Tri-axial Shape Coexistence and a New Aligned Band in {sup 178}Os
- Department of Physics, Panjab University, Chandigarh-160014 (India)
The Os nuclei lie in the beginning of the transitional region between the well deformed rare earth and spherical lead isotopes. The nuclei in this region are believed to be soft to changes in gamma deformation due to the softness of nuclear potential which may result in the shape coexistence. The neutron Fermi levels in Os nuclei from A = 170 to A = 186 lie in the middle of i{sub 13/2} orbital so that their shape in the ground state tends to take an appreciable prolate deformation. Hence collective bands with the well defined moment of inertia occur and the effect of different proton orbitals is observed as a modulation of the prolate structure. The anomalies in the yrast sequence, an effect attributed to change in moment of inertia of the ground state rotational band and the band crossing phenomena, are very important and vary strongly with neutron number in case of Os nuclei. The nuclear structure of {sup 178}Os nucleus has been studied using the reaction {sup 165}Ho({sup 20}Ne, p6n){sup 178}Os. Indian National Gamma Array (INGA) consisting of six Clover detectors with anti Compton shields was used for the detection of resulting gamma rays. The Direction Correlation of {gamma}-rays de-exciting Oriented states (DCO) ratio and polarization of gamma rays were measured to assign spin, parity and multipolarity of transitions. Twenty one new transitions belonging to the {sup 178}Os nucleus have been identified. The sudden and rather strong gain in aligned angular momentum is observed in the yrast band of {sup 178}Os. A new aligned rotational band similar to {sup 180}Os is also discovered in this nucleus. This band exhibits a very complex decay pattern with a single linking transition of 1778 keV to the ground state band. The tri-axial shape co-existence is also observed in this nucleus at higher excitation. The experimental results are compared with the Microscopic Hartree-Fock model calculations.
- OSTI ID:
- 21289651
- Journal Information:
- AIP Conference Proceedings, Vol. 1099, Issue 1; Conference: CAARI 2008: 12. international conference on application of accelerators in research and industry, Fort Worth, TX (United States), 10-15 Aug 2008; Other Information: DOI: 10.1063/1.3120157; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COMPARATIVE EVALUATIONS
CORRELATIONS
EXCITATION
FERMI LEVEL
GAMMA DETECTION
GROUND STATES
HARTREE-FOCK METHOD
HIGH-PURITY GE DETECTORS
HOLMIUM 165 TARGET
KEV RANGE
MULTIPOLARITY
NEON 20 REACTIONS
NUCLEAR POTENTIAL
NUCLEAR STRUCTURE
OSMIUM 178
POLARIZATION
ROTATIONAL STATES