Properties of γ -decaying isomers and isomeric ratios in the Sn100 region

Abstract

Half-lives and energies of γ rays emitted in the decay of isomeric states of nuclei in the vicinity of the doubly magic 100 Sn were measured in a decay spectroscopy experiment at Rikagaku Kenkyusho (The Institute of Physical and Chemical Research) of Japan Nishina Center. The measured half-lives, some with improved precision, are consistent with literature values. Three new results include a 55-keV E2 γ ray from a new (4 + ) isomer with T 1/2 = 0.23(6) μs in 92 Rh, a 44-keV E2 γ ray from the (15 + ) isomer in 96 Ag, and T 1/2 (6 + ) = 13(2) ns in 98 Cd. Shell-model calculations of electromagnetic transition strengths in the (p 1/2 ,g 9/2 ) model space agree with the experimental results. In addition, experimental isomeric ratios were compared to the theoretical predictions derived with an abrasion-ablation model and the sharp cutoff model. The results agreed within a factor of 2 for most isomers. From the nonobservation of time-delayed γ rays in 100 Sn, new constraints on the T 1/2 , γ -ray energy, and internal conversion coefficients are proposed for the hypothetical isomer in 100 Sn.

Properties of $\gamma $-decaying Isomers in the $^{100}$Sn Region Revisited

“…The obtained half-life value is consistent with the result of 0.23(6) µs from Ref. [3] supporting the (4 + ) assignment for the isomer in 92 Rh [3,13].…”

“…The transition energy from the (15 + ) isomer to the (13 + ) state of 96 Ag was measured by Park et al [3] for the first time and determined to be 43.7(2) keV. By choosing an appropriate time window of 500 ns ≤ t ≤ 6.5 µs, a preliminary value of 44.1 (5) keV for this transition could be obtained in the present work which is consistent within the error bars [13].…”

“…In general, the results from the SM calculation are in a good agreement with the experimentally deduced B(σλ)-values except for isomers in 92,94 Ru and 98 Cd [13]. Park et al [3] reported on two new low-energy isomeric transitions in 92 Rh and 96 Ag. By constraining the DGF time window, prompt flash events are suppressed in the γ-ray spectrum.…”

“…Due to the shell structure of atomic nuclei and the residual interaction between individual nucleons, the region south-west of 100 Sn has a high abundance of different types of isomers. Recently, Park et al [3] presented results on γ-decaying isomers and isomeric ratios in this region. The data analysed in this work was obtained independently in a similar experiment and provides further information on γ-decaying isomers in that region.…”

Spectroscopy and excited-state g factors in weakly collective Cd111 : Confronting collective and microscopic models

“…The SR88MHJM Hamiltonian [21,[54][55][56] employed for these calculations assumes an inert 88 Sr core and includes orbits up to Z = 50 and N = 82. Specifically, the model space is π(p 1 2 , g 9 2 )ν(d 5 2 , g 7 2 , d 3 2 , s 1 2 , h 11 2 ).…”