Rotation-aligned isomer and oblate collectivity inPt196

Abstract

An oblate rotational sequence, built on an aligned, two-quasineutron isomeric state has been established in 196 Pt. The isomer has a half-life of 7.7(7) ns and is associated with the I π =12 + , (i 13/2 ) 2 neutron configuration. Excited states, with angular momentum generated primarily through successive nucleon alignments, have been populated through 1p transfer from 197 Au. The nucleus 196 Pt is the most neutron-rich Pt isotope for which high-spin states, beyond the 12 + isomeric state, have been established thus far. Cranked shell model calculations have been performed to understand shape evolution with spin, and the role of nucleons occupying specific Nilsson orbitals in generating aligned angular momentum for both prolate and oblate deformations has been explored.

Isomers from intrinsic excitations in Tl200 and Pb201,202

“…Details about the analysis are found in Refs. [12,13]. The software packages RADWARE [14] and TSCAN [15] were utilized in the data analysis.…”

“…The half-life of 4.8(2) ns previously measured for the 1244-keV state [2] was revisited in the present work using the centroid-shift technique [12,13]. The difference in time of γ rays above this level (311 and 230 keV) and the 490-keV transition deexciting it were plotted and compared with those obtained for two prompt transitions of similar energies (Fig.…”

Structure of odd- A Pt isotopes along the line of stability

“…Various multi-dimensional energy and time histograms were created and analyzed to establish the level structure and lifetimes of isomeric states, in addition to the multipolarities of observed transitions. Details about the data analysis may be found elsewhere [2,3].…”

“…The structure of nuclei in the A≈190-200 region exhibits a complex interplay between collective effects and those due to individual nucleons. These nuclei show evidence of moderate deformation and excited states appear to result from collective rotation [1][2][3]. However, owing to the small number of valence nucleons, collectivity is not as well developed as, for example, in the deformed, mid-shell A≈170-180 region.…”

In-beam γ -ray spectroscopy of the neutron-rich platinum isotope Pt200 toward the N=126 shell gap

“…While the less neutron-rich stable platinum isotopes were studied up to high spin via heavy-ion [18,19] and (α, xn) [20][21][22][23][24][25][26] and stable beam-target combinations. Multinucleon-transfer reactions are complementary to fusion-evaporation reactions and have been used to study medium-to-high spin states in the 194,196,198 Pt isotopes [27][28][29][30]. Besides multinucleon transfer reactions, neutron-rich platinum isotopes were also studied via isomeric-decay spectroscopy after the fragmentation of a 208 Pb beam at relativistic energies.…”