Detector effects

In the experiment the physical time correlation between the stopped muon and its decay electron will be measured with high precision. Distortions of these time spectra arise if detector imperfections cause time dependent efficiency variations due to instrumental correlations

• between the muon and its decay electron (self correlation). The dominant source of self correlations is the detector response to the muon signal, which exceeds the minimum ionizing (MIPS) electron signal by two orders of magnitude. To avoid this effect, the muon and electron detector for the lifetime measurement are completely separate devices.
• between two overlapping muon-electron pairs (two event correlations). These latter effects, dubbed ``double kill'' were first discussed in our progress report [2] and then more generally studied in the context of the study of FAST systematics [21], which is subject to structurally very similar distortions. The quantitative model of these distortions depends on the detection method. Obviously, these distortions do not occur if only one muon is present during the measurement interval (pile-up free data set).