epja/i2019-12911-3

Regular Article - Experimental Physics

First direct search for $2 \epsilon$ and $\epsilon\beta^{+}$ decay of ¹⁴⁴Sm and $2 \beta^{-}$ decay of ¹⁵⁴Sm

P. Belli¹^,2, R. Bernabei¹^,2^*, R. S. Boiko³^,4, F. Cappella⁵^,6, V. Caracciolo¹^,2, R. Cerulli¹^,2, F. A. Danevich³, A. Di Marco¹^,2, A. Incicchitti⁵^,6, B. N. Kropivyansky³, M. Laubenstein⁷, S. Nisi⁷, D. V. Poda³^,8, O. G. Polischuk³^,2 and V. I. Tretyak³

¹ INFN sezione Roma “Tor Vergata”, I-00133, Rome, Italy
² Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133, Rome, Italy
³ Institute for Nuclear Research, National Academy of Sciences of Ukraine, 03028, Kyiv, Ukraine
⁴ National University of Life and Environmental Sciences of Ukraine, 03041, Kyiv, Ukraine
⁵ INFN sezione Roma, I-00185, Rome, Italy
⁶ Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185, Rome, Italy
⁷ INFN, Laboratori Nazionali del Gran Sasso, I-67100, Assergi (AQ), Italy
⁸ CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, 91405, Orsay, France

^* e-mail: rita.bernabei@roma2.infn.it

Received: 15 July 2019
Accepted: 4 October 2019
Published online: 14 November 2019

Abstract

The first direct search for the double electron capture ( $2\epsilon$ ) and the electron capture with positron emission ( $\epsilon\beta^+$ ) in ¹⁴⁴Sm to the ground state and to the excited levels of ¹⁴⁴Nd was realized by measuring --over 1899h-- a 342g sample of highly purified samarium oxide (Sm₂O₃) with the ultra-low background HP-Ge $\gamma$ spectrometer GeCris (465cm³) at the STELLA facility of the Gran Sasso National Laboratory (LNGS). No effect was observed and half-life limits were estimated at the level of $T_{1/2} \sim (0.1 - 1.3) \times 10^{20}$ yr (90% C.L.). Moreover, for the first time half-life limits of the double beta ( $2\beta^-$ ) decay of ¹⁵⁴Sm to several excited levels of ¹⁵⁴Gd have been set; they are at the level of $T_{1/2} \sim (0.06 - 8) \times 10^{20}$ yr (90% C.L.).