Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.347100
Title: A study of the (₉Be, ₁₀B) reaction
Author: Winfield, John Stuart
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1983
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Abstract:
Angular distributions have been measured for the (9Be, 10B0, 1) reactions on 63Cu, 54Fe, 26,24Mg and 16O at 43 MeV and on 40Ca at 45 and 30 MeV. Several of these experiments were performed with the Oxford MDM-2 spectrometer and the design and testing of its 30 cm focal plane detector, which is of the "hybrid" type, is described. Despite the size of the counter, in particular the large cathode to Frisch-grid separation, the resolution of the ionization signals is comparable with that of smaller counters. The position resolution is < 0.6 mm. Optical potentials have been obtained from the measured elastic scattering of 9Be from 16O, 26Mg and 40Ca, and 10B from 25Mg and 39K. The exact finite-range DWBA calculations have generally well reproduced the shape of the experimental reaction cross-sections. However, inconsistencies of up to 50% between the extracted spectroscopic factors for 10B0 and 10B1 have been found. This anomaly was found insensitive to changes in either optical potential or bound state parameters. A new method of form factor calculation is described that uses a shell model potential in conjunction with a surface-peaked potential, the depth of which is adjusted to give the correct asymptotic form to the wavef unctions. Whilst this form factor showed some success, it did not account for the 10B0/10B1 anomaly. Collective model DWBA analyses of the inelastic excitation of the first 2+ state in 26Mg and 3- state in 40Ca have given values for deformation parameters in reasonable agreement with light-ion work. A CCBA analysis of the 26Mg 2+ state was carried out to estimate the effect of the coupling. Calculations performed for a two-step reaction process through inelastic excitation of a strongly coupled 5/2- state in the projectile showed that this indirect route is important, but it could not solve the 10B0/10B1 problem alone. The conclusion is that other routes (projectile or target excitation) must be included.
Supervisor: Jelley, Nicholas Alfred Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.347100  DOI: Not available
Keywords: Elastic scattering ; Heavy ions ; Inelastic scattering ; Angular distribution (Nuclear physics) Nuclear physics
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