BaF2 Scintillator Crystal
BaF2 - Barium Fluoride - is a salt compound of barium and fluorine. In crystal form it is optically transparent over a wide range from the UV through to the IR and widely used to fabricate optical components. It is also has a well established scintillator material.
BaF2 Scintillator Crystals Feature:
- One of the fastest scintillators with a sub-nanosecond decay time
- Optical emissions in the form of a ‘fast’ and ‘slow’ pulses
- Good ‘rad hard’ properties (up to 105 rad)
- Do not glow in the UV
- An optical output independent of temperature
Issues to be Aware Of:
- Slightly hygroscopic with long term exposure to moisture affecting the quality of the surface
- Very sensitive to thermal shock which can cause fracturing
Common Applications:
- Time-of-Flight measurements
- Positron lifetime studies
- Positron Emission Tomography (PET)
- Discrimination between gamma rays and neutrons
- Specialist applications in nuclear and high energy physics
Optical Properties
| Property | Units | Value |
|---|---|---|
| Wavelength (Max. Emission) | nm | 310 (Slow) 195/220 (Fast) |
| Wavelength Range | nm | 170 - 460 |
| Decay Times | ns | 630 (Slow) 0.87/0.88 (Fast) |
| Light Yield | photons/keV | 10 (Slow) 1.9 (Fast) |
| Photoelectron Yield | % of NaI(Tl) | 16 (Slow) 3 (Fast) |
| Radiation Length | cm | 2.026 |
| Radiation Length | g.cm-2 | 9.91 |
| Moliere Radius | cm | 3.117 |
| Optical Transmission | µm | 0.15 - 12.5 |
| Transmittance | % | >90 (0.35 - 9µm) |
| Refractive Index | 1.49 (@ 310nm) | |
| Reflection Loss/Surface | % | 6.8 |
Mechanical Properties
| Property | Units | Value |
|---|---|---|
| Chemical Formula | BaF2 | |
| Density | g/cm³ | 4.893 |
| Atomic Number (Effective) | 52.2 | |
| Crystal Structure | Cubic | |
| Lattice Constant | nm | 0.6196 |
| Melting Point | ºC | 1386 |
| Thermal Expansion Coeff. | C⁻¹ | 18.4 x 10-6 |
| Hardness | Mho | 3 |
| Hygroscopic | Slightly | |
| Solubility | g/100g H₂O | 0.17 (23ºC) |
