The aim of the TWIST experiment, carried out at the muon beam at TRIUMF (Vancouver, Canada), was to accurately measure the Michel parameters ρ, δ and Pµξ in the decays of positive muons with an accuracy of 10^–4, that would improve the then existing results approximately by an order of magnitude. To achieve this goal, it was necessary to create a spectrometer with high geometric accuracy and measure the energy of decay positrons with an accuracy of 10^–3.

The report discusses methods for creating wire detectors and the parameters of the TWIST spectrometer. Methods for analyzing data and estimating systematic uncertainties in getting Michel parameters are discussed. The measured Michel parameters were approximately an order of magnitude more accurate than pre-TWIST results and were included in the data of Particle Data Group.