Abstract
A drift chamber module with 5 anode wires covering an active region of 9 cm x 76 cm has been built to locate the vertical position of a-particle trajectories to within 295 mm full-width-half-maximum (FWEM) in isobutane at a pressure of 0.25 atm. Modules will be used with the Multipole-Dipole-Multipole Spectrometer in a-particle scattering experiments to measure vertical angles of trajectories needed for ray tracing. The physics of drift chambers is described and used to discuss the operational characteristics of chambers built by other authors and the design of the drift chamber module presented here. Sources of localization uncertainty in the drift chamber module are discussed and the performance of the drift chamber module is predicted based on the physics. Drift chamber modules were tested with 240 MeV a particles using isobutane and an E/P ratio of 2000 V/(cm-atm) at several pressures. The operational characteristics of isobutane were sufficient to obtain high-resolution measurements using the drift chamber module even though up to 6 % more multiwire events occurred in the module than was expected. Trajectories were located to within 225 mm ︢5 / mm (FWHM) at a pressure of 0.25 atm. The resolution measured experimentally was larger than what was predicted. This suggests that the localization uncertainty due to variations in flight times of ionization electrons was larger than expected and/or the localization uncertainty due to the timing resolution of the electronics was larger than expected.
Oliver, Jon Patrick (1996). A high-resolution drift chamber for Alpha-particle position measurements. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1996 -THESIS -O454.