Deformation in the Neutron-Deficient Rare Earth Isotopes: Radioactive Decay Scheme Studies in the Neodymium, Promethium, and Samarium Isotopes.
Abstract
Several experiments were performed at the UNISOR isotope separator facility at HHIRF at the Oak Ridge National Laboratory on the beta^+/EC decay of neutron-deficient rare earth isotopes. Data for the decay chain ^{133}Sm to ^ {133}Pm to ^{133}Nd was obtained, consisting of multiscaled spectra of gamma rays, X rays, and conversion electrons, as well as gammagammat, Xgamma t, egammat and eXt coincidences. Gamma rays associated with the decay of ^{133 }Sm and ^{133}Pm were observed for the first time. The decay of a new low -spin (1/2) isomeric state, with a half life of about 70 sec was established for ^{133} Nd. The level schemes for ^{133 }Nd and ^{133}Pr were constructed. An M3 and two E1 isomers are established in ^{133}Nd and an E3 isomer is confirmed in ^{133} Pr. The energy level systematics for the nuclear region bounded by Z >= 58 and N <= 78 is discussed. Theoretical interpretations are based on the particle-plus-triaxial rotor model calculations. In the framework of these calculations, the beta _2 deformation is moderate for these nuclei (beta_2 ~ 0.20-0.25). A sudden onset of strong deformation is not observed, in contrast with the theoretical predictions by Leander and Moller (Lea82).
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1993
- Bibcode:
- 1993PhDT.......163B
- Keywords:
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- Physics: Nuclear