Triaxial deformation and nuclear shape transition in192Au

Abstract

Background : Nuclei in A ≈ 190 mass region show gradual shape changes from prolate through non-axial deformed shapes and ultimately towards spherical shapes as the Pb region is approached. Exploring how this shape evolution occurs will help understand the evolution of collectivity in this region. Purpose : The level scheme of the 192 Au nucleus in A ≈ 190 region was studied in order to deduce its deformations. Methods : High-spin states of 192 Au have been populated in the 186 W( 11 B, 5n) reaction at a beam energy of 68 MeV and their γ decay was studied using the YRAST Ball detector array at the WNSL, Yale University. Results : Based on double and triple γ-ray coincidence data the level scheme of 192 Au has been extended up to I π = 32 + at an excitation energy of ∼ 6 MeV. Conclusion : The results are discussed in the framework of pairing and deformation self-consistent Total Routhian Surface (TRS) and Cranked Shell Model (CSM) calculations. The comparison of the experimental observations with the calculations indicates that this nucleus takes non-axial shape similar to other Au nuclei in this region.

γ-ray spectroscopy of low-lying excited states and shape competition inOs194

“…Assuming axial symmetry, the extracted half-life of the yrast 2 + state in 194 Os can be used to determine a value for the effective quadrupole deformation parameter (see Table II) using equation 1 [45,46], which relates the B(E2 : 0 + → 2 + ) to the β 2 deformation parameter [47][48][49]. This can then be related to the effective quadrupole deformation parameter β eff through the use of shape invariants [50] to the B(E2 : 0 + → 2 + ) value by…”

Breaking of axial symmetry in excited heavy nuclei as identified in giant dipole resonance data

“…The ongoing discussion [1][2][3][4] about triaxial shapes in heavy nuclei, recently often studied off stability, may provoke the question, how well the widely used assumption about axial symmetry of most less exotic nuclei is founded on sufficiently sensitive experimental data. A nonaxial shape of heavy nuclei is a less stringent assumption than the often made assumption of axiality, which probably originates from atomic hyperfine structure observations [5], which are usually made on unpolarized samples and thus are insensitive to broken axiality.…”