Bismuth Germanate scintillator, BGO scintillation crystal

Bismuth Germanate (Bi₄Ge₃0₁₂ or BGO) is one of the most widely used scintillation materials of the oxide type. It has high atomic number and density values. Detectors based on BGO have volume 10 - 4 times and mass 5 - 7 times less than those with Alkali Halide scintillators. BGO is mechanically strong enough, rugged, non-hygroscopic, and has no cleavage .BGO has an extreme high density of 7.13 g /cm3 and has a high Z value which makes these crystals very suitable for the detection of natural radioactivity (U, Th, K), for high energy physics applications (high photofraction) or in compact Compton suppression spectrometers.
BGO detectors are characterized by high energy resolution in the energy range 5 - 20 MeV, a relatively short decay time; its parameters remain stable up to the doses of 5 x 10⁴ Gy; large-size single crystals are possible to obtain. Due to these features, BGO crystals are used in high-energy physics (scintillators for electromagnetic calorimeters and detecting assemblies of accelerators), spectrometry and radiometry of gamma-radiation, positron tomography

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