The TRIUMF TWIST experiment

The TWIST experiment at TRIUMF has been conducted by a Canadian-USA-Russia collaboration which has measured the parameters describing the decay at rest of polarized muons, with the goal of placing constraints on physics beyond the Standard Model. The original objective of an order of magnitude improvement on the precision with which the parameters rho, delta and Xsi,-which describe the positron momentum and emission angle spectra,-are determined is within reach and final analysis of the systematic uncertainties on the new measurements are almost complete. I will present an update on this important high precision experiment and place it in the context of several recent other muon decay measurements.