Excited State Properties in Neutron-rich Nuclei near N = 40

ORAL

Abstract

The neutron-rich nuclei near N = 40 have recently been the focus of many experimental and theoretical efforts. In this region, the competing energy cost for promoting pairs of nucleons across either Z = 28 or N = 40 and the energy gain from residual nucleon-nucleon interactions gives rise to several low-energy 0$^{+}$ states and is a hallmark of shape coexistence. Low-energy 0$^{+}$ states have been observed in $^{68}$Ni, and predicted for other nuclei in the region. Recent theoretical calculations are able to reproduce the energies of known states in $^{68}$Ni and stress the importance of the tensor component of the monopole interaction. Yet, while energies of the levels are a useful comparison, a more stringent test is the reproduction of level lifetimes, where the predicted half-lives can vary by several orders of magnitude depending on the interaction. To further benchmark theoretical calculations in this region, a setup designed to measure level lifetimes has been constructed. A description of the array and preliminary results will be presented.

*This work was supported by the DOE NNSA award No. DE-NA0000979, NSF contract No. PHY1102511, DOE SC NP contract No. DE-AC-06CH11357 and grant No. DE-FG02-94ER40834

Authors

  • B.P. Crider

    • NSCL/MSU
  • C.J. Prokop

    • MSU/NSCL
    • NSCL/MSU
  • Sean Liddick

    • NSCL/MSU
  • C.J. Chiara

    • Army Research Lab, ORAU
  • A.D. Ayangeakaa

    • ANL
    • Argonne National Laboratory
  • J.J. Carroll

    • USArmy Research Laboratory
    • Army Research Lab
  • J. Chen

    • NSCL/MSU
  • Helena M. David

    • ANL
    • Argonne National Laboratory
  • S. Go

    • UTK
  • Robert Grzywacz

    • University of Tennessee
    • University of Tennessee, ORNL
    • UTK
  • J. Harker

    • UMD
  • R.V.F. Janssens

    • ANL
  • T. Lauritsen

    • ANL
  • Dariusz Seweryniak

    • ANL
    • Argonne National Laboratory
  • W.B. Walters

    • UMD