Entrance and exit channel phenomena in d- and /sup 3/He-induced preequilibrium decay

Journal Article · Wed Oct 01 00:00:00 EDT 1980 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.22.1468· OSTI ID:5119202

Bissem, H H; Georgi, R; Scobel, W; Ernst, J; Kaba, M; Rama Rao, J; Strohe, H

Activation techniques were used to measure more than 30 excitation functions for single and multiple nucleon and/or ..cap alpha.. particle emission for d+/sup 64,66/Zn, /sup 89/Y with E/sub d/=9--26 MeV and /sup 3/He+/sup 63,65/Cu, /sup 93/Nb with E(/sup 3/He)=10--44 MeV. The excitation functions are generally in agreement with the results of a combined equilibrium and pre-equilibrium hybrid model calculation applying initial exciton numbers n/sub 0/=3 for d and n/sub 0/=4 for /sup 3/He reactions. The composite system /sup 66/Ga has been produced via d+/sup 64/Zn and /sup 3/He+/sup 63/Cu at excitation energies between 22 and 36 MeV. An entrance channel dependence shows up in the yields for single p- and n-emission when compared in the double ratio R=sigma(/sup 3/He,p)/sigma(/sup 3/He,n))/(sigma(d,p)/sigma(d,n)). It approaches a value of about 2, indicating enhanced p emission for the /sup 3/He-induced reaction. This value disagrees with the equilibrium isospin formalism and is best reproduced by initial particle exciton numbers np-italic=n/sub 0n/=1.5 for d and n/sub 0p/=2.5, n/sub 0n/=1.5 for /sup 3/He projectiles, indicating conservation of charge asymmetry in the entrance channel. Isomeric ratios have been measured for /sup 89/Y(d,2n)/sup 89/Zr and /sup 93/Nb(/sup 3/He,xn)/sup 96en-dashx/Tc (x=1,2,3). Calculations with a full statistical model fail to reproduce sigma/sub g//sigma/sub m/ as well as sigma/sub g/ and sigma/sub m/ for reasonable values of the spin cutoff parameter. Inclusion of a pre-equilibrium decay mode improves the fit, in particular if the angular momentum depletion of the composite system due to pre-equilibrium decay is increased over that of the equilibrium decay at the same channel energy.

• Research Organization: I. Institut fuer Experimentalphysik, Universitaet Hamburg, Hamburg, Federal Republic of Germany
• OSTI ID: 5119202
• Journal Information: Phys. Rev., C; (United States), Vol. 22:4
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COPPER 63 TARGET
HELIUM 3 REACTIONS
COPPER 65 TARGET
DEUTERON REACTIONS
COMPOUND-NUCLEUS REACTIONS
GALLIUM 66
ENERGY LEVELS
NIOBIUM 93 TARGET
YTTRIUM 89 TARGET
ZINC 64 TARGET
ZINC 66 TARGET
ALPHA SPECTRA
CHARGE DISTRIBUTION
EXCITATION FUNCTIONS
MEV RANGE 10-100
PRECOMPOUND-NUCLEUS EMISSION
PROTON SPECTRA
SPIN
STATISTICAL MODELS
ANGULAR MOMENTUM
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
ENERGY RANGE
FUNCTIONS
GALLIUM ISOTOPES
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISOTOPES
MATHEMATICAL MODELS
MEV RANGE
NUCLEAR REACTIONS
NUCLEI
ODD-ODD NUCLEI
PARTICLE PROPERTIES
RADIOISOTOPES
SPECTRA
TARGETS
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