Identification of a new isomeric state in <sup>76</sup>Zn following the β decay of <sup>76</sup>Cu

ORAL

Abstract

Shell evolution far from stability can be explored by measuring the properties of isomeric states, which provide a sensitive probe of the microscopic structure of the nucleus. Beta decay is an attractive method for isomer identification because daughter nuclei can be populated in an excited state which subsequently decays to the ground state through one or more isomeric transitions. A β-decay experiment was recently performed at the National Superconducting Cyclotron Laboratory (NSCL) to identify and study isomeric states in the vicinity of the doubly magic nucleus 78Ni. Radioactive ions produced by beam fragmentation at the NSCL's Coupled Cyclotron Facility were implanted into a CeBr3 scintillator detector coupled to a position-sensitive photomultiplier tube (PSPMT). Ancillary arrays of HPGe clover and LaBr3 detectors were positioned around the implantation detector to measure β-delayed γ rays. The entire suite of detectors was instrumented with the NSCL Digital Data Acquisition System (DDAS). Dynode traces recorded by DDAS were analyzed to selectively identify isomeric transitions. The previously observed 2634-keV level in 76Zn, populated following the β decay of 76Cu, was identified as isomeric with a half-life of 25.4(4) ns. A combination of timing and γ-ray spectroscopy was used to confirm this assignment. Shell-model calculations were performed which indicate that this state may be a high-spin negative-parity state formed by the occupation of the neutron 0g9/2 orbital. The experimental results and theoretical interpretation will be presented.

*This work was supported by the US Department of Energy (DOE) National Nuclear Security Administration through Grant No. DOE-DE-NA0003906, the Nuclear Science and Security Consortium, under Award No. DE-NA0003180, and the DOE, Office of Nuclear Physics, under Grant No. DE-SC0020451.

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Presenters

  • Aaron Chester

    • Michigan State University
    • National Superconducting Cyclotron Laboratory

Authors

  • Aaron Chester

    • Michigan State University
    • National Superconducting Cyclotron Laboratory

  • Alex Brown

    • Michigan State University
    • Michigan State Universtiy
    • National Superconducting Cyclotron Laboratory; Department of Physics and Astronomy, Michigan State University

  • Michael P Carpenter

    • Argonne National Laboratory
    • ANL

  • James J Carroll

    • DEVCOM/Army Research Laboratory

  • C.J. J Chiara

    • DEVCOM/Army Research Laboratory
    • ANL

  • Patrick Copp

    • Argonne National Laboratory
    • Argonne national Laboratory

  • Benjamin P Crider

    • Mississippi State Univ
    • Mississippi State University
    • Department of Physics and Astronomy, Mississippi State University

  • Jason T Harke

    • Lawrence Livermore National Laboratory
    • Lawrence Livermore Natl Lab

  • Daniel E Hoff

    • University of Massachusetts Lowell
    • Lawrence Livermore National Laboratory

  • Kay Kolos

    • Lawrence Livermore Natl Lab
    • LLNL
    • Lawrence Livermore National Laboratory

  • Sean N Liddick

    • National Superconducting Cyclotron Laboratory
    • Michigan State University, NSCL/FRIB
    • NSCL
    • National Superconducting Cyclotron Laboratory; Department of Chemistry, Michigan State University
    • Michigan State University
    • National Superconducting Cyclotron Laboratory; Michigan State University
    • FRIB

  • Brenden Longfellow

    • Lawrence Livermore National Laboratory
    • Lawrence Livermore Natl Lab

  • Mejdi J Mogannam

    • National Superconducting Cyclotron Laboratory; Department of Chemistry, Michigan State University

  • Timilehin H Ogunbeku

    • Mississippi State University
    • Department of Physics and Astronomy, Mississippi State University

  • Andrea L Richard

    • Lawrence Livermore Natl Lab
    • National Superconducting Cyclotron Labor
    • Lawrence Livermore National Laboratory

  • Olalekan A Shehu

    • Department of Physics and Astronomy, Mississippi State University
    • University of Rhode Island

  • Ronald Unz

    • Department of Physics and Astronomy, Mississippi State University

  • Yongchi Xiao

    • Department of Chemistry, University of Kentucky
    • Michigan State University
    • University of Kentucky