In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a particle accelerator. Detectors can measure the particle energy and other attributes such as momentum, spin, charge, particle type, in addition to merely registering the presence of the particle.

The operating principle of a nuclear radiation detector can be summarized as follows:

The detector identifies high-energy particles or photons—such as alpha, beta, gamma radiation, or neutrons—through their interactions with the atoms of the detector material. These interactions generate a primary signal, which may involve ionization of gas, the creation of electron-hole pairs in semiconductors, or the emission of light in scintillating materials. The primary signal is then amplified and processed by electronic systems. Finally, the resulting electrical pulse is analyzed to determine characteristics of the radiation, such as its energy, count rate, or spectral distribution.

Many of the detectors invented and used so far are ionization detectors (of which gaseous ionization detectors and semiconductor detectors are most typical) and scintillation detectors; but other, completely different principles have also been applied, like Čerenkov light and transition radiation.

Historical examples

The following types of particle detector are widely used for radiation protection, and are commercially produced in large quantities for general use within the nuclear, medical, and environmental fields.

Electroscope (when used as a portable dosimeter)

Commonly used detectors for particle and nuclear physics