A coincident measurement of the three-body photodisintegration of helium-3
Kolb, Norman Reed
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https://hdl.handle.net/2142/21412
Description
Title
A coincident measurement of the three-body photodisintegration of helium-3
Author(s)
Kolb, Norman Reed
Issue Date
1990
Doctoral Committee Chair(s)
Smith, J.H.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Nuclear
Language
eng
Abstract
This experiment measured coincident neutron-proton pairs from the photodisintegration of $\sp3$He. The bremsstrahlung photon beam was produced by a 100 MeV electron beam, supplied by the University of Illinois Nuclear Physics Laboratory 100% duty factor electron microtron. The energy and angle of the np pairs were used to reconstruct the energy of the photon, making this a kinematically complete experiment. The $\sp3$He($\gamma$,np)p data were normalized to measured $\sp2$H($\gamma$,np) yields and published deuterium photodisintegration cross sections.
The target was a cryogenic system which maintained the $\sp3$He gas at liquid $\sp4$He temperature. Protons were detected with a dE-E scintillation telescope and neutrons with a position sensitive scintillation array. The proton energy was determined from the energy deposited in a NaI crystal and the neutron energy from the time of flight over a 4 m path. The neutron and proton were detected on opposite sides of the photon beam at opening angles from 122-202 degrees in the lab frame.
Quasi-deuteron breakup events were detected for photon energies of 45-95 MeV. Strong final state interactions prohibited an accurate determination of the quasi-deuteron contribution to the cross section. The single differential cross section $(d\sigma/d\Omega\sb{p})$ for $\sp3$He at $\theta\sb{p}$ = 81$\sp\circ$ was determined by integrating the neutron angular distribution. This cross section, relative to deuterium, ranged from 2.39 $\pm$.16 at 55 MeV to 1.67 $\pm$.27 at 95 MeV.
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