The high-spin single-particle structure of¹²¹I

Abstract

he high-spin level slructure of "'1 has been established above the first yrast 'band tenination slale', which occurs at an excitation energy of 5.43 MeV with I" = 39/2-, using data from the Eurogam a m y . The high-spin Svychm exhibits an irregular set of levels consistent with non~collective behaviour. A band terminating stale at 9.24 MeV with I" = 55/2has been -identified. Comparison with total Routhim surface cran!dng calculations suggest a maximally aligned [nh11/2&,&~/~-@ [ ~h f , , ~l ~6 + oblate configuration for this state relative lo the 'I4Sn core. NUCLEAR REACTIONS lQSi + 96Zr at 135 MeV, enriched large&. HpGe detectors, BGO suppression shields, measured E, deduced I", comparison with TRS cranking calculations.

Highly deformed high-spin band in125I

“…In the A = 125 mass region, non-collective maximally aligned states have been observed in 121 I [1], 125 I [2], 124 Xe [3], 123 Cs [4], and tentatively in 124 Ba [5], where all particles outside the 114 50 Sn 64 core align their angular momenta along the same axis to generate terminating states. Furthermore, non-collective states above these terminating states have been observed.…”

Evidence for noncollective oblate structures at high spin inCs123

“…8 we compare the observed bands with the predicted [1,6] and [1,4] configurations. The [1,4] configuration contains four h 11/2 neutrons while the distribution of neutrons between orbitals of g 7/2 d 5/2 and d 3/2 s 1/2 character might vary.…”

“…Among the calculated negative-parity bands the ␣ =−1/2 signature branch of the [1,6] configuration, i.e., the h 11/2 1 11/2 6 structure, is yrast up to spin 28. The positive signature of this configuration is predicted to lie about 500 keV higher in energy.…”

“…This minimum is considerably closer in energy to the unfavored branch in agreement with the experimental observation. Therefore, band 1 may correspond to the [1,6] configuration, having triaxial shape with ␥ Ӎ −30°. The predicted yrare configuration in this spin region is the [(1)1,6], i.e., the ͓g 9/2 −1 h 11/2 1 ͔ h 11/2 6 configuration, which has no signature splitting.…”

“…[4][5][6][7]) and Xe [3,8,9] nuclei have revealed the presence of irregular structures on top of regular rotational bands. These observations were interpreted as band termination.…”