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.

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: https://theses.gla.ac.uk/id/eprint/3219