2026-09-22T15:39:17Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/25064 2023-07-10 col_2142_8859 col_2142_5131 com_2142_8858 com_2142_234 com_2142_5130

Koester, L.J. O'Fallon, Nancy Marie McCumber 2011-05-31T15:41:25Z 2011-05-31T15:41:25Z 10000-01-01 1966 Differential cross sections for the reaction He 3 (y,p)H2 were measured for photons of 45 to 150 MeV at five angular settings: (theta p , theta d) = (30°, 142°) I (60°, 106°), (90° I 75°), (120°, 47.5°), and (135°, 34.5°) in the laboratory. At ep of 60° and 90°, [equation] was obtained for photon energies down to 40 MeV. A gaseous He3 target at about 4°K and slightly less than one atmosphere pressure was bombarded with 250 MeV bremsstrahlung. The deuteron detection system, which was a telescope of three semiconductor detectors followed by a plastic scintillator, actually defined the solid angle. The proton telescope of four plastic scintillators was large enough to intercept all protons correlated with deuterons in the deuteron telescope. Photographs were made of the pulses from the detectors as displayed on an oscilloscope whenever there was a coincidence between a proton in the. proton telescope and a deuteron in the deuteron telescope. Pulse heights were used for particle identification and energy assignment.. The theta p = 90° cross sections ranged from 12.68 Z 0.45ub/sr to 1.07 ± 0.14ub/sr as photon energy increased. These 90° cross sections join quite smoothly with results of previous experiments. The total cross section as a function of photon energy, obtained by integrating the differential cross sections, decreased from 146 Z 5~b to 14 ~ 2~b as photon energy increased from 45 to 150 MeV. Integrated and bremsstrahlung-weighted cross sections obtained from the data of this experiment combined with data of lower energy experiments and of threebody photodisintegration experiments are 58.9 ~ 4.0 MeV rnb and 2.46 plus/minus .14 mb, respectively. Both values are in reasonable agreement with sum rule calculations, and the integrated cross section is in excellent agreement with a model-independent dispersion theoretic calculation which includes effects of all multipoles of electric interaction. It was not possible to fit the total cross section with the expression derived for electric dipole transitions with the Gunn and Irving wave function for the ground state of He3 for any reasonable value of the size parameter. With the size parameter that fits the low energy data, the calculated high energy cross sections are roughly a factor of two down from the measured cross sections. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-05-31T15:41:25Z No. of bitstreams: 1 1966_ofallon.pdf: 2945788 bytes, checksum: 794ef8eded01d78ad35ae2004809d610 (MD5) Made available in DSpace on 2011-05-31T15:41:25Z (GMT). No. of bitstreams: 1 1966_ofallon.pdf: 2945788 bytes, checksum: 794ef8eded01d78ad35ae2004809d610 (MD5) Previous issue date: 1966 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-05-31T15:41:25Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:12:26-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 6123876 http://hdl.handle.net/2142/25064 en 1966 Nancy Marie McCumber O'Fallon differential cross sections deuteron telescope proton telescope particle identification Differential cross sections for the reaction He[superscript 3] ([gamma],[rho]) H[superscript 2] from 45 to 150 MeV Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.