Quasiparticle nature of rotational bands inPt185

Abstract

High-spin states in '"Pt have been studied with the ' Yb(' 0,4n }'"Pt reaction at 90 MeV using a multidetector array consisting of five Ge detectors and a multiplicity filter of six NaI counters. Rotational bands built on the Nilsson configurations -+[624], -[503], and -' [521] have been identified and interpreted within the framework of'the cranked shell model. Additional band structures built on levels at 3.131 and 3.294 MeV are observed which arise from more complex configurations. Experimental values of B(M1;I~I -1 }/B(E2;I~E -2} ratios have been extracted and compared to predictions of the semiclassical Donau and Frauendorf approach.

Properties of the ν7/2 − [503]( f 7/2 ) band in 185 Pt

“…Furthermore, compared with the level scheme in Ref. [4], transitions between the two signatures above the 237.6 keV γ ray were not observed in the present experiment and the observed intensities have necessitated a reordering of the earlier reported sequences. Consequently, we interchanged the ordering of the 495.5 and 501.…”

“…The spins and parities for the known low-lying states were adopted from the previous work [6], and these values were used as references for the spin and parity assignments of the higher spin states. Prior to this work, the two signatures were known up to 27/2 − and 29/2 − states, respectively [4]. In the present study, one signature was extended to the 35/2 − state and the other one was extended to a tentative state of 33/2 − .…”

“…The present work aims at extending the level scheme of 185 Pt to higher spin states via heavy-ion induced reactions and studying the structural properties of the negative-parity band. Prior to the present work, high-spin states of 185 Pt were reported in the literature [4].…”

High-spin structure in 187Pt

“…In order to explain the large signature splitting in the νi 13/2 band, a mechanism leading to enhanced mixing with an Ω = 1/2 orbit is needed. In the lighter odd-A Pt nuclei [16,22,25] , large signature splitting was also observed in the νi 13/2 bands. It was proposed that it is the negative values of γ and β 4 that cause this phenomenon [16,22] .…”

“…We deduced the decoupling parameter α from the excitation energies of the levels with spins of 5/2, 9/2, and 13/2 for the concerned decoupled bands. Band 5 has a negative α value of −2.4, and this can be compared with α = α1.2 and −0.7 for the ν1/2 − [521] bands in 183 Pt and 185 Pt [22,25] , respectively. On the other hand, the decoupling parameter α has positive valves of 0.8 and 0.5 for the ν1/2 − [510] bands in the isotones 185 Os and 183 W [17,24] .…”