Basic Properties
Crystal	Bi12SiO20 (BSO)	Bi12GeO20 (BGO)
Symmetry	Cubic, 23	Cubic, 23
Melting Point	900 °C	930 °C
Density	9.2 g/cm³	9.2 g/cm³
Mohs Hardness	4.5	4.5
Transparencey Range	450 – 7500 nm	470 – 7500 nm
Transmittance at 633 nm	69%	67%
Refractive Index at 633 nm	2.54	2.55
Dielectric Constant	56	40
Electro-optic Coefficient	r41 = 5 x 10-12 m/V	r41 = 3.4 x 10-12 m/V
Resistivity	5 x 1011W-cm	8 x 1011W-cm
Loss Tangent	0.0015	0.0035

Comparison, BGO, CWO
Properties of scintillation crystals
Crystal	BGO	CWO
Item	Bi4Ge3O12	CdWO4
Effective  atomic number	75	65
Density  (g/cm³)	7.13	7.90
Decay  constant (ns)	300	5000
Light output  (%)	12	39
Maximum  emission wavelagth (nm)	480	540
Refractive  index	2.15	5.25
Sensitivity  to moisture	None	None
Cleavage	None	Yes
Attenuation coefficient	X-ray  150 KeV	9.84	7.64
(cm-1)	Y-ray  511 KeV	0.955	0.856
	Characteristics	Application
GSO	Short decay time	High performance
Positron CT
BGO	Better absorption of	Positron CT
Radioactive rays	Detection of high energy
Because of its large	Partidle in the field of
Effective atomic number	Fundamental physics
CWO	Large light output, which enables the use of silicon photo diode	X-ray CT