Previous experiments observed a 4^+ state in the N=28 nucleus ^44S and suggested that this state may exhibit a hindered E2-decay rate, inconsistent with being a member of the collective ground state band. We populate this state via two-proton knockout from a beam of exotic ^46Ar projectiles and measure its lifetime using the recoil distance method with the GRETINA γ-ray spectrometer. The result, 76(14)_stat(20)_syst ps, implies a hindered transition of B(E2;4^+→2_1^+)=0.61(19) single-particle or Weisskopf units strength and supports the interpretation of the 4^+ state as a K=4 isomer, the first example of a high-K isomer in a nucleus of such low mass.
Isomeric Character of the Lowest Observed 4^+ State in ^44S
RECCHIA, FRANCESCO;
2017
Abstract
Previous experiments observed a 4^+ state in the N=28 nucleus ^44S and suggested that this state may exhibit a hindered E2-decay rate, inconsistent with being a member of the collective ground state band. We populate this state via two-proton knockout from a beam of exotic ^46Ar projectiles and measure its lifetime using the recoil distance method with the GRETINA γ-ray spectrometer. The result, 76(14)_stat(20)_syst ps, implies a hindered transition of B(E2;4^+→2_1^+)=0.61(19) single-particle or Weisskopf units strength and supports the interpretation of the 4^+ state as a K=4 isomer, the first example of a high-K isomer in a nucleus of such low mass.Pubblicazioni consigliate
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