Electromagnetic dissociation of sup 238 U in heavy-ion collisions at 120 MeV/A

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5190291

Justice, M L

The heavy-ion induced electromagnetic dissociation (EMD) of a 120 MeV/A {sup 238}U beam incident on five targets ({sup 9}Be, {sup 27}Al, {sup nat}Cu, {sup nat}Ag, and {sup nat}U) has been studied experimentally. Electromagnetic dissociation at this beam energy is essentially a two step process involving the excitation of a giant resonance followed by particle decay. At 120 MeV/A there is predicted to be a significant contribution ({approximately} 25%) of the giant quadrupole resonance to the EMD cross sections. The specific exit channel which was looked at was projectile fission. The two fission fragments were detected in coincidence by an array of solid-state {Delta}E-E detectors, allowing the charges of the fragments to be determined to within {plus minus} .5 units. The events were sorted on the basis of the sums of the fragments' charges, acceptance corrections were applied, and total cross sections for the most peripheral events (i.e. those leading to charge sums of approximately 92) were determined. Electromagnetic fission at the beam energy of this experiment always leads to a true charge sum of 92. The experimentally observed cross sections are due to nuclear interaction processes as well as electromagnetic processes. Under the conditions of this experiment, the cross sections for the beryllium target are almost entirely due to nuclear processes. The nuclear cross sections for the other four targets were determined by extrapolation from the beryllium data using a geometrical scaling model. After subtraction of the nuclear cross sections, the resulting electromagnetic cross sections are compared to theoretical calculations based on the equivalent photon approximation.

• Research Organization: California Univ., Berkeley, CA (United States)
• OSTI ID: 5190291
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDES
ALUMINIUM 27 TARGET
BASIC INTERACTIONS
BERYLLIUM 9 TARGET
CHARGED-PARTICLE REACTIONS
COMPARATIVE EVALUATIONS
COPPER
CROSS SECTIONS
DECAY
ELECTROMAGNETIC INTERACTIONS
ELEMENTS
ENERGY RANGE
EVALUATION
FISSION
FISSION FRAGMENTS
GIANT RESONANCE
HEAVY ION REACTIONS
INTERACTIONS
KINETICS
METALS
MEV RANGE
MEV RANGE 100-1000
NATURAL URANIUM
NUCLEAR FRAGMENTS
NUCLEAR REACTION KINETICS
NUCLEAR REACTIONS
PARTICLE DECAY
REACTION KINETICS
RESONANCE
SILVER
TARGETS
TOTAL CROSS SECTIONS
TRANSITION ELEMENTS
URANIUM
URANIUM 238 REACTIONS