Physics Letters B (Dec 2014)

Neutron occupancy of the 0d5/2 orbital and the N=16 shell closure in 24O

  • K. Tshoo,
  • Y. Satou,
  • C.A. Bertulani,
  • H. Bhang,
  • S. Choi,
  • T. Nakamura,
  • Y. Kondo,
  • S. Deguchi,
  • Y. Kawada,
  • Y. Nakayama,
  • K.N. Tanaka,
  • N. Tanaka,
  • Y. Togano,
  • N. Kobayashi,
  • N. Aoi,
  • M. Ishihara,
  • T. Motobayashi,
  • H. Otsu,
  • H. Sakurai,
  • S. Takeuchi,
  • K. Yoneda,
  • F. Delaunay,
  • J. Gibelin,
  • F.M. Marqués,
  • N.A. Orr,
  • T. Honda,
  • T. Kobayashi,
  • T. Sumikama,
  • Y. Miyashita,
  • K. Yoshinaga,
  • M. Matsushita,
  • S. Shimoura,
  • D. Sohler,
  • J.W. Hwang,
  • T. Zheng,
  • Z.H. Li,
  • Z.X. Cao

Journal volume & issue
Vol. 739
pp. 19 – 22

Abstract

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One-neutron knockout from 24O leading to the first excited state in 23O has been measured for a proton target at a beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of 23O was reconstructed from the measured four momenta of the 22O fragment and emitted neutron. A sharp peak was found at Edecay=50±3 keV, corresponding to an excited state in 23O at 2.78±0.11 MeV, as observed in previous measurements. The longitudinal momentum distribution for this state was consistent with d-wave neutron knockout, providing support for a Jπ assignment of 5/2+. The associated spectroscopic factor was deduced to be C2S(0d5/2)=4.1±0.4 by comparing the measured cross section (σ−1nexp=61±6 mb) with a distorted wave impulse approximation calculation. Such a large occupancy for the neutron 0d5/2 orbital is in line with the N=16 shell closure in 24O.