Physics Letters B (May 2018)

Enhanced collectivity in 12Be

  • C. Morse,
  • E.A. McCutchan,
  • H. Iwasaki,
  • C.J. Lister,
  • V.M. Bader,
  • D. Bazin,
  • S. Beceiro Novo,
  • P. Chowdhury,
  • A. Gade,
  • T.D. Johnson,
  • C. Loelius,
  • E. Lunderberg,
  • E. Merchan,
  • V.S. Prasher,
  • F. Recchia,
  • A.A. Sonzogni,
  • D. Weisshaar,
  • K. Whitmore

Journal volume & issue
Vol. 780
pp. 227 – 232

Abstract

Read online

Electromagnetic quadrupole transition strength is a sensitive probe of the evolution of the structure of nuclei, particularly the competition between collectivity and magicity. We have performed a new lifetime measurement of the 21+ state of 12Be to study the interplay of these phenomena. The lifetime was measured with the Doppler Shift Attenuation Method using the γ-ray detector GRETINA. Excited states of 12Be were produced via inelastic scattering at 55 MeV/nucleon, using several different targets to control for systematic uncertainties in the stopping powers. The lifetime is determined to be τ=1.38±0.10(stat)±0.19(sys) ps, which is about half the previously reported value at twice the precision. The reduced transition strength deduced from this result is B(E2;21+→01+)=14.2±1.0(stat)±2.0(sys) e2fm4, which supports the quenching of the N=8 shell gap in 12Be. Keywords: Lifetimes, Nuclear transition probabilities, Collectivity