I. Core-quasiparticle coupling model calculations as a test of IBA core descriptions of the even-mass Hg isotopes. II. Decay of mass-separated /sup 203/At

Technical Report · Mon Jul 01 04:00:00 EDT 1985

OSTI ID:5439276

Semmes, P B

The Core-Quasiparticle Coupling Model (CQCM) for odd-mass nuclei, which is based on dynamical field theory and the Bardeen-Cooper-Schrieffer (BCS) method, has been applied to two problems. In the first, a study of Pauli exchange effects for the odd particle in the Interacting Boson-Fermion Model (IBFM) is made by a comparison with the CQCM. Spectra for a partly filled j-shell coupled to Interacting Boson Model cores are calculated in both models, and values of the IBFM exchange parameter ..lambda../sub 0/ are found which lead to spectra similar to those in the CQCM. In the second application, CQCM calculations have been performed for the i/sub 13/2/ bands in the odd-mass Hg isotopes, h/sub 9/2/ bands in the odd-mass Tl isotopes, and the h/sub 11/2/ bands in the odd-mass Au isotopes (A = 189 to 195). The even-mass Hg core descriptions were taken from previous proton-neutron Interacting Boson Model (IBM-2) calculations, and thus a comparison between the experimental and calculated level schemes for the odd-mass isotopes can be interpreted as a test of the core description. A predicted transition from positive Q(2/sup +/) near A = 195 to negative Q(2/sup +/) near A = 191 is not borne out by the odd-mass data. The radioactive decay of /sup 203/At to /sup 203/Po has been studied with mass-separated sources from the UNISOR facility. Time-sequenced spectra of ..gamma..-rays, x-rays, and conversion electrons have been obtained, together with ..gamma..-..gamma..-t, ..gamma..-X-t, e/sup -/-..gamma..-t and e/sup -/-X-t coincidence data. From this information, a decay scheme has been constructed, consisting of 30 excited states and 45 transitions that incorporate approximately 90% of the decay intensity assigned to /sup 203/At. All excited states below 1 MeV have been assigned unique spin-parity values, and the observed level scheme can be qualitatively understood in terms of a particle-core weak coupling description. The ground-state decay energy has been deduced.

• Research Organization: Georgia Inst. of Tech., Atlanta (USA)
• DOE Contract Number: AS05-76ER03346
• OSTI ID: 5439276
• Report Number(s): DOE/ER/03346-264; ORO-3346-264; ON: DE85016956
• Country of Publication: United States
• Language: English

Related Subjects

651913* -- Nuclear Properties & Reactions
A=190-219
Theoretical-- Energy Levels & Transitions-- (-1987)
651922 -- Nuclear Properties & Reactions
A=190-219
Experimental-- Radioactive Decay-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA DECAY RADIOISOTOPES
ASTATINE 203
ASTATINE ISOTOPES
BCS THEORY
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
DECAY
ELECTRON CAPTURE RADIOISOTOPES
ENERGY LEVELS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXCITED STATES
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
INTERACTING BOSON MODEL
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MATHEMATICAL MODELS
MERCURY 186
MERCURY 188
MERCURY 189
MERCURY 190
MERCURY 191
MERCURY 192
MERCURY 193
MERCURY 194
MERCURY 195
MERCURY 196
MERCURY 197
MERCURY 198
MERCURY ISOTOPES
MINUTES LIVING RADIOISOTOPES
NUCLEAR MODELS
NUCLEI
ODD-EVEN NUCLEI
POLONIUM 203
POLONIUM ISOTOPES
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
SHELL MODELS
STABLE ISOTOPES