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A theoretical consideration of the direct capture process O¹⁶ (p,[gamma]) F⁷ at low energies

The cross sections for the 0¹⁶ (p,ɤ) F¹⁷ transitions to the ground d-state and to an excited s-state of F¹⁷ have been
measured in this laboratory and elsewhere, at different energies
in the range from about 100 kev to 2.5 Mev incident proton energy. In this thesis an attempt is made to calculate these cross sections
at several energies in the above range on the hypothesis of direct proton capture. Similar calculations have been made at the California Institute of Technology but have not been published.
The standard formula for the cross section for an electric
dipole transition from an incident p state to a final d-or s-state has been used. The matrix element appearing in this formula
was split up into an angular part which can be evaluated exactly, and a radial integral which has to be calculated approximately.
In the case of transitions to the excited s-state numerical
calculations using tabulated wave-functions were made at center of mass proton energies of 150, 378 and 940 kev. The cross section at 150 kev was also calculated by the saddle point method using WKB approximations to the wave-functions, but this method was found to break down at energies above 200 kev due to difficulties
with the WKB functions. Reasonably good agreement between the two methods was obtained at 150 kev.
For transitions to the ground d-state the numerical method could not be used since tabulations of the required d-state
wave-function are unavailable. Calculations were made only by the saddle point method at center of mass proton energies of 150, 378 and 500 kev. This method can not be used above 500 kev.
The calculated ratio of [formula omitted] ≈ 9 at energies of 150
and 378 kev, and the absolute values of the cross sections agree reasonably well with the experimentally observed values. Some discrepancies are noted between these calculations and those carried out at the California Institute of Technology which are very briefly referred to in a preprint of an experimental paper, but a detailed comparison was not possible, as the details of those calculations are unavailable. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Identiferoai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/40408
Date January 1959
CreatorsNash, George Francis
PublisherUniversity of British Columbia
Source SetsUniversity of British Columbia
LanguageEnglish
Detected LanguageEnglish
TypeText, Thesis/Dissertation
RightsFor non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

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