FOLGAT AG has long-year proofed and long-term joint operation partnership with the Institute for Single Crystals of the National Academy of Sciences of Ukraine
|Business management||Technology development team||Business Efficiency||Field of Applications|
Products and Services
|Single Crystals||Scintillation Detectors||Plastic Scintillators||Devices|
Common scintillators used for radiation detection include inorganic crystals, organic plastics and liquids. However, many materials scintillate at some level; scintillation of liquid xenon and neon plays a role in some ultra-low-background experiments. Most scintillators for common use are either inorganic crystals or plastics, the most common being thalium-doped sodium iodide crystals, which have a high radiation-to-light conversion efficiency. However, organic liquid scintillating fluids are well-suited for detecting very low energy particle radiation such as beta radiation from tritium by simply immersing the sample to be tested in the scintillation fluid, thereby negating detector absorption problems due to the very short mean free paths associated with low energy particles.
Types of Scintillators
- Inorganic crystals
- Plastic scintillators
- Organic crystals
- Liquid scintillators
Alkali - Halide Scintillators
The necessity to use NaI(Tl) crystals in sealed units is counterbalanced by the fact that they have the greatest light output among all the scintillators and a convenient emission range coinciding with a maximum efficiency of photomultipliers with bialkali photocatodes. Moreover, large-size NaI(Tl) crystals can be produced at a low cost.
CsI(Na) is a good alternative for NaI(Tl) in many standard applications because it has a high light output (85% of that of NaI(Tl)), the emission in a blue spectral region coinciding with the maximum sensitivity of the most popular PMT with bialkali photocatodes, and hygroscopicity substantially lower than that of NaI(Tl).
Since the maximum of emission spectrum is at 550 nm, photodiodes can be used to detect the emission. Because a scintillator-photodiode pair can be used, it is possible to reduce significantly the size of the detection system, to do without a high-voltage power supply, and to use the detection system in magnetic fields.
We offer a new scintillation material, CsI(CO3). The light output in gamma-excitation is 60% that of NaI(Tl). The decay time varies from 1.4 to 3.4 ms depending on the dopant concentration. These characteristics allow CsI(CO3) to be used in combination with other scintillators in phoswich detectors. CsI(CO3) has an afterglow of 0.05% after 5 microSec.
The decay time is ~10 ns. Undoped CsI can be effectively used for experiments in medium- and high-energy physics.
Selector Guide for Alkali Halide Scintillators
|Material||Important properties||Applications comments|
|NaI(Tl)||Very high light output, good energy resolution||General scintillation counting, monitoring, health physics, environmental high temperature use|
|CsI(Tl)||Non-hygroscopic, rugged, long wavelength emission||Particle - & high energy physics, general detection, photodiode readout, phoswiches|
|CsI(Na)||High light output, rugged||Geophysical|
|CsI(pure)||Fast, non-hygroscopic, radiation hard||High energy physics (calorimetry)|
|CsI(CO3)||Medium decay time, low afterglow||Gamma-detection, phoswich detectors|
|LiI(Eu)||High neutron cross-section, high light output||Thermal neutron detection and spectroscopy|
Physical Properties of Alkali Halide Scintillators
|Melting point [K]||924||894||894||894||894||719|
|Thermal expansion coefficient [K-1]||47.4x106||49x106||49x106||49x106||49x106||40x106|
|Wavelength of emission maximum [nm]||415||420||550||310||405||470|
|Refractive index at emission maximum||1.85||1.84||1.79||1.95||1.84||1.96|
|Light output [% of NaI(Tl)](for gamma rays)||100||85||45||5-6||60||30-35|
|Primary decay time [microSec]||0.23||0.63||1||0.01||2||1.4|
|Afterglow (after 6 microSec) [%]||0.3-5||0.5-5||0.1||-||0.06||-|
|Lower wavelength cutoff [nm]||300||300||320||260||300||425|
Plastic scintillators are a solid solution of luminophors (luminescent additives), in a transparent polymer (polystyrene (PST)). Many characteristics of plastic scintillation materials (light output, transparency to own emission, decay time, radiation resistance) can be varied by changing their composition. Polystyrene-based scintillators Scintillators with a polystyrene matrix are used to detect alfa-, beta, and gamma- radiation, and fast neutrons. Plastic scintillators are prepared by bulk polymerization in aluminium (size up to 3.5 m) or glass cast and by pressure molding technique.
- fast plastic scintillation material: decay time from 0.9 to 0.5 ns, light output 55-50% of anthracene;
- plastic scintillation material having the slow decay component: decay time from 300 to 400 ns, light output 45-40% of anthracene;
- radiation hard plastics (UPS-92RH with dia.16x10 мм has 50 % of the initial light output after irradiation at 18 МRad);
- plastic scintillation material of elevated radiation resistance;
- scintillation polystyrene with the light scattering additive;
- scintillation material for dosimetry;
- scintillation polystyrene containing soluted organic compounds of heavy elements (Pb -12%, Sn -10%).
|Absorption coefficient [cm-1]||0.01-0.003|
|Softening temperature [K]||355-360|
|Wavelength of emission maximum [nm]||430|
|Light output [% of anthracene]||5|
|Decay time [ns]||2-3|
Selector Guide for Plastic Scintillators
|Scintillators||Important properties||Applications comments|
|UPS-89, UPS-923A, UPS-90, UPS-96||Very high light output, good transparency, short decay time||General purpose, particle detection|
|UPS-92S||Slow decay time||Phoswiches|
|UPS-91F||Ultra fast decay time||High energy physics, calorimetry|
|UPS-92RH||Radiation hard||High energy physics, calorimetry|
|UPS-96M||Pressure molding technique, very cheap||High energy physics, calorimetry|
Physical Properties of Plastic Scintillators
|Scintillators||Light output % anthracene||Wavelength of max. emiss., nm||Rise time, ns||Decay time, ns||Light attenuation length, cm||Analoges|