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

Abstract

This thesis describes a measurement of the heavy-ion induced electromagnetic dissociation 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. 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 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 changes 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 were determined. Electromagnetic fission at the beam energy of this experiment always leads to a true charge sum of 92. Due to the imperfect resolution of the detectors, charge sums of 91 and 93 were included in order to account for all of the electromagnetic fission events. The experimentally observed cross sections are due tomore » 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. Systematic uncertainties are discussed and suggestions for improving the experiment are given.« less

Authors:
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
5592089
Report Number(s):
LBL-31704
ON: DE92008313
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALUMINIUM 27 TARGET; URANIUM 238 REACTIONS; BERYLLIUM 9 TARGET; COPPER; SILVER; URANIUM; ELECTROMAGNETIC INTERACTIONS; CALIBRATION; CROSS SECTIONS; DISSOCIATION; MONTE CARLO METHOD; PLASTIC SCINTILLATION DETECTORS; ACTINIDES; BASIC INTERACTIONS; CHARGED-PARTICLE REACTIONS; ELEMENTS; HEAVY ION REACTIONS; INTERACTIONS; MEASURING INSTRUMENTS; METALS; NUCLEAR REACTIONS; RADIATION DETECTORS; SCINTILLATION COUNTERS; SOLID SCINTILLATION DETECTORS; TARGETS; TRANSITION ELEMENTS; 663450* - Heavy-Ion-Induced Reactions & Scattering- (1992-); 663520 - Nuclear Mass Ranges- A=6-19- (1992-); 663530 - Nuclear Mass Ranges- A=20-38- (1992-); 663590 - Nuclear Mass Ranges- A=220 & Above- (1992-); 663560 - Nuclear Mass Ranges- A=90-149- (1992-); 663550 - Nuclear Mass Ranges- A=59-89- (1992-)

Citation Formats

Justice, M L. Electromagnetic dissociation of sup 238 U in heavy-ion collisions at 120 MeV/A. United States: N. p., 1991. Web. doi:10.2172/5592089.
Justice, M L. Electromagnetic dissociation of sup 238 U in heavy-ion collisions at 120 MeV/A. United States. https://doi.org/10.2172/5592089
Justice, M L. 1991. "Electromagnetic dissociation of sup 238 U in heavy-ion collisions at 120 MeV/A". United States. https://doi.org/10.2172/5592089. https://www.osti.gov/servlets/purl/5592089.
@article{osti_5592089,
title = {Electromagnetic dissociation of sup 238 U in heavy-ion collisions at 120 MeV/A},
author = {Justice, M L},
abstractNote = {This thesis describes a measurement of the heavy-ion induced electromagnetic dissociation 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. 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 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 changes 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 were determined. Electromagnetic fission at the beam energy of this experiment always leads to a true charge sum of 92. Due to the imperfect resolution of the detectors, charge sums of 91 and 93 were included in order to account for all of the electromagnetic fission events. 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. Systematic uncertainties are discussed and suggestions for improving the experiment are given.},
doi = {10.2172/5592089},
url = {https://www.osti.gov/biblio/5592089}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Apr 01 00:00:00 EST 1991},
month = {Mon Apr 01 00:00:00 EST 1991}
}