UBC Theses and Dissertations
A proton polarimeter for pion physics at TRIUMF Pavan, Marcello Maurizio
A proton polarimeter employing multi-wire delay-line drift chambers (MWDDCs) has been built for ongoing pion absorption studies in the meson area at TRIUMF. A brief introduction of the theoretical basis of polarimeter and MWDCC operation is offered. An in-depth study of our own system is presented including an account of the data acquisition readout electronics and the procedures used for wire chamber position calibration. Detailed performance specifications of all aspects of our chamber are given, notably for the method used to solve the drift chamber left/right ambiguity. The chambers are found to operate reliably and efficiently with very good spatial resolution, σ = ~200µm. The systematic artificial asymmetry in the polarimeter is also studied. Finally, scattering-efficiency and figure-of-merit ([formula omitted]) results are presented for 230 MeV protons scattering off a 7cm carbon analyzer in the three cases of ø + π and 2π azimuthal scattering acceptance symmetry, and full polarimeter acceptance. In particular, it is found that when employing the Besset weighted-sums polarization extraction technique, imposition of ø + π azimuthal scattering symmetry results in only a small increase in measured statistical error compared to results obtainable from a full Fourier spectrum analysis with no applied acceptance symmetry. Suggestions for improvements to established practices are offered throughout.
Item Citations and Data