Feshbach-Kerman-Koonin analysis of [sup 93]Nb reactions: [ital P][r arrow][ital Q] transitions and reduced importance of multistep compound emission

Journal Article · Sat May 01 04:00:00 EDT 1993 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.47.2255· OSTI ID:6874871

Chadwick, M B; Young, P G ^[1]

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1. Nuclear Data Group, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States) Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

We have implemented multistep compound (MSC) and multistep direct (MSD) preequilibrium theories of Feshbach, Kerman, and Koonin (FKK) for the calculation of nucleon-induced reactions. Unlike most previous analyses, which have concentrated on just one of these multistep mechanisms, we consider both mechanisms as well as subsequent Hauser-Feshbach equilibrium emission, and describe the complete nucleon emission spectra and angular distributions quantum mechanically. We compare theoretical calculations of ([ital n],[ital n][prime]) and ([ital n],[ital p]) reactions on [sup 93]Nb at energies of 14, 20, and 25.7 MeV with experimental data. Our analysis suggests that the FKK theory should be modified to allow transitions from the MSD to MSC preequilibrium chains, and shows MSC processes to be less important than previously thought. We find that the MSD mechanism dominates preequilibrium emission even for incident neutron energies as low as 14 MeV. A model to account for preequilibrium flux cascading from the MSD to MSC chain is presented, and we check its validity with a least-squares fit to data which establishes the experimentally observed partitioning between MSD and MSC.

• OSTI ID: 6874871
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 47:5; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

663300* -- Nuclear Reactions & Scattering
General-- (1992-)
663430 -- Nucleon-Induced Reactions & Scattering-- (1992-)
663560 -- Nuclear Mass Ranges-- A=90-149-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
BARYON REACTIONS
COMPOUND NUCLEI
DIRECT REACTIONS
DISTRIBUTION
EMISSION SPECTRA
ENERGY RANGE
HADRON REACTIONS
INELASTIC SCATTERING
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 10-100
NEUTRON REACTIONS
NIOBIUM 93 TARGET
NUCLEAR REACTIONS
NUCLEON REACTIONS
SCATTERING
SPECTRA
STATISTICAL MODELS
TARGETS