The quasi-deuteron model for the photo-emission of high energy neutron-proton pairs from oxygen 16 and calcium 40

Irvine, R. R (1967) The quasi-deuteron model for the photo-emission of high energy neutron-proton pairs from oxygen 16 and calcium 40. MSc(R) thesis, University of Glasgow.

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The benefit of using high energy gamma-rays to study nuclear structure and the information which can be gained from their use is first mentioned, with particular reference to the reaction in the title. The early history of the quasi-deuteron model is then sketched which leads up to a treatment of it by K.Gottfried. This is critically reviewed in detail and the main points of the theory, which are used as a basis of the latter part of the present work, are stressed. In deriving the cross-section for the photo-emission of high energy neutron-proton pairs from closed shell nuclei, Gottfried uses the cross-section for the photodisintegration of the deuteron to deal with the mechanism of the reaction and he then multiplies this by appropriate factors to account for the fact that the reaction is taking place inside a nucleus. These factors include: (A) a form factor p which is defined as the probability of finding a neutron-proton pair of combined momentum P at zero separation in the nucleus (B) a correction to allow for refraction of the photonucleons at the surface of the nucleus, and (C) a constant multiplying the cross-section to correct for absorption of the photo-pair on their way out of the nucleus. After a brief mention of related work to Gottfried by S.Fujii, new work that has been performed is described after the reasons motivating it have been given. This work consists of extending Gottfrieds work by doing a more complete calculation of the factor (B) for oxygen l6 to check the validity of Gottfrieds simpler calculation, evaluating (A) for calcium 4o for the first time and treating (C) in a different way for both oxygen l6 and and calcium 40 following a suggestion by N.MacDonald. The formulae derived have been numerically evaluated, with programmes written by the author on the KDF 9 computer of The University of Glasgow and the results are compared, where appropriate, with Gottfrieds results and the experimental results obtained from an experimental group at Glasgow University. The agreement and shortcomings revealed by these comparisons are discussed and conclusions drawn.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: N MacDonald
Keywords: High energy physics, Nuclear physics and radiation
Date of Award: 1967
Depositing User: Enlighten Team
Unique ID: glathesis:1967-72196
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 May 2019 15:11
Last Modified: 24 May 2019 15:11

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