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BGO Bismuth Germanate
BGO (Bi4Ge3O12) is a high Z, high density scintillation material. Due to the high atomic number of bismuth (83) and the material's high density of 7.13 g/cm3, BGO is a very efficient gamma ray absorber. Given the high Z value of the material, the photo fraction for gamma ray absorption is high and as a result very good peak-to-total ratios are observed.
The radioactivity in BGO can make BGO unacceptable for some applications. We have developed a production process that significantly reduces the natural background, making our BGO well-suited for most applications.
Uses/Applications
- Positron Emission Tomography (PET)
- Physics - A Compton suppressor (also known as an anti-Compton shield or ACS)
Features/Benefits
- High Z
- High density
- Good photopeak to Compton ratio
- Scintillator of choice for neutron activation analysis and active Compton shields
BGO can be machined to various shapes and geometries. Since BGO is not hygroscopic it does not require a hermetic package. Arrays can be produced for imaging applications such as medical PET and security. For Physics experiments such as anti-Compton shields, crystals are typically packaged into larger annulus type detectors with multiple readout devices such as photomultiplier tubes.
- Available in large sizes and variable shapes
- Typical detector sizes range from 1" to 5" diameter and thicknesses up to 5"
- Other shapes; cube, hexagon
- Pixels (minimum 0.5mm square) or when used in an array down to 0.3mm
| Properties | Value |
|---|---|
| Density [g/cm3] | 7.13 |
| Melting point [K] | 1323 |
| Thermal expansion coefficient [C-1] | 7 x 10-6 |
| Cleavage plane | None |
| Hardness (Mho) | 5 |
| Hygroscopic | No |
| Wavelength of emission max. [nm] | 480 |
| Lower wavelength cutoff [nm] | 320 |
| Refractive index @ emission max | 2.15 |
| Primary decay time [ns] | 300 |
| Light yield [photons/keVγ] | 8-10 |
| Photoelectron yield [% of NaI(Tl)] (for γ-rays) | 15 - 20 |
| Temperature response | -1.2%/C |
| Neutron capture cross-section | 1.47b |
| Afterglow | @ 20ms 150ppm |