Cerenkov ring imaging and spectroscopy of charged Kstar interactions at 11 GeV/c.

摘要

A thesis in two independent halves.; Part I. A scientific proof-of principle prototype was constructed and tested in order to evaluate the performance capabilities of a ring imaging Cerenkov detector. The detector measures the velocity of relativistic particles, and is the first Cerenkov counter to take advantage of the most fundamental properties inherent to Cerenkov radiation. Single photons from the Cerenkov cone of a radiating particle in a gas or liquid Cerenkov medium are focussed into a ring. Those Cerenkov photons with far ultraviolet wavelengths of the electromagnetic spectrum are converted to electrons, with high efficiency, in the uniform electrostatic field of an electron drift tube. The electrons are drift in the field to a novel proportional wire chamber which is sensitive to single electrons. Analysis of the reconstructed Cerenkov rings from an 11 GeV/c test beam show that an excellent velocity measurement can be obtained, allowing clean {dollar}pi{dollar}/K particle identification at a level of {dollar}sim{dollar}15 standard deviations to be achieved.; The physics and technology of this new Cerenkov detector are discussed, including materials studies, construction techniques, and resolution measurements. Sources of resolution error are individually identified and measured where possible. The results of all studies indicate that the measurement resolution is understood. This work has led to the adoption of a large scale ring imaging detector as part of a new high energy physics spectrometer, the SLD, at the Stanford Linear Accelerator Center.; Part II. Results from an amplitude analysis of strange meson final states in {dollar}Ksp- p to overline{lcub}Ksb0{rcub}pisp- p{dollar} interactions are presented. The data derive from a 4 event/nb exposure of the LASS (Large Aperture Superconducting Solenoid) spectrometer to an 11 GeV/c {dollar}Ksp-{dollar} beam. The data sample consists of {dollar}sim{dollar}100,000 events distributed over the Dalitz plot of the channel.; The process is observed to be dominated by the production and decay of natural spin-parity ({dollar}Jsp{lcub}P{rcub} = 1sp-,2sp+,3sp-,{dollar} ...) strange meson states. The data can be understood in terms of a simple model in which the resonant {dollar}overline{lcub}Ksp{lcub}* -{rcub}{rcub}{dollar} are produced predominantly via natural parity exchange in the t channel. The leading {dollar}Ksp*{dollar}(890), {dollar}Ksbsp{lcub}2{rcub}{lcub}*{rcub}{dollar}(1430), and {dollar}Ksp*{dollar}(1780) resonances are clearly observed and measured, and the underlying spectroscopy is also extracted. Indications of higher mass resonance production are also shown.; The observed properties of these states are used to confront current models of quark spectroscopy in strange meson systems.