<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>β</mi></math> decay of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>T</mi><mi>z</mi></msub><mo>=</mo><mo>−</mo><mn>2</mn></mrow></math> nucleus <math xmlns="http://www.w3.org/1998/Math/MathML"><mmultiscripts><mi>Se</mi><mprescripts></mprescripts><none></none><mn>64</mn></mmultiscripts></math> and its descendants: The <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>T</mi><mo>=</mo><mn>2</mn></mrow></math> isobaric multiplet

P. Aguilera; F. Molina; B. Rubio; S. E. A. Orrigo; W. Gelletly; Y. Fujita; J. Agramunt; A. Algora; V. Guadilla; A. Montaner-Pizá; A. I. Morales; H. F. Arellano; P. Ascher; B. Blank; M. Gerbaux; J. Giovinazzo; T. Goigoux; S. Grévy; T. Kurtukian Nieto; C. Magron; J. Chiba; D. Nishimura; S. Yagi; H. Oikawa; Y. Takei; D. S. Ahn; P. Doornenbal; N. Fukuda; N. Inabe; T. Kubo; S. Kubono; S. Nishimura; Y. Shimizu; T. Sumikama; H. Suzuki; H. Takeda; J. Wu; V. H. Phong; G. G. Kiss; P.-A. Söderström; M. Tanaka; F. Diel; D. Lubos; S. Lenzi; G. de Angelis; D. Napoli; C. Borcea; A. Boso; R. B. Cakirli; E. Ganioglu; G. de France; S. Go

doi:10.1103/gkvv-y4w8

Editors' Suggestion

$β$ decay of the $T_{z} = - 2$ nucleus ${}^{64}{Se}$ and its descendants: The $T = 2$ isobaric multiplet

P. Aguilera ^1,2,3,*, F. Molina ^2,4,5, B. Rubio ^1,†, S. E. A. Orrigo ¹, W. Gelletly ^1,6, Y. Fujita ^7,8, J. Agramunt¹, A. Algora ^1,9, V. Guadilla ^1,10 et al.

A. Montaner-Pizá¹, A. I. Morales ¹, H. F. Arellano ¹¹, P. Ascher ¹², B. Blank ¹², M. Gerbaux ¹², J. Giovinazzo ¹², T. Goigoux¹², S. Grévy ¹², T. Kurtukian Nieto ¹², C. Magron¹², J. Chiba¹³, D. Nishimura¹³, S. Yagi¹³, H. Oikawa¹⁴, Y. Takei¹⁴, D. S. Ahn¹⁵, P. Doornenbal ¹⁵, N. Fukuda¹⁵, N. Inabe¹⁵, T. Kubo ¹⁵, S. Kubono¹⁵, S. Nishimura ¹⁵, Y. Shimizu¹⁵, T. Sumikama¹⁵, H. Suzuki¹⁵, H. Takeda¹⁵, J. Wu¹⁵, V. H. Phong ^16,15, G. G. Kiss ^15,17, P.-A. Söderström ^15,18, M. Tanaka⁸, F. Diel¹⁹, D. Lubos²⁰, S. Lenzi ^21,3, G. de Angelis ²², D. Napoli²², C. Borcea ²³, A. Boso^21,3, R. B. Cakirli ^24,25,26, E. Ganioglu ²⁴, G. de France ²⁷, and S. Go^15,28

¹Instituto de Física Corpuscular, CSIC-Universitat de Valéncia, E-4980 Paterna, Spain
²Centro de Investigación en Física Nuclear y Espectroscopía de Neutrones CEFNEN, Comisión Chilena de Energía Nuclear, Nueva Bilbao, 12501 Las Condes, Santiago, Chile
³Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova I-35131, Italy
⁴Millennium Institute for Subatomic Physics at High Energy Frontier - SAPHIR, Fernández Concha 700, Las Condes, Santiago, Chile
⁵Departamento de Ciencias Físicas, Universidad Andres Bello, Sazié 2212, 837-0136 Santiago, Chile
⁶Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
⁷Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan
⁸Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
⁹HUN-REN Institute for Nuclear Research (ATOMKI), H-4001 Debrecen, Hungary
¹⁰Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland
¹¹Department of Physics-FCFM, University of Chile, Av. Blanco Encalada 2008, RM 8370449 Santiago, Chile
¹²Centre d'Etudes Nucléaires de Bordeaux-Gradignan, UMR 5797 Université de Bordeaux CNRS/IN2P3, 19 Chemin du Solarium, CS10120, 33175 Gradignan Cedex, France
¹³Department of Natural Sciences, Tokyo City University, Setagaya-ku, Tokyo 158-8557, Japan
¹⁴Department of Physics, Tokyo University of Science, Noda, Chiba 278-8510, Japan
¹⁵RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
¹⁶Faculty of Physics, VNU Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam
¹⁷HUN-REN Institute for Nuclear Research, Bem tér 18/c, Debrecen 4026, Hungary
¹⁸Extreme Light Infrastructure-Nuclear Physics (ELI-NP)/Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), Str. Reactorulu, Măgurele 077125, Romania
¹⁹Institute of Nuclear Physics, University of Cologne, D-50937 Cologne, Germany
²⁰Physik Department E12, Technische Universität München, D-85748 Garching, Germany
²¹Dipartimento di Fisica dell' Università degli Studi di Padova, Padova I-35131, Italy
²²Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro I-35020, Italy
²³National Institute for Physics and Nuclear Engineering IFIN-HH, P.O. Box MG-6, Bucharest-Magurele, Romania
²⁴Department of Physics, Istanbul University, Istanbul 34134, Turkey
²⁵Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
²⁶ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt, Germany
²⁷Grand Accélérateur National d'Ions Lourds, B.P. 55027, F-14076 Caen Cedex 05, France
²⁸Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA

^*Contact author: pablo.aguilera@pd.infn.it
^†Contact author: berta.rubio@ific.uv.es

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Phys. Rev. C 112, 054319 – Published 20 November, 2025

DOI: https://doi.org/10.1103/gkvv-y4w8

Abstract

In this paper we present our results on the decay of ${}^{64}{Se}$ . It is the heaviest $T_{z} = - 2$ nucleus that both $β$ decays and has a stable mirror partner ( $T_{z} = + 2$ ), thus allowing comparison with charge exchange reaction studies. The $β$ decays of ${}^{64}{Se}$ and its descendants were studied at the RIKEN Nishina Center (Japan) following their production in the fragmentation of ${}^{78}{Kr}$ on a beryllium target. $β$ -Delayed $γ$ -ray and particle radiation was identified for each of the nuclei in the decay chain allowing us to obtain decay schemes for ${}^{64}{Se}$ , ${}^{64}{As}$ , and ${}^{63}{Ge}$ . Thus new excited states could be found for the descendant nuclei, including the interesting case of the $N = Z$ nucleus ${}^{64}{Ge}$ . Furthermore, we observed for the first time the $β$ -delayed proton emission of ${}^{64}{Se}$ and ${}^{64}{As}$ . Based on these results we obtained proton branching ratios of $48.0 (9) %$ in ${}^{64}{Se}$ decay and $4.4 (1) %$ in ${}^{64}{As}$ decay. We obtained a half-life value of $22.5 (6) ms$ for ${}^{64}{Se}$ decay and half-lives slightly more precise than those in the literature for each nucleus involved in the decay chain. Using our results on the excited levels of ${}^{64}{As}$ and the mass excess in the literature for ${}^{63}{Ge}$ we obtained $- 39588 (50) keV$ for the mass excess of ${}^{64}{As}$ . Then based on the isobaric mass multiplet equation we obtained the mass excess of $- 27429 (88) keV$ for ${}^{64}{Se}$ by extrapolation. The mirror process of ${}^{64}{Se} β$ decay, the charge exchange reaction ${}^{64}{Zn} {({}^{3}{He}, t)}^{64} Ga$ , has already been measured allowing us to study the mirror symmetry through the comparison of the weak force ( $β$ a decay) and strong force (charge exchange reaction). An interpretation of the decay schemes based on the idea of the antisnalogue tate is proposed.

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$β$ decay of the $T_{z} = - 2$ nucleus ${}^{64}{Se}$ and its descendants: The $T = 2$ isobaric multiplet

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β decay of the Tz=−2 nucleus Se64 and its descendants: The T=2 isobaric multiplet

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$β$ decay of the $T_{z} = - 2$ nucleus ${}^{64}{Se}$ and its descendants: The $T = 2$ isobaric multiplet