OK, i'm currently in the process of designing an experiment to measure the rest lifetime of the muon, using a vertical stack of four flat scintillation detectors seperated by lead plates, and coincidence electronics, Time-Amplitude converter, etc. to acquire data from the cosmic ray muons reaching sea level, and their corresponding decay electrons. Now, the only bit i'm having trouble figuring out is determining the efficency of the scintillators experimentally. We can say that eff(A) can be calculated as 1 - ((N((a')bc) / N(abc)) and expressions like that, where the efficency of A is a quantification of the number of particles detected in A (A being the top of the 4 scintillators, followed by B, C and D) relative to the actual number passing through it, where N((a`)(bc), for example, is the number of counts from B AND C and NOT A, and so forth. Now, the bit i'm not understanding is the acceptance correction terms which need to be included in these efficency calculations, where by acceptance i mean the quantity which quantifies the muons passing out the side of the detector stack. I know i'm not explaining this very well, i'm sorry, but i'm sure some of you recognise what i'm trying to set up. Could someone explain to me how the acceptances can be included in the efficency calculations, or provide any good references for peforming the calculations for this kind of experiment? Cheers.