The HERMES Experiment. I. Analyzing Powers in Pion Electroproduction. II. The Aerogel Radiator of the HERMES RICH

Citation

Carter, Paul Whitton (1999) The HERMES Experiment. I. Analyzing Powers in Pion Electroproduction. II. The Aerogel Radiator of the HERMES RICH. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ragp-vn42. https://resolver.caltech.edu/CaltechTHESIS:02232021-182253534

Abstract

Analyzing powers in pion electroproduction were measured in semi-inclusive deep inelastic scattering of longitudinally polarized positrons from a longitudinally polarized hydrogen target using the HERMES spectrometer in the DESY storage ring during the 1996 and 1997 data taking periods. The target spin and sin Φ dependent portion of the π⁺ production cross section was measured to be nonzero with high significance. The π^- result was consistent with zero within experimental errors. These results are compared and contrasted with existing experimental results and interpreted in the context of recent theoretical ideas.

Accurate particle identification over a large momentum range is crucial in measurements of semi- inclusive processes. To enhance its particle identification capabilities, the HERMES Experiment upgraded its spectrometer in 1998 with a ring imaging Čerenkov detector (RICH) using aerogel and C₄F₁₀ radiators. The use of aerogel in a RICH is a novel technique that requires a detailed understanding of its optical properties. A comprehensive series of measurements was carried out to characterize the generation and propagation of Čerenkov light in aerogel. The results were used to evaluate the expected performance of the aerogel radiator in the HERMES RICH.

Thesis Files