The yrast rotational bands of selenium-74 and krypton-77

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5115775

Gross, C J

New states in the positive parity yrast bands of {sup 74}Se and {sup 77}Kr have been observed with the reactions {sup 52}Cr({sup 28}Si,{alpha}2p){sup 74}Se and {sup 52}Cr ({sup 28}Si,2pn){sup 77}Kr at 98 MeV. The target consisted of approximately 1 mg/cm{sup 2} natural chromium (84% {sup 52}Cr abundance) evaporated on a thick lead backing. The new states extend the known level scheme of {sup 74}Se up to I{sup {pi}} = (22{sup +}) and most of the transitions in the other previously reported bands have been seen. For the states I{sup {pi}} {ge} 6{sup +} the spectrum shows a relatively constant moment of inertia parameter (h{sup 2}/2{Theta}) = 27.8 {plus minus} 0.5 keV. Excited positive parity states up to spin (41/2) have been observed in {sup 77}Kr. {Delta}I = 1 transitions have been identified throughout the positive parity band. The energies, mixing ratios and B(M1) transition rates for these transitions alternate in size as the spin increases. A cranked shell model analysis was performed along with Strutinsky-Bogolyubov cranking calculations. The observed decrease in the signature splitting of the {nu}g{sub 9/2} band has been attributed to a band crossing due to an aligning pair of g{sub 9/2} protons. Prolate quadrupole deformations of {beta}{sub 2} = 0.34 for the ground band and {beta}{sub 2} = 0.26 for the first excited band are predicted. This band crossing is associated with a shape change caused by the polarization effect of aligned quasiparticles.

• Research Organization: Florida State Univ., Tallahassee, FL (USA)
• OSTI ID: 5115775
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400000* -- Chemistry
645100 -- High Energy Physics-- Particle Interactions & Properties-Experimental
651620 -- Nuclear Properties & Reactions
A=59-89
Experimental
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CALCULATION METHODS
CHROMIUM 52 TARGET
DATA
ENERGY LEVELS
ENERGY RANGE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXCITED STATES
EXPERIMENTAL DATA
HOURS LIVING RADIOISOTOPES
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
KRYPTON 77
KRYPTON ISOTOPES
MEASURING INSTRUMENTS
MEASURING METHODS
MEV RANGE
MEV RANGE 10-100
NUCLEI
NUMERICAL DATA
RADIOISOTOPES
ROTATIONAL STATES
SELENIUM 74
SELENIUM ISOTOPES
STABLE ISOTOPES
TARGETS