Light charged particles and intermediate mass fragments from the reactions 486, 550, 640, and 730 MeV [sup 86]Kr + [sup 63]Cu

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5503543

Boger, J T

A study has been made of the reaction [sup 86]Kr + [sup 63]Cu at incident energies of 486, 550, 640, and 730 MeV. Measurements include cross sections, angular distributions, and energy spectra for light charged particles ([sup 1,2,3]H and [sup 4]He), intermediate mass fragments (IMF) (4 [le] Z [le] 17), and heavy fragments (Z [ge] 18). Coincidences between light charged particles and between particles and fragments have been measured to obtain cross sections, energy spectra, and angular distributions. Statistical model analysis of the energy spectra for [sup 1]H and [sup 4]He detected in coincidence with the fragments has allowed estimation of [sup 1]H and [sup 4]He multiplicities associated with the evaporation residues, fragments, and composite nuclei prior to scission. A comparison of cross sections, energy spectra, angular distributions, and particle multiplicities for these matched entrance channels has provided the means for a detailed test of the Bohr Independence Hypothesis. Results of this comparison indicate extensive shape and thermal equilibration of the composite nuclei over the excitation energy range of 128 to 231 MeV. This conclusion is reached even for nuclear systems whose decay lifetimes are expected to be similar to their relaxation times. Three sources for IMF production have been identified: (1) asymmetric binary fission, (2) sequential binary fission, and (3) simultaneous three- (or more) body breakup. Barriers to asymmetric fission and average emitter spins have been extracted from a statistical model analysis of the IMF excitation functions. The barriers are more than 30% larger than those calculated by the Yukawa plus exponential finite range nuclear (YEFRN) model. The average total kinetic energies (TKE) are between values calculated by the YEFRN model for the upper limit and the lower limit. This suggests this model may overestimate nuclear stabilization. A dynamical model may be required for these fissionlike reactions.

• Research Organization: State Univ. of New York, Stony Brook, NY (United States)
• OSTI ID: 5503543
• Country of Publication: United States
• Language: English

Related Subjects

663470* -- Fission-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
BINARY FISSION
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
COPPER 63 REACTIONS
CROSS SECTIONS
DISTRIBUTION
ENERGY RANGE
ENERGY SPECTRA
EXCITATION FUNCTIONS
FISSION
FUNCTIONS
HEAVY ION REACTIONS
KRYPTON 86 REACTIONS
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 100-1000
NUCLEAR REACTIONS
SPECTRA
STATISTICAL MODELS