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Title: Coherent neutral pion photoproduction on ¹⁶O and ²⁰⁸Pb
Author: Sanderson, Ruth
ISNI:       0000 0001 3551 0797
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 2002
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Neutral pion photoproduction in nuclei has particular potential as a source of information on the matter distribution in nuclei but it also has important contributions to make in extending our knowledge of the pion-nucleus interaction and the medium modifications of the pion production process. This thesis presents the experimental study of coherent neutral pion photoproduction on 16O and 208Pb performed using the tagged photon beam facility at MAMI-B, University of Mainz, and the TAPS photon spectrometer, a highly segmented detector array built to detect light mesons. Total and differential cross sections were measured in the incident photon energy range 135-380 MeV, covering a wider angular range and with smaller statistical errors than previous measurements. The diffraction-like structure of the differential cross section due to the nuclear form factor was demonstrated. Comparisons were made with plane and distorted wave impulse approximation models and show the importance of including a description of the final state interaction in the theoretical predictions but suggest that the magnitude of the pion-nucleus interaction is underestimated in the DWIA. Comparison with the Delta resonance energy model suggests that the nuclear medium does affect the Delta properties but that modifications are needed to the parameterisation used. An assessment of the A-dependence of the total coherent (gamma,pi0) cross section was made using the measurements on 12C and 40Ca performed at the same time as the present experiment. This comparison reinforces the conclusion that there is medium modification of the Delta and also suggests that this modification may have an A-dependence.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Elementary particles & high energy physics