Bismuth Germanate - BGO - Bi4Ge3O12 is a highly effective gamma-ray absorber as a result of its high density and high Z characteristics.
BGO Scintillator Crystals have:
- Mechanically robust characteristics and are non-hygroscopic
- Stable scintillating characteristics up to c.100 rad
- Virtually no afterglow emissions
- No cleavage planes, so can be easily machined into various shapes and geometries
Issues to be Noted:
- Have a light emission which is a good part is above 500nm, a region where photomultipliers are less sensitive
- Are intrinsically radioactive making it unacceptable for some applications
- Are susceptible to radiation damage, starting with doses between 1 and 10 Gray (102 - 103 rad). Reversible with time or annealing.
Common Applications:
- Positron Emission Tomography (PET)
- Compton suppression spectrometers
- Geological logging
- Specialist applications in high energy, nuclear, space and medical physics
Optical Properties
| Property |
Units |
Value |
| Wavelength (Max. Emission) |
nm |
480 |
| Wavelength Range |
nm |
375 - 650 |
| Decay Times |
ns |
300 |
| Light Yield |
photons/keV |
8-10 |
| Photoelectron Yield |
% of NaI(Tl) |
15-20 |
| Radiation Length |
cm |
1.118 |
| Radiation Length |
g.cm-2 |
7.97 |
| Moliere Radius |
cm |
2.259 |
| Optical Transmission |
µm |
0.15 - 12.5 |
| Transmittance |
% |
>90 (0.35 - 9µm) |
| Refractive Index |
|
2.15 (@480nm) |
| Reflection Loss/Surface |
% |
6.8 |
| Neutron Capture Cross-section |
barns |
1.47 |
Mechanical Properties
| Property |
Units |
Value |
| Chemical Formula |
|
(Bi2O3)2(GeO2)3 |
| Density |
g/cm³ |
7.13 |
| Atomic Number (Effective) |
|
74 |
| Melting Point |
ºC |
1044 |
| Thermal Expansion Coeff. |
C⁻¹ |
7.0 x 10-6 |
| Cleavage Plane |
|
None |
| Hardness |
Mho |
5 |
| Hygroscopic |
|
No |
| Solubility |
g/100g H₂O |
N/A |
Further Reading/Publications
Sizes
| Property |
Value |
| Diameters |
75mm max. |
| Lengths |
300mm max. |
