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 NaI:Tl coupled to photo-multiplier tubes have exhibited excellent energy resolution of less than 7% 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 NaI:Tl. Single crystals of NaI: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 NaI:Tl crystals and fabricate scintillator detectors using photo-multiplierubes (PMT).

Sr. No.	Specification	Value
1	Crystal dimension (mm)	Diameter : 50 mm Length : 60 mm
2	Density [g/cm3]	3.67
3	Melting point [°C]	651
4	Energy resolution	Less than 7% at 662 keV
5	Hygroscopic	Yes
6	Wavelength of emission max. [nm]	420
7	Light yield [photons/keVγ]	38
8	Primary Decay time (ns)	250

1. Gamma-ray spectrometer
2. High energy radiation detectors
3. Nuclear Physics Experiments
4. Area monitor
5. Whole body counting
6. Oil well logging

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 NaI:Tl coupled to photo-multiplier tubes have exhibited excellent energy resolution of less than 7% at 662 keV, suitable to be used as radiation detectors in gamma-ray spectroscopy applications.

BARC has developed a novel crystal growth system based on the modified Bridgman technique to grow high quality, crack-free single crystals of NaI: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 NaI: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 NaI:Tl crystals and fabrication of scintillator detectors using photo-multiplier tubes (PMT).

Sr. No.	Specification	Value
1	Crystal dimension (mm)	Diameter : 50 mm Length : 60 mm
2	Density [g/cm3]	3.67
3	Melting point [°C]	651
4	Thermal expansion coefficient [°C-1]	Less than 7% at 662 keV
5	Cleavage plane	100
6	Hardness (Mohs)	2
7	Hygroscopic	Yes
8	Wavelength of emission max. [nm]	420
9	Refractive index @ emission max	1.85
10	Primary Decay time (ns)	250
12	Light yield [photons/keVγ]	38
13	Energy resolution	Less than 7% at 662 keV

1. Gamma-ray spectrometer
2. High energy radiation detectors
3. Nuclear Physics Experiments
4. Area monitor
5. Whole body counting
6. Oil well logging

space

1. 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

1. Growth Furnace
2. Dehydration unit
3. Weighing balance
4. Glove Box with humidity control (RH < 1%)
5. Cutting machines
6. PMT and associated electronics for testing
7. Glass blowing facility for sealing
8. Laminar flow bench

Consumables

1. Vacuum desiccators
2. Quartz crucible
3. Raw material
4. Process chemicals (alcohol, optical grease, oil)
5. Emery papers
6. Alumina powder
7. Liquid nitrogen

POWER

1. 220 V, 50 Hz, Single phase, 15 A

MANPOWER

1. One B.Sc. (Physics) and one M.Sc. (Physics) or equivalent degree.