When high-energy rays (such as x-rays and gamma rays) or other radioactive particles pass through some crystals, the crystals will emit fluorescence pulses due to the excitation of the particles. Crystals with this property are called scintillator crystals.Scintillator crystals are usually transparent to the fluorescence they emit, so if the scintillation crystals are coupled with the optical receiver such as CCD imaging board or photomultiplier, the crystal scintillation detection counter can be made.
According to the characteristics of luminescence, scintillating crystals can be divided into intrinsic scintillating crystals and non-intrinsic scintillating crystals. The former can glow without doping, such as BGO,CdWO4, CsI, BaF2, etc., while the latter needs doping and relies on introduced ion luminescence, such as Ce:YAG, Ce:GAGG, Ti:CsI, Eu:CaF2, etc.
Scintillation crystals are widely used in X-ray and gamma ray, neutron and other high-energy particle detection, in medical imaging, high-energy physics, nuclear physics, safety inspection, nondestructive testing of materials and geological prospecting and other fields.In medical field, for example, scintillation detector is the core of medical imaging equipment tumor diagnosis, represents the highest level of medical diagnosis (PET, CT), in the applications of gamma knife, also USES the scintillation detect gamma rays in the geophysical prospecting, can be channelled through Co60 gamma-ray deposit distribution through the analysis of the deposit after flashing signal, and so on and so forth in a large aerospace parts and other large industrial parts nondestructive flaw detection aspects such as scintillator plays a key role in the airport security check areas such as subway and freight container inspection of scintillator is also widely used as the detector.
According to different requirements of scintillator applications also vary, but generally scintillation crystals should have the following features: density is larger, the charged particles organization ability big, the ray has a high absorption coefficient, high luminous efficiency, luminous intensity has good linear relation with the energy of the incident ray, the fluorescence decay quickly, good optical homogeneity and on permeability good, the fluorescence requirements contained in the neutron probe is sensitive to neutron elements, etc.