Approaching the “island of inversion”: P34

P. C. Bender, C. R. Hoffman, M. Wiedeking, J. M. Allmond, L. A. Bernstein, J. T. Harke, D. L. Bleuel, R. M. Clark, P. Fallon, B. L. Goldblum, T. A. Hinners, H. B. Jeppesen, Sangjin Lee, I.-Y. Lee, S. R. Lesher, A. O. Macchiavelli, M. A. McMahan, D. Morris, M. Perry, L. Phair, N. D. Scielzo, S. L. Tabor, Vandana Tripathi, and A. Volya
Phys. Rev. C 80, 014302 – Published 6 July 2009

Abstract

Yrast states in P34 were investigated using the O18(O18,pn) reaction at energies of 20, 24, 25, 30, and 44 MeV at Florida State University and at Lawrence Berkeley National Laboratory. The level scheme was expanded, γ-ray angular distributions were measured, and lifetimes were inferred with the Doppler-shift attenuation method by detecting decay protons in coincidence with one or more γ rays. The results provide a clearer picture of the evolution of structure approaching the “island of inversion,” particularly how the one- and two-particle-hole (ph) states fall in energy with increasing neutron number approaching inversion. However, the agreement of the lowest few states with pure sd shell model predictions shows that the level scheme of P34 is not itself inverted. Rather, the accumulated evidence indicates that the 1-ph states start at 2.3 MeV. A good candidate for the lowest 2-ph state lies at 6236 keV, just below the neutron separation energy of 6291 keV. Shell model calculations made using a small modification of the WBP interaction reproduce the negative-parity, 1-ph states rather well.

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  • Received 16 April 2009

DOI:https://doi.org/10.1103/PhysRevC.80.014302

©2009 American Physical Society

Authors & Affiliations

P. C. Bender1, C. R. Hoffman1, M. Wiedeking2,3, J. M. Allmond4, L. A. Bernstein3, J. T. Harke3, D. L. Bleuel3, R. M. Clark2, P. Fallon2, B. L. Goldblum5, T. A. Hinners1, H. B. Jeppesen2, Sangjin Lee1, I.-Y. Lee2, S. R. Lesher3, A. O. Macchiavelli2, M. A. McMahan2, D. Morris1, M. Perry1, L. Phair2, N. D. Scielzo3, S. L. Tabor1, Vandana Tripathi1, and A. Volya1

  • 1Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
  • 2Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 3Lawrence Livermore National Laboratory, Livermore, California 94551, USA
  • 4Department of Physics, University of Richmond, Virginia 23173, USA
  • 5Department of Nuclear Engineering, University of California, Berkeley, California 94720, USA

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Issue

Vol. 80, Iss. 1 — July 2009

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