Rotational band structure and deformation properties of states in strontium-81
The level structure and lifetimes of excited states in {sup 81}Sr were investigated using the techniques of in beam {gamma} ray spectroscopy. The reactions {sup 56}Fe({sup 28}Si,2pn){sup 81}Sn and {sup 55}Mn({sup 29}Si,p2n){sup 81}Sr were used at beam energies of 103.6 and 95.2 MeV, respectively. The targets consisted of 0.1 mm thick natural Fe (92% {sup 56}Fe abundance) and {approx equal} 2 mg/cm{sup 2} {sup 55}Mn evaporated on a thick lead backing. The previously known level scheme was confirmed and a total of 15 new levels were placed in {sup 81}Sr. Tentative spin assignments were based on level systematics, directional correlations between {gamma} rays and effective level lifetimes. The mean lifetimes of 12 states were measured and lifetime limits were assigned for 10 others using the Doppler shift attenuation method. The deformation properties of states in {sup 81}Sr were determined from the lifetimes and compared to the deformation inferred from level energies. The four rotational band structures in {sup 81}Sr were found to have differing deformations which persist to high spins. The magnitude of this deformation ranges from {beta} {approx equal} 0.2 to {approx equal} 0.4. Band crossings in the moderately deformed g{sub 9/2} yrast and K = 5/2{sup {minus}} bands were observed and a very deformed K = 1/2{sup (+)} band was seen up to a tentative spin of 31/2h. The experimental results were compared to theoretical projected and deformed shell model calculations. The crossing observed in the yrast band has been attributed to the alignment of two g{sub 9/2} protons. The properties of the K = 1/2{sup (+)} band are shown to be consistent with a configuration based on a d{sub 5/2} intruder orbital. This is the first nucleus in the mass 80 region to exhibit such a strongly deformed band based on this configuration.
- Research Organization:
- Florida State Univ., Tallahassee, FL (USA)
- OSTI ID:
- 5065760
- Country of Publication:
- United States
- Language:
- English
Similar Records
Proton and neutron alignments and transition strengths in the transitional nucleus /sup 81/Rb
High-spin states and shape change in /sup 81/Sr
Related Subjects
400101* -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
651620 -- Nuclear Properties & Reactions
A=59-89
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALINE EARTH ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
DATA
ENERGY LEVELS
ENERGY RANGE
EVEN-ODD NUCLEI
EXCITED STATES
EXPERIMENTAL DATA
GAMMA SPECTROSCOPY
INFORMATION
INTERMEDIATE MASS NUCLEI
IRON 56 TARGET
ISOTOPES
LIFETIME
MANGANESE 55 TARGET
MEASURING INSTRUMENTS
MEASURING METHODS
MEV RANGE
MEV RANGE 10-100
MEV RANGE 100-1000
MINUTES LIVING RADIOISOTOPES
NUCLEI
NUMERICAL DATA
RADIOISOTOPES
SPECTROSCOPY
STRONTIUM 81
STRONTIUM ISOTOPES
TARGETS