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  • Letter
  • Open Access

Broken seniority symmetry in the semimagic proton mid-shell nucleus Rh95

B. Das1,2,*, B. Cederwall1,†, C. Qi1, M. Górska2, P. H. Regan3,4, Ö. Aktas1, H. M. Albers2, A. Banerjee2,‡, M. M. R. Chishti3 et al.

J. Gerl2, N. Hubbard2,5,6, S. Jazrawi3,4, J. Jolie7, A. K. Mistry2,5, F. Nowacki8, M. Polettini9,10, A. Yaneva2,7, U. Ahmed5,6, S. Alhomaidhi2,5,6,11, A. Algora12,13, C. Appleton14, T. Arici2, S. Bagchi15, G. Benzoni10, J. Benito16, A. Blazhev7, P. Boutachkov2, A. Bracco9,10, A. M. Bruce17, M. Brunet3, R. Canavan3,4, T. Davinson14, T. Dickel2,18, A. Esmaylzadeh7, L. M. Fraile16, E. Haettner2, O. Hall14, G. Häfner19,7, H. Heggen2, Ch. Hornung2, J. P. Hucka5, P. R. John5, D. Kahl14, V. Karayonchev7, R. Kern5, R. Knöbel2, A. Korgul20, G. Kosir21,22, I. Kojouharov2, D. Kostyleva2, N. Kuzminchuk2, N. Kurz2, R. Liotta1, R. Lozeva19, M. Mikolajczuk20,2, I. Mukha2, P. Napiralla5, R. Page23, C. M. Petrache19, N. Pietralla5, S. Pietri2, W. R. Plaß2,18, Zs. Podolyák3, J.-M. Régis7, M. Rudigier5, H. Rösch5, P. Ruotsalainen24, E. Sahin2,5,6, V. Sánchez-Tembleque16, H. Schaffner2, C. Scheidenberger2, F. Schirru2, L. Sexton14, B. S. Nara Singh25, A. Sharma26, R. Shearman4, M. Si19, Y. K. Tanaka27, J. Vasiljević1, J. Vesić21, J. Vilhena28, H. Weick2, H. J. Wollersheim2, V. Werner5,6, J. Wiederhold5, W. Witt5, P. J. Woods14, G. Zimba24, and J. Zhao2

  • 1KTH Royal Institute of Technology, 10691 Stockholm, Sweden
  • 2GSI Helmholtzzentrum für Schwerionenforschung GmbH - Darmstadt, 64291 Germany
  • 3Department of Physics, University of Surrey - Guildford, GU2 7XH, UK
  • 4National Physical Laboratory - Teddington, Middlesex, TW11 0LW, UK
  • 5Institut für Kernphysik, Technische Universität Darmstadt - Darmstadt, 64289 Germany
  • 6Helmholtz Forschungsakademie Hessen für FAIR (HFHF), GSI Helmholtzzentrum für Schwerionenforschung, Campus Darmstadt, 64289 Darmstadt, Germany
  • 7Institut für Kernphysik der Universität zu Köln - Zülpicher Strasse 77, D-50937 Köln, Germany
  • 8Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
  • 9Dipartimento di Fisica, Universitã degli Studi di Milano - Milano, 20133 Italy
  • 10INFN, Sezione di Milano - Milano, 20133 Italy
  • 11King Abdulaziz City for Science and Technology (KACST), Riyadh 11442, Saudi Arabia
  • 12Instituto de Fisica Corpuscular, CSIC-Universidad de Valencia - E-46071 Valencia, Spain
  • 13Institute for Nuclear Research (ATOMKI), Bem ter 18/c, H-4026 Debrecen, Hungary
  • 14University of Edinburgh, School of Physics and Astronomy - Edinburgh EH9 3FD, UK
  • 15Indian Institute of Technology, Dhanbad-826004, Jharkhand, India
  • 16Grupo de Física Nuclear and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa - E-28040 Madrid, Spain
  • 17School of Computing Engineering and Mathematics, University of Brighton - Brighton, BN2 4AT UK
  • 18Justus Liebig University, 35390 Giessen, Germany
  • 19Université Paris-Saclay, IJCLab, CNRS/IN2P3, F-91405 Orsay, France
  • 20Faculty of Physics, University of Warsaw, PL 02-093, Warsaw, Poland
  • 21Jozef Stefan Institute - Jamova cesta 39, 1000 Ljubljana, Slovenia
  • 22Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
  • 23Department of Physics, Oliver Lodge Laboratory, University of Liverpool Liverpool L69 7ZE, UK
  • 24University of Jyväskylä - Seminaarinkatu 15, 40014 Jyväskylän yliopisto, Finland
  • 25SUPA, School of Computing, Engineering and Physical Sciences, University of the West of Scotland - Paisley, PA1 2BE UK
  • 26Department of Physics, Indian Institute of Technology Ropar, Rupnagar-140 001, Punjab, India
  • 27High-Energy Nuclear Physics Laboratory, RIKEN, 351-0198 Saitama, Japan
  • 28Laboratoire de Physique de la Matiére Condensé et Nanostructures, Université Lyon I, CNRS, UMR 5586, Domaine scientifique de la Doua - F-69622 Villeurbanne Cedex, France

  • *Corresponding author: b.das@gsi.de
  • †Corresponding author: bc@kth.se
  • ‡Present address: Saha Institute of Nuclear Physics, Kolkata-700064, India
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Phys. Rev. Research 6, L022038 – Published 10 May, 2024

DOI: https://doi.org/10.1103/PhysRevResearch.6.L022038

Abstract

Lifetime measurements of low-lying excited states in the semimagic (N=50) nucleus Rh95 have been performed by means of the fast-timing technique. The experiment was carried out using γ-ray detector arrays consisting of LaBr3(Ce) scintillators and germanium detectors integrated into the DESPEC experimental setup commissioned for the Facility for Antiproton and Ion Research (fair) Phase-0, Darmstadt, Germany. The excited states in Rh95 were populated primarily via the β decays of Pd95 nuclei, produced in the projectile fragmentation of a 850 MeV/nucleon Xe124 beam impinging on a 4g/cm2Be9 target. The deduced electromagnetic E2 transition strengths for the γ-ray cascade within the multiplet structure depopulating from the isomeric Iπ=21/2+ state are found to exhibit strong deviations from predictions of standard shell model calculations which feature approximately conserved seniority symmetry. In particular, the observation of a strongly suppressed E2 strength for the 13/2+→9/2+ ground state transition cannot be explained by calculations employing standard interactions. This remarkable result may require revision of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations, and might also point to the need for including three-body forces in the Hamiltonian.

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Phys. Rev. Research 6, L022038– Published 10 May, 2024
  • Received 12 October 2022
  • Revised 31 January 2024
  • Accepted 25 April 2024
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