(This explanation is posted outside the Nuclear Chemistry laboratory CSH 345)
The PUC Cosmic Ray Detector
Even as you stand here we are detecting cosmic rays in the Nuclear Chemistry laboratory. Specifically we have constructed an omnidirectional cosmic ray detector which detects muons (mu mesons). At our elevation in Angwin, most of the cosmic rays are muons. The computer (a PC) in the laboratory takes the data, stores it in a file and displays the data on its monitor. Not only are we detecting muons but also we are measuring the muon lifetime. You can see displayed on the monitor the number of muons as a function of time (time after the muon stops in the detector). This is a time spectrum. The time span across the entire horizontal axis is approximately 20 microseconds (20 x 10-6 sec).
The muon (m ) decays into an election (e) and two neutrinos (v):
Our students in the Nuclear Chemistry laboratory can measure the m lifetime and typically get values within a few percent of the accepted value.
