Nuclear Orientation Studies of Isotopes Far from Stability.
Abstract
Available from UMI in association with The British Library. Requires signed TDF. Low Temperature Nuclear Orientation (LTNO) is an important technique in the study of nuclei far from stability. The theory of LTNO and its applications to the measurement of static nuclear moments and other quantities of spectroscopic interest are reviewed. Among the nuclei off the line of stability those in the A ~ 75 region are of considerable interest, exhibiting large quadrupole deformations, triaxiality and shape coexistence. LTNO measurements performed on neutron deficient bromine isotopes have yielded the static magnetic dipole moments of the nuclei ^ {72g,72m,74m,75,76,77}Br, spectroscopic information on ^{7277}Se and also identified the ground state spin of ^ {73}Br as 1/2^. Existing odd A and oddodd particlerotor computer codes have been extended in order to include a Variable Moment of Inertia (VMI) asymmetric rotational core. The formalism necessary for this modification is developed. The measured magnetic moments are interpreted within the framework of this particleVMI rotor model. It is shown that the systematic reduction in the moments of the odd A nuclei ^{7581}Br characterizes the transformation of the prolate ground state configuration from largely pi (301) 3/2 in ^{79,81}Br to almost pure pi (312) 3/2 in ^{75,77}Br. This trend is fully consistent with the increase in deformation towards the lower masses suggested by the known electric quadrupole moments. In contrast, the ground state spin of ^{73}Br can only be interpreted in terms of an oblate nuclear shape. This is the first evidence for the predicted prolateoblate shape transition in the bromine nuclei. In addition the magnetic moment of ^{74}BrR^ {m}, by identifying a pi (431) 3/2nu (422) 5/2 configuration, strongly suggests a positive parity assignment for the isomeric state. Finally, an experiment to search for possible Tviolation effects in nuclear gamma decay is described. Using coincidence techniques, a measurement of the Todd Peven quantity (I cdot k times e)(I cdot k)(I cdot e) has lead to a limit on the Tviolating phase angle between the E2 and M1 matrix elements associated with the 604 keV gamma transition in ^{192 }Pt of sin eta = +/11(12) times 10 ^{3}.
 Publication:

Ph.D. Thesis
 Pub Date:
 1989
 Bibcode:
 1989PhDT.......124G
 Keywords:

 Physics: Nuclear