Muon decay: an old, yet alive experiment in the university physics curriculum

Abstract

The classic experiment on muon decay is proposed in the undergraduate or master physics curriculum, making use of a single scintillation detector and observing in coincidence the delayed signal due to the electron following muon decay. Two experimental setups, with different geometries and scintillation materials, were considered, making use of standard equipment available in most undergraduate labs. The results obtained in the two cases were compared and discussed. For a better understanding of the results, and to also evaluate the possible effect of material surrounding the detector, detailed GEANT simulations were carried out for both experimental setups. Such simulations are also intended as an additional student activity to virtually exploit in a short time the effect of modifying detector and material configuration, which cannot be achieved during a single student session. The results of this experiment and its interpretation also proved to be a useful way to discuss with students many topics of interest in modern physics, such as—among others—the time dilation, the dependence of muon lifetime in matter, the Fermi weak interaction coupling constant and the parity violation in weak interactions.