Characteristics of the 21/2+ isomer in 93Mo: Toward the possibility of enhanced nuclear isomer decay

Abstract To discuss whether an enhanced isomer decay is a preferred process in a plasma environment it is required to know the structure of the isomer as well as the nearby states. The spin-21/2, 6.85-hour high-spin isomer in Mo 93 is investigated within a shell model which well describes nuclei in this mass region. By using the obtained wave-functions which correctly reproduce the observed B ( E 2 ) , B ( E 4 ) , and B ( M 1 ) transitions, characteristics of the isomer are shown in comparison with the isomeric states in neighboring nuclei. Calculations suggest that these high-spin isomers are formed with almost pure single-particle-like configurations. The 93 Mo 21 / 2 + isomer has the predominant configuration π ( g 9 / 2 ) 8 2 ⊗ ν d 5 / 2 lying below the 15 / 2 + , 17 / 2 + , and 19 / 2 + states due to neutron–proton interaction, which is the physical origin of its long lifetime. The key E 2 transition that connects the 21 / 2 + isomer to the upper 17 / 2 + level is predicted to be substantial (3.5 W.u.), and therefore there is a real prospect for observing induced isomer deexcitation.