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Which radiation detectors can respond to a single particle or photon?
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radiation measurement
Figure 1: (A) A simple equivalent circuit for the development of a voltage pulse at the output of a detector. R represents the resistance and C the capacitance of the circuit; V(t) is the time (t)-dependent voltage produced. (B) A representative current pulse due to the interaction of a single quantum in the detector. The total charge Q is obtained by integrating the area of the current, i(t), over the collection time, tc. (C) The resulting voltage pulse that is developed across the circuit of (A) for the case of a long circuit time constant. The amplitude (Vmax) of the pulse is equal to the charge Q divided by the capacitance C.
Several types of radiation detectors are capable of responding to a single particle or photon, providing a real-time signal for each individual quantum of radiation. These devices generally operate in "pulse mode," where the interaction of a single particle or photon generates a discrete electrical pulse.12
Common detectors with single-quantum sensitivity include:
- Gas-filled detectors: Both proportional counters and Geiger-Müller tubes are designed to detect individual particles by producing an electrical pulse following ionization.31
- Semiconductor detectors: Devices such as silicon diode detectors and coaxial germanium detectors detect the electron-hole pairs created by a single incident particle or photon.145
- Scintillation detectors: When paired with a photomultiplier tube, these detectors can identify the burst of light produced by a single photon.61
- Other specialized detectors: The bubble chamber and Cerenkov detectors are also capable of single-particle detection. Additionally, certain passive detectors, such as nuclear emulsions and track-etch films, can record the tracks of individual particles.1