Energy equilibration in composite nuclei at high energy and spin: Correlations between evaporative /sup 1/H, /sup 4/He, and fission

Journal Article · Sat May 01 04:00:00 EDT 1982 · Phys. Rev. C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.25.2430· OSTI ID:5019792

Rivet, M F; Logan, D; Alexander, J M; Guerreau, D; Duek, E; Zisman, M S; Kaplan, M

Correlations have been studied between evaporative H/He emission and fissionlike products for the reactions 333 MeV /sup 40/Ar+/sup 116/Sn, /sup 154/Sm, and /sup 197/Au. Fission products were detected at 60/sup 0/ and 320/sup 0/ in coincidence with H and He at 120/sup 0/ in plane and 27/sup 0/ and 60/sup 0/ out of plane. The coincidence energy spectra of H and He are not consistent with evaporation from the moving fragments. An analysis has been made with the assumption of complete energy equilibration in the particle emission (i.e., evaporation) prior to scission. The rather large data set is essentially consistent with this assumption. From the spectral shapes one can deduce level density parameters and barriers to evaporation. Values inferred for the Fermi gas level density parameters are similar to those inferred from experiments at much lower energies. Values deduced for the emission barriers are much smaller than those from systematics of fusion barriers. The observed cross sections for fission and /sup 1/H and /sup 4/He evaporation are not easily reconciled with statistical model calculations. In particular, the proton evaporation seems to compete more favorably with fission and /sup 4/He evaporation than implied by phase space considerations alone.

• Research Organization: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
• OSTI ID: 5019792
• Journal Information: Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 25:5; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ANGULAR CORRELATION
ARGON 40 REACTIONS
BARYONS
CHARGED-PARTICLE REACTIONS
COINCIDENCE SPECTROMETRY
COMPOSITE MODELS
CORRELATIONS
ELEMENTARY PARTICLES
ENERGY DEPENDENCE
ENERGY RANGE
EVAPORATION MODEL
EVEN-EVEN NUCLEI
FERMIONS
FISSION
GOLD 197 TARGET
HADRONS
HEAVY ION ACCELERATORS
HEAVY ION REACTIONS
HELIUM 4
HELIUM ISOTOPES
HILACS
ISOTOPES
LIGHT NUCLEI
LINEAR ACCELERATORS
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 100-1000
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
PARTICLE MODELS
PROTONS
SAMARIUM 154 TARGET
STABLE ISOTOPES
STATISTICAL MODELS
SUPERHILAC
TARGETS
TIN 116 TARGET