Influence of pre-fission particle emission on fragment angular distributions studied for sup 208 Pb( sup 16 O, f )

Journal Article · Sat Feb 01 00:00:00 EST 1992 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.45.719· OSTI ID:7234684

Rossner, H ^[1]; Hinde, D J; Leigh, J R; Lestone, J P; Newton, J O; Wei, J X; Elfstroem, S ^[2]

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1. Hahn-Meitner-Institut Berlin, D-1000 Berlin 39 (Germany)
2. Department of Nuclear Physics, Research School of Physical Sciences, Australian National University, P.O. Box 4, Canberra, ACT 2601 (Australia)

Neutrons have been measured in coincidence with fission fragments of the reaction {sup 208}Pb({sup 16}O,{ital f}) at bombarding energies ranging between 80 and 130 MeV. Pre-scission and post-scission multiplicities were deduced from the neutron spectra by application of a moving source fit procedure. Particles evaporated before the saddle point configuration of the fissioning nucleus will reduce the nuclear temperature of the transition nucleus. This effect of higher chance fission increases the anisotropies of fission fragment angular distributions compared to the assumption of first chance fission. Compound nuclei with nuclear temperatures considerably smaller than the fission barrier have statistical fission decay times that are much longer than saddle-to-scission times. With these conditions it is plausible that most of the particles evaporated from the fissioning nucleus are emitted before the saddle. Fission fragment angular distributions for {sup 208}Pb({sup 16}O,{ital f}) analyzed with the transition state model including the nuclear temperature reduction caused by pre-fission particle emission show normal'' anisotropies at low and near barrier energies.

• OSTI ID: 7234684
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Vol. 45:2; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
LEAD 208 TARGET
OXYGEN 16 REACTIONS
FISSION SPECTRA
ANGULAR DISTRIBUTION
ANISOTROPY
COINCIDENCE METHODS
COMPOUND-NUCLEUS REACTIONS
EXPERIMENTAL DATA
HEAVY ION REACTIONS
MEV RANGE 10-100
MEV RANGE 100-1000
NEUTRON SPECTRA
CHARGED-PARTICLE REACTIONS
COUNTING TECHNIQUES
DATA
DISTRIBUTION
ENERGY RANGE
INFORMATION
MEV RANGE
NUCLEAR REACTIONS
NUMERICAL DATA
SPECTRA
TARGETS
663450* - Heavy-Ion-Induced Reactions & Scattering- (1992-)
663580 - Nuclear Mass Ranges- A=190-219- (1992-)