Time scales for binary fragmentations of highly excited, fissile nuclei from sup 32 S+ sup 197 Au, sup 232 Th

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Physical Review, C (Nuclear Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevC.43.716· OSTI ID:5845112

Mordhorst, E; Strecker, M; Frobeen, H; Gasthuber, M; Scobel, W ^[1]; Gebauer, B; Hilscher, D; Lehmann, M; Rossner, H; Wilpert, T ^[2]

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1. Universitaet Hamburg, I. Institut fuer Experimentalphysik, D-2000 Hamburg 50, Federal Republic of Germany (DE)
2. Hahn-Meitner-Institut Berlin, D-1000 Berlin 39 (Federal Republic of Germany)

Fission of {sup 197}Au,{sup 232}Th+838-MeV {sup 32}S projectiles was studied by measuring fragment coincident neutrons. Neutron energy spectra were decomposed into preequilibrium, prescission, and postscission contributions with a constrained moving source analysis. Excitation energies deduced from the transferred linear momentum are consistent with calculations applying the Boltzmann master equation, and with an energy balance based upon the experimental neutron multiplicities and charged particles from evaporation calculations. The time scale of fission derived from the prescission neutron multiplicities extends from 5{times}10{sup {minus}21} to 3{times}10{sup {minus}20} s; it does not depend on the initial excitation energy, is about a factor of 2 longer for symmetric than for asymmetric fragmentations, and increases with the fissility of the primary reaction system. For all mass splits, the excitation energy left at scission is 50--60 MeV.

• OSTI ID: 5845112
• Journal Information: Physical Review, C (Nuclear Physics); (USA), Journal Name: Physical Review, C (Nuclear Physics); (USA) Vol. 43:2; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BOLTZMANN EQUATION
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
COINCIDENCE SPECTROMETRY
COMPOUND-NUCLEUS REACTIONS
DETECTION
DIFFERENTIAL EQUATIONS
EMISSION
ENERGY BALANCE
ENERGY RANGE
ENERGY SPECTRA
EQUATIONS
FISSION
FISSION FRAGMENT DETECTION
GOLD 197 TARGET
HEAVY ION REACTIONS
MASS SPECTRA
MEV RANGE
MEV RANGE 100-1000
MOMENTUM TRANSFER
MULTIPLICITY
NEUTRON EMISSION
NUCLEAR REACTIONS
PARTIAL DIFFERENTIAL EQUATIONS
RADIATION DETECTION
SPECTRA
SULFUR 32 REACTIONS
TARGETS
THORIUM 232 TARGET