Studies of sup 4 He/ sup 1 H emission in fission and deeply inelastic reactions of 485-MeV sup 56 Fe with sup 197 Au

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5124408

Moses, D J

Emission of {sup 4}He and {sup 1}H has been studied in reactions of 485-MeV {sup 56}Fe + {sup 197}Au. The light charged particles were measured both in singles and in coincidence with heavy products of deeply inelastic and fission reactions. Experimental detection capabilities were greatly enhanced through the use of two five-detector arrays for light charged particles, and two heavy fragment trigger detectors placed at symmetrically opposite angles with respect to the beam direction. Statistical model analyses of the data show that nearly all {sup 4}He/{sup 1}H intensity is due to evaporation from energy equilibrated reaction products both in deeply inelastic and fission reactions. In deeply inelastic reactions, the observed {sup 4}He/{sup 1}H emission can be attributed to evaporation from the post-scission reactant-like products, while in fusion-like fission reactions {sup 4}He/{sup 1}H evaporation from pre- and post-scission sources are observed in roughly equivalent amounts. Angle-integrated multiplicities for {sup 4}He and {sup 1}H are deduced for each source of emission, and are compared with results from similar systems. The {sup 4}He/{sup 1}H multiplicity ratios show no strong dependence on emitter spin, in contrast to simple expectations. Particle evaporation times are evaluated semi-quantitatively, based on relationships between estimated emitter lifetimes and experimental observations, and are compared to other characteristic timescales. Apparent reductions in {sup 4}He evaporation barriers can be explained by shape deformation of the composite system in fusion-like reactions, but for {sup 1}H emission the barrier lowering is too large to be reasonably characterized in this manner.

• Research Organization: Carnegie-Mellon Univ., Pittsburgh, PA (USA)
• OSTI ID: 5124408
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
DATA
DATA ANALYSIS
ENERGY RANGE
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FISSION FRAGMENTS
GOLD 197
GOLD ISOTOPES
HEAVY NUCLEI
HELIUM ISOTOPES
HYDROGEN ISOTOPES
INELASTIC SCATTERING
INFORMATION
INTERMEDIATE MASS NUCLEI
IRON 56
IRON ISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MEASURING INSTRUMENTS
MEASURING METHODS
MEV RANGE
MEV RANGE 100-1000
NUCLEAR FRAGMENTS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
RADIOISOTOPES
SCATTERING
SECONDS LIVING RADIOISOTOPES
STABLE ISOTOPES