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Title:Experimental study of the reaction He3 ([v], [pi+])H3 up to 260 MeV
Author(s):O'Fallon, John Robert
Doctoral Committee Chair(s):Koester, L.J.
Department / Program:Physics
Subject(s):pion scattering
pion decay
gaseous He
Abstract:The differential cross section for the, reaction He3(y,n+)H3 was measured for photon energies of 180 to/260 MeV (momentum transfer 1.2 F-1 to 1.9 F-1). A target of gaseous He at 20.4 K and approximately one atmosphere preesure was irradiated by a 270 MeV bremsstrahlung x-ray beam. The reaction was obserVed by detecting , ' ' + 3 " . ,n .. H coinciq.ences. The counter telescopes consisted ()f seven plastic scintillators for the pions and four tl'ansmiss10ntype semiconduc1;or detectors for the tritons. Pulses froln the 'semiconductor detectors and the scintillators were displayed on a dual beam oscilloscope -.nd photographed. E and dE/dx relations were used for 'particle identification. Tritons with enere;ies between 9.7 and 24.5 MeV were observed at laboratory angles of 260,300, 350, and 400• '0 At 26 the cross sections in the center of mass system ranged from 2.55 !. 0.34 ~b/ster to 0.78 ±. 0.16~b/ster, decreasing with increasing photon ,energy. An impulse approximation calculation was performed to relate the cross section to the matter form factor of the 3-nucleon system under the assumption of 'identical wave functions for He3 and H3, Values for the matter form factor 'obtained using this relation and the cross sections of this experiment were found to lie below the values obtained from the results of electron scattering experiments. Several plausible arguments may be presented to explain this discrepancy. Under the condition of proximity of two nucleons, which depends on the internal momentum distribution, phase space considerations (Wilson model) lavor two nucleon ejection over free pion production. Pions may be scattered or absorbed before they escape the nucleus. Alterpatively, the pion production amplitude may have a many-body aspect; that is, 'it _y depend on the coordinates of more than one nucleon.
Issue Date:1965
Genre:Dissertation / Thesis
Rights Information:1965 John Robert O'Fallon
Date Available in IDEALS:2011-05-20
Identifier in Online Catalog:6191828

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