A scintillation detector or scintillation counter is obtained when a scintillator is coupled to an electronic light sensor such as:
- a photomultiplier tube (PMT),
- a charge-coupled device (CCD) camera,
All these devices may be used in scintillation counters and all convert the light to an electrical signal and contain electronics to process this signal. A photodiode is a semiconductor device that converts light into an electrical current. This is a semiconductor device which consists of a thin layer of silicon in which the light is absorbed after which free charge carriers (electrons and holes) are created. A conventional photodiode most often refers to a PIN diode. PIN means that the p and the n doped sides are separated by a depleted i-region. Electrons and holes are collected at the anode and cathode of the diode. This results in a photocurrent that is the output of the diode. The charge is however not amplified making the output signal amplitude small. This makes the photodiode sensitive to electronic noise. On the other hand, the quantum efficiency for the photodiode is high (60-80%) compared to the PMT (20-30%) which gives a higher energy resolution.