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Measurement of polarisation observables using linearly polarised photons with the crystal ball at MAMI

Howdle, David A. (2012) Measurement of polarisation observables using linearly polarised photons with the crystal ball at MAMI. PhD thesis, University of Glasgow.

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Abstract

In order to further study and expand the kinematic coverage of polarisation observables in pseudoscalar meson photoproduction, a measurement of polarisation observables has been performed at the MAMI facility in Mainz, Germany. The measurement used a beam of linearly polarised photons using the coherent bremsstrahlung method and the Glasgow Tagged Photon Spectrometer. The photon beam was incident on an $lH_{2}$ target in order to produce the meson photoproduction reaction $\gamma p \to \pi^{0} p$. This target was housed in the centre of the Crystal Ball detector which was used to detect the reaction products. A carbon polarimeter was used to measure the polarisation of the recoiling proton through secondary scattering. The polarisation observables for pseudoscalar meson photoproduction which were measured included: $\Sigma$, the modulation induced in the reaction products by the linearly polarised photon beam; $O_{x}$, the transfer of linear polarisation from the beam to the recoiling proton; and $T$, the polarisation inherent in the target proton. These measurements were performed over a wide kinematic range in both photon energy and polar angle in the centre of mass system, and were compared to three partial wave analyses, SAID, MAID and Bonn-Gatchina. The results contribute to the ongoing search for a complete understanding of the nucleon's excitation spectrum, and significantly enhance the world dataset for these polarisation observables.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: nuclear, polarisation observables, pseudoscalar meson, meson photoproduction
Subjects: Q Science > QC Physics
Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
Supervisor's Name: MacGregor, Dr. Douglas
Date of Award: 2012
Depositing User: Dr David Howdle
Unique ID: glathesis:2012-3219
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 09 Mar 2012
Last Modified: 10 Dec 2012 14:05
URI: http://theses.gla.ac.uk/id/eprint/3219

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