First decay study of the very neutron-rich isotope93Br

Abstract

The decay of the mass-separated, very neutron-rich isotope 93 Br has been studied by ␥ spectroscopy. A level scheme of its daughter 93 Kr has been constructed. Level energies, ␥-ray branching ratios, and multipolarities suggest spins and parities which are in accord with a smooth systematics of the Nϭ57 isotones for Zр40, suggesting the Nϭ56 subshell closure still to be effective in Kr isotopes. So far, there is no indication of a progressive onset of deformation in neutron-rich Kr isotopes.

Beta-decay properties of the neutron-rich 94–99Kr and 142–147Xe isotopes

“…Recent experimental data [42] suggest that no sizeable deformation appears in the Kr chain below N=60. G. Lhersonneau and co-workers reached a similar conclusion from a 93 Br decay study [43]. Laser-spectroscopy measurements [44] have demonstrated that 96 Kr (N=60) is only moderately deformed.…”

β-decay study of neutron-rich bromine and krypton isotopes

“…Transitions assigned to 93 Br decay and a partial decay scheme were later reported in [7]. The half-life of 102(10) ms differs by more than 3σ from the value of 152(8) ms found in this work.…”

“…5. A conversion coefficient for the 117 keV transition, α K = 0.058(10) [7], is included in the presented decay scheme. The apparent beta feeding shown is deducted from the scheme.…”

“…The β-decay scheme of 93 Br was previously reported in [7] while the half-life comes from an earlier report [8]. The β-delayed branching ratio was given in reference [8] as P n = 10(5)% and later revised by the same group to 68(7)% [7]. The detailed discussion of differences in results between our value and that of previous work is presented in section III A.…”

“…It is worth noting that both of its decay daughters, 92,93 Kr, are included therein. The β-decay scheme of 93 Br was previously reported in [7] while the half-life comes from an earlier report [8]. The β-delayed branching ratio was given in reference [8] as P n = 10(5)% and later revised by the same group to 68(7)% [7].…”