scintillation detector / gamma ray

These are Nal(Tl) Scintillation Detectors. A gamma ray when it interacts with such a detector, will produce a pulse of light which can be converted into an electric pulse using a PMT or photomultiplier tube. The detector is fitted with a photocathode, a focusing electrode, and ten dynodes and sometimes more than that, to multiply the number of electrons striking at each dynode. The PMT is fitted with a chain of resistors, to bias the anode and dynodes. The whole assembly can be ordered, including the scintillator and the PMT.