Isomeric Character of the Lowest Observed $4^+$ State in $^{44}$S
Résumé
Previous experiments observed a 4+ state in the N=28 nucleus S44 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 Ar46 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+→21+)=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.