Coherent Neutral Pion Photoproduction on 16O and 208Pb

Sanderson, Ruth (2002) Coherent Neutral Pion Photoproduction on 16O and 208Pb. PhD thesis, University of Glasgow.

Abstract

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.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: R Owens
• Keywords: High energy physics, Nuclear physics and radiation
• Date of Award: 2002
• Depositing User: Enlighten Team
• Unique ID: glathesis:2002-76217
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 16:27
• Last Modified: 19 Nov 2019 16:27
• URI: https://theses.gla.ac.uk/id/eprint/76217