Search for reflection asymmetry in medium-mass nuclei: a study of the structure of /sup 145/Ba, /sup 147/Ce, /sup 143/Ba, and /sup 139/Xe

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6057116

Robertson, J D

A detailed study of the structures of /sup 145/Ba, isotopic /sup 143/Ba, isotonic /sup 147/Ce, and N = 85 /sup 139/Xe were undertaken to test the hypothesis that reflection asymmetric structures are a necessary ingredient of an accurate description of the low-lying levels in the A = 145 neutron rich region. The decay studies were performed at the TRISTAN mass separator which is on-line to the High Flux Beam Reactor at Brookhaven National Laboratory. The studies involved ..gamma..-singles, ..gamma..-..gamma.. coincidence, ..gamma..-..gamma.. angular correlation, and internal conversion electron measurements. Spins and parities have been assigned to the low-lying levels in the Ba isotopes based upon the angular correlation coefficients and the internal conversion coefficients. Tentative spin and parity values have been assigned to the levels in /sup 139/Xe and /sup 147/Ce from the observed ..gamma..-ray branching and the systematics of the N = 85 and N = 89 isotones. The octupole deformed rotational structure which marks the light odd-A actinides is not observed in /sup 145/Ba, /sup 147/Ce, or /sup 143/Ba. The structure of /sup 139/Xe with only three neutrons beyond the closed shell at N = 82 can be described in terms of the cluster-vibration model as an f/sub 7/2//sup 3/ cluster coupled to the N = 82 core. The three transitional nuclei, however, can not be consistently described either in terms of the shell model (as a cluster) or in terms of the standard quadrupole deformed Nilsson model. This fact, coupled with the large structure change that occurs between N = 85 and N = 87, suggests that higher orders of deformation (including ..beta../sub 3/) may account for the structure observed in /sup 143/Ba, /sup 145/Ba and /sup 147/Ce.

• Research Organization: Maryland Univ., College Park (USA)
• OSTI ID: 6057116
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ALKALINE EARTH ISOTOPES
ANGULAR CORRELATION
BARIUM 143
BARIUM 145
BARIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CERIUM 147
CERIUM ISOTOPES
CONVERSION
CORRELATIONS
DECAY
ELECTRONIC STRUCTURE
ELECTRONS
ELEMENTARY PARTICLES
EVEN-ODD NUCLEI
FERMIONS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION
ISOTOPES
LEPTONS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
SECONDS LIVING RADIOISOTOPES
XENON 139
XENON ISOTOPES