SBM-20
The SBM-20 is the quintessential Soviet Geiger–Müller tube from the 1970s to the 1990s
Pictured left is an older, original style SBM-20 tube from the 1970's. Center is a more modern version from around the 1990's. Right is the slightly shorter SBM-20U variant with only one end cap and the anode exposed.
Specs:
- Temperature range: -60°C to +70°C
- Operative Voltage: 350V min 400V typ 475V max
- Initial Voltage: 260V min 320V max
- Plateau length: 100V min
- Plateau slope: 0,1%/V max
- Dead time: 190 uS min (@ 400V)
- Capacitance: 4,2 pF
- Life: 20 billion pulses
- Anode resistor: 4.7 MegaOhm
- Working range: 0.004-40 μR/s = 0.014-144 mR/h
- Gamma Ra226 sensitivity: 29 cps/mR/h
- Gamma Co60 sensitivity: 22 cps/mR/h
- Inherent Background: 1 cps
- Gas filling: Neon + Bromine + Argon
- Stainless steel cathode
- External length: 108mm
- Effective tube length: 90mm
- External diameter: 11mm max
- Effective tube diameter: 9.5mm
- Wall density: 40 mg/cm^2
- Wall thickness: 0.05mm
- Weight: 10 g
CV2247
Halogen quenched Gamma radiation detector with neoprene sheath for portable use.
The CV2247 Geiger–Müller tube was used in the 'British Contamination Meter No. 1'. The construction is a glass tube with a thick neoprene rubber protection boot over the tube. The connector is proprietary to the British Contamination Meter No. 1
Specs:
- Threshold voltage (at 20°C): 315 to 375 V
- Operating voltage (at 20°C): 355 to 415 V
- Plateau slope (per volt): 0.07% avg, 0.15% max
- Plateau length: 150 V avg, 90 V min
- Operating temperature range: -55 to +50°C
- Useful life: > 109 counts
- Mmeasures 125x32mm
