Hello, I have a question about coincidence event. Let us take the decay of deuteron to proton and alpha particle, (d, pα). p and α goes in opposite direction. So, if we put two detectors in opposite directions, one of them will detect p and another will detect α simultaneously (within a small time window). If the solid angle covered by both detectors are same (say Ω) and if one of the detector detect p then it is sure that another one will detect α. If N0 be the total decay rate then number of coincidence event detected will be N0Ω. However, if the solid angle covered by the detectors are different, say Ω1 and Ω2 such that Ω1 > Ω2 then the number of coincidence event will be equal to the number of events detected by the second detector because other extra event detected by the larger detector won't be detected by the smaller detector. Are these reasoning right? Because in a book, I saw the number of coincidence event is N0Ω1Ω2. Thanks.