In July 1999 the MUEX collaboration with people from Edinburgh and Tübingen has performed a measurement at PSI in order to search for decay branch in the muon decay leading to only two decay fragments.
These measurements are motivated by the observed timing anomaly in the KARMEN experiment. (will write more)
For a start three photos from the experimental setup.
After the last red beamline magnet one can see the first scintillator S1 used for coincidence, timing and vetoing subsequent particles. The muons stop in the middle germanium detector, and both stopping pulse and subsequent decay are measured. The detectors to the sides measure some of the annilation radiation emerging from the centre detector.
In addition to S1 there is a beam-defining second scintillator S2 right in front of the centre germanium detector to ensure that all muons are 'implanted' well in the germanium bulk and not near the side edge - at least all muons we measure. High energy decay positrons are supposed to cross at least a certain distance through the germanium and loose more energy than the energy range we are interested in.
This view from the top shows the relative placement of the detectors. The beamtime is over, and in dismounting the experiment the cables are already disconnected and the aluminium cover around the detectors removed. The detectors will be taken away shortly.