Technology to grow single crystals of CsI:Tl using the modified Bridgman technique is developed in BARC. Single crystals of size 50 mm diameter and 60 mm length can be grown in this system. Further, processing of grown crystals and coupling of the scintillator crystal to suitable photo-detectors to fabricate nuclear radiation detectors has been offered in the technology.
Parties with sound financial background, relevant experience in nuclear radiation detectors, having clean room atmosphere and with conditioned ambient would be preferred.
Single crystals of alkali halide inorganic scintillators are useful as nuclear radiation detectors in gamma-ray spectroscopy and radiography applications. These crystals are grown in silica crucibles using the vertical Bridgman technique. Crystals of CsI:Tl coupled to suitable photo-detectors have exhibited excellent energy resolution of less than 8% at 662 keV, suitable to be used as radiation detectors in gamma-ray spectroscopy for the identification of radio-active nuclides.
BARC has developed a novel crystal growth system based on the modified Bridgman technique to grow high quality, crack-free single crystals of CsI:Tl. Single crystals of CsI:Tl up to 50 mm in diameter and 60 mm in length could be grown with almost 100% yield. Expertise has been developed to process the grown CsI:Tl crystals and fabricate scintillator detectors using photo-diodes as well as PMTs.
| Sr. No. | Specification | Value |
|---|---|---|
| 1 | Crystal dimension (mm) | Diameter : 50 mm, Length : 60 mm |
| 2 | Density [g/cm3] | 4.51 |
| 3 | Melting point [°C] | 621 |
| 4 | Energy resolution | Less than 8% at 662 keV |
| 5 | Hygroscopic | slightly |
| 6 | Wavelength of emission max. [nm] | 550 |
| 7 | Lower wavelength cutoff [nm] | 320 |
| 8 | Light yield [photons/keVγ] | 54 |
| 9 | Photoelectron yield with PMT [% of NaI(Tl)] (for γ-rays) | 45 |
| 10 | Primary Decay time (ns) | 1000 |
INTRODUCTION
Single crystals of alkali halide inorganic scintillators are useful as nuclear radiation detectors in gamma-ray spectroscopy and radiography applications. These crystals are grown in silica crucibles using the vertical Bridgman technique. Crystals of CsI:Tl coupled to suitable photo-detectors have exhibited excellent energy resolution of less than 8% at 662 keV, suitable to be used as radiation detectors in gamma-ray spectroscopy applications. The CsI:Tl being less hygroscopic in nature is easier to handle compared to NaI:Tl crystal. Secondly, the emission from CsI:Tl scintillator at 550 nm makes it suitable to be coupled to photo-diodes to fabricate compact devices operating at lower voltages compared to PMT.
BARC has developed a novel crystal growth system based on the modified Bridgman technique to grow high quality, crack-free single crystals of CsI:Tl. Easy extraction of the grown crystal is achieved using a uniquely designed silica crucible and an ingenious furnace design that has precise temperature control mechanism and highly accurate motor for lowering the crucible. Single crystals of CsI:Tl up to 50 mm in diameter and 60 mm in length could be grown with almost 100% yield. The technology also covers processing of the grown CsI:Tl crystals and fabrication of scintillator detectors using photo-diodes as well as PMTs.
SPECIFICATIONS
| Sr. No. | Specification | Value |
|---|---|---|
| 1 | Crystal dimension (mm) | Diameter : 50 mm, Length : 60 mm |
| 2 | Density [g/cm3] | 4.51 |
| 3 | Melting point [°C] | 621 |
| 4 | Thermal expansion coefficient [°C-1] | 54 x 10-6 |
| 5 | Cleavage plane | none |
| 6 | Hardness (Mohs) | 2 |
| 7 | Hygroscopic | slightly |
| 8 | Wavelength of emission max. [nm] | 550 |
| 9 | Lower wavelength cutoff [nm] | 320 |
| 10 | Refractive index @ emission max | 1.79 |
| 11 | Primary Decay time (ns) | 1000 |
| 12 | Light yield [photons/keVγ] | 54 |
| 13 | Energy resolution | Less than 8% at 662 keV |
RAW MATERIALS
About 600 sq feet (25x25 sq. ft) roofed area with proper arrangement of cleanness (preferably Class 10,000), dust proof with controlled temperature (25±1°C) and humidity (<55%) with continuous electricity.
EQUIPMENTS
Consumables
POWER
MANPOWER
