Measuring and modeling cosmic ray showers with an MBL system: An undergraduate project

Following a brief historical introduction, a novel method for inducing and measuring cosmic ray showers using a low-cost microcomputer-based laborator y system is described. This reproduction of Bruno Rossi's classic experimen t uses low counting-rate radiation monitors. The advantage of this is that a simple AND gate can be used to trigger coincidences, which makes the work ings of the experiment completely transparent to undergraduate students. Th e disadvantage is that data must be taken for many days to get reasonably a ccurate results. A simple theory is presented that models the resulting sho wer curve quite well. (C) 2001 American Association of Physics Teachers.