Equilibrium and non-equilibrium emission of complex fragments

Technical Report · Tue Aug 01 04:00:00 EDT 1989

DOI:https://doi.org/10.2172/5505929· OSTI ID:5505929

Bowman, D R

Complex fragment emission (Z{gt}2) has been studied in the reactions of 50, 80, and 100 MeV/u {sup 139}La + {sup 12}C, and 80 MeV/u {sup 139}La + {sup 27}Al, {sup nat}Cu, and {sup 197}Au. Charge, angle, and energy distributions were measured inclusively and in coincidence with other complex fragments, and were used to extract the source rapidities, velocity distributions, and cross sections. The experimental emission velocity distributions, charge loss distributions, and cross sections have been compared with calculations based on statistical compound nucleus decay. The binary signature of the coincidence events and the sharpness of the velocity distributions illustrate the primarily 2-body nature of the {sup 139}La + {sup 12}C reaction mechanism between 50 and 100 MeV/u. The emission velocities, angular distributions, and absolute cross sections of fragments of 20{le}Z{le}35 at 50 MeV/u, 19{le}Z{le}28 at 80 MeV/u, and 17{le}Z{le}21 at 100 MeV/u indicate that these fragments arise solely from the binary decay of compound nuclei formed in incomplete fusion reactions in which the {sup 139}La projectile picks up about one-half of the {sup 12}C target. In the 80 MeV/u {sup 139}La + {sup 27}Al, {sup nat}Cu, and {sup 197}Au reactions, the disappearance of the binary signature in the total charge and velocity distributions suggests and increase in the complex fragment and light charged particle multiplicity with increasing target mass. As in the 80 and 100 MeV/u {sup 139}La + {sup 12}C reactions, the lighter complex fragments exhibit anisotropic angular distributions and cross sections that are too large to be explained exclusively by statistical emission. 143 refs., 67 figs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5505929
• Report Number(s): LBL-27691; ON: DE90002685
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALUMINIUM 27 TARGET
ANGULAR DISTRIBUTION
CALCULATION METHODS
CARBON 12 TARGET
CHARGED-PARTICLE REACTIONS
COPPER
CROSS SECTIONS
DISTRIBUTION
ELEMENTS
ENERGY RANGE
FISSION FRAGMENTS
GOLD 197 TARGET
HEAVY ION REACTIONS
INCOMPLETE FUSION REACTIONS
LANTHANUM 139 REACTIONS
METALS
MEV RANGE
MEV RANGE 10-100
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
PARTICLE PROPERTIES
PARTICLE RAPIDITY
TARGETS
TRANSITION ELEMENTS