TWIST Summer Student: Clay Lindsay

The TRIUMF Weak Interaction Symmetry Test, or TWIST, seeks to study polarized muon-to-positron decays to high precision in order to test symmetries in the weak interaction. TWIST's 2004 data run included the addition of a sub-detector to the main apparatus in order to precisely characterize the muon beam: a time expansion chamber (TEC). On first analysis of this data run, the time expansion chamber's response produced unexpected results. The response expectations assumed a constant electric field within the TEC's modules. A detailed study of the electric field within the TEC is necessary to properly understand and preict the TEC's response for future data runs. This report describes the TEC geometry, a simulation of that geometry, and a numerical solution for the electric field inside the modules. Geometry modifications are explored and recommendations are made with regard to these modifications.