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Title: Neutron-multiplicity distributions for (. cap alpha. ,xn. gamma. ) reactions with E/sub. cap alpha. / = 50--120 MeV and the pre-equilibrium neutron deexcitation processes

Pre-equilibrium and equilibrium deexcitation processes for (..cap alpha..,xn ..gamma..) reactions induced by 50--120 MeV ..cap alpha.. particles were studied. Reaction channels were identified by measuring rotational ..gamma.. rays characteristic of the reaction residues. The branching of the reaction channels gave neutron multiplicity distributions. Features characteristic of the pre-equilibrium process were seen in the reaction channels with small neutron multiplicity x. An exciton model calculation code was developed so as to incorporate both multiparticle emission at the fast pre-equilibrium stage and multiparticle p evaporation at the slow equilibrium stage. The calculation reproduced the neutron multiplicity distributions in the whole range of E/sub ..cap alpha../ = 50--120 MeV. The pre-equilibrium fractions and the entry lines from the pre-equilibrium stage to the equilibrium one were deduced. The pre-equilibrium fractions were found to be approximately 40--60 %, being rather independent of the individual reaction channel. The entry lines slowly increase from 25 to 35 MeV with increasing projectile energy.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
5650361
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. C; (United States); Journal Volume: 28:2
Research Org:
Department of Physics, Osaka University, Toyonaka, Osaka 560, Japan
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALPHA REACTIONS; PRECOMPOUND-NUCLEUS EMISSION; DYSPROSIUM 162 TARGET; DYSPROSIUM 164 TARGET; YTTERBIUM 174 TARGET; YTTERBIUM 176 TARGET; COMPOUND-NUCLEUS REACTIONS; CROSS SECTIONS; ERBIUM ISOTOPES; EXCITON MODEL; EXPERIMENTAL DATA; GAMMA RADIATION; HAFNIUM ISOTOPES; MEV RANGE 10-100; MEV RANGE 100-1000; MULTIPLICITY; NEUTRONS; BARYONS; CHARGED-PARTICLE REACTIONS; DATA; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; ENERGY RANGE; FERMIONS; HADRONS; INFORMATION; IONIZING RADIATIONS; ISOTOPES; MATHEMATICAL MODELS; MEV RANGE; NUCLEAR MODELS; NUCLEAR REACTIONS; NUCLEONS; NUMERICAL DATA; RADIATIONS; RARE EARTH ISOTOPES; TARGETS 651825* -- Nuclear Properties & Reactions, A=150-189, Experimental-- Nuclear Reactions & Scattering-- (-1987)