Preequilibrium spin effects in Feshbach-Kerman-Koonin and exciton models and application to high-spin isomer production
- University of California, Nuclear Data Group, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States) University of California, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) Nuclear Data Section, International Atomic Energy Agency, Vienna (Austria) Soltan Institute for Nuclear Studies, 00-681 Warsaw (Poland)
We describe how the Feshbach-Kerman-Koonin (FKK) theory can be used to obtain residual nucleus spin distributions following preequilibrium decay, by removing the assumption of zero intrinsic spins in multistep direct reactions. By making use of parallels between the exciton model and the FKK multistep direct theory we also obtain a straightforward method for determining spin distributions in the exciton model. We compare these two approaches and apply them to high-spin isomer production cross sections in 14 MeV neutron reactions on hafnium. We obtain reasonable agreement with measurements, though there is evidence that the FKK theory underpredicts high spin transfer reactions. Comparisions with the exciton model suggest that multistep processes in FKK are underestimated, and that an FKK formulation incorporating non-normal DWBA transitions may yield results in closer agreement with the exciton model, and with experiment.
- OSTI ID:
- 7238878
- Journal Information:
- Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 49:6; ISSN 0556-2813; ISSN PRVCAN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
General-- (1992-)
663430 -- Nucleon-Induced Reactions & Scattering-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON REACTIONS
CROSS SECTIONS
DIRECT REACTIONS
ENERGY LEVELS
ENERGY RANGE
EXCITON MODEL
FLUCTUATIONS
HADRON REACTIONS
HAFNIUM 179 TARGET
HIGH SPIN STATES
INELASTIC SCATTERING
ISOMERIC NUCLEI
ISOMERS
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 10-100
NEUTRON REACTIONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
SCATTERING
TARGETS
VARIATIONS