Tube: STS-5 (СTC-5) Geiger tube


STS-5_Geiger_tube_1 STS-5_Geiger_tube_2 geiger_tubes_comparison


Old generation Geiger-Muller tube, for gamma and hard beta radiation. It is the precursor of the SBM-20, which it resembles in many of its technical parameters, including size and sensitivity.

Notes on sensitivity:

This is a moderately sensitive tube, and this is not bad for a tube as old as the STS-5. Some of these were manufactured in the 60’s. The Russian tubes carry a year identifier, and newer models include the month as well, in the form MMYY or YYMM. It’s relatively small size, makes it a convenient choice as a radiation detection element in handheld dosimeters and DIY circuits, however given its age, alternatives should be considered. The following chart shows the average of the background readings over a period of 24 hours and each point in the chart was computed using another average of 60 independent, consecutive measurements. The dosimeter used to take the measurements has 1 minute resolution.
Background readings: 18CPM for a background radiation level of 0.12uSv/h


Gamma radiation sensitivity (Cs137): MED – 0.28mkR∙s-1
Operating Voltage Range (volts): 360 – 440V
Starting voltage (volts): 280 – 330V
Geiger plateau length: not less than 80 V
Plateau slope: no more than 0.125%/V
Maximum natural background : 27 pulses / min or 0.45/s
Load resistance : 5…10 MOhm
Allowable stray capacitance of input circuits : 10 pF
Transit capacitor : 7…10 pF
Operation temperature range: -40 to +50C
The maximum operating MED 2500 s-1, 30mkR∙s-1,k.n.± 20%
The maximum permissible MED dose – at least 50R∙ h-1
Length: 110 mm
Diameter: 12 mm
Weight: 8g


STS5 on GStubes

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