Preequilibrium decay of nuclei with A approx. = 90 at excitation energies to 100 MeV
Calculations have been made of the excitation functions of 28 nuclear reactions induced by 10--100 MeV protons incident upon targets in the mass region, A = 90. Eleven of these reactions have mechanistic components arising from the emission of ..cap alpha.. particles. Similar calculations have been made of the proton and ..cap alpha.. particle spectra for 62 MeV protons incident on /sup 89/Y. The results of all of the calculations have been compared with the appropriate experimental data. The calculations utilize the theoretical framework of the preequilibrium exciton model for nuclear reactions in conjunction with conventional evaporation theory. A number of recent advances in the computation of equilibration and emission rates, state densities, and the nucleon mean free path have all been incorporated. In addition, introduction of a preformation factor allows the inclusion of ..cap alpha.. particle emission in both the preequilibrium and evaporation stages of the calculation. Agreement between the calculations making use of no freely varying parameters and all of the experimental data is excellent. In particular, the theoretical model has reproduced the excitation functions for both simple (p,n) and complex (p,4p6n) reactions, at proton energies varying over nearly 100 MeV, for peak cross sections of as little as 1 mb to as great as 1000 mb, including the reactions showing the characteristic double himped curve indicative of ..cap alpha.. particle emission. Equally well reproduced are the differential proton and ..cap alpha.. particle energy spectra. The characteristics of the reaction model are discussed with particular reference to the consequences of the more recent advances in the theory mentioned above.
- Research Organization:
- Instituto di Fisica dell'Universita di Milano, Milano, Italia
- OSTI ID:
- 5234299
- Journal Information:
- Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 16:4; ISSN PRVCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
A=59-89
Theoretical-- Nuclear Reactions & Scattering-- (-1987)
651715 -- Nuclear Properties & Reactions
A=90-149
Theoretical-- Nuclear Reactions & Scattering-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA SPECTRA
BARYON REACTIONS
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DECAY
ENERGY RANGE
ENERGY SPECTRA
EVAPORATION MODEL
EXCITATION FUNCTIONS
HADRON REACTIONS
MATHEMATICAL MODELS
MATRIX ELEMENTS
MEV RANGE
MEV RANGE 10-100
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEON REACTIONS
PRECOMPOUND-NUCLEUS EMISSION
PROTON REACTIONS
PROTON SPECTRA
SPECTRA
STRONTIUM 88 TARGET
TARGETS
YTTRIUM 89 TARGET
ZIRCONIUM 90 TARGET