Experimental study of the reaction He3 ([v], [pi+])H3 up to 260 MeV

"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."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• O'Fallon, John Robert

Contributors dc:contributor

• Koester, L.J.

• pion scattering
• pion decay
• protons
• dueteron
• gaseous He

Statement dc:rights

• 1965 John Robert O'Fallon

Language dc:language

en

Identifier

6191828

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23977