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SI-19BGM Possibly the smallest end-window GM tube in the world?
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- Mr Blinky
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SI-19BG (M) | SI19BGM | СИ19БГМ - Tiny end-window Geiger Muller Tube
I received this today after waiting for it to arrive for a couple of weeks. Purchased from Ukraine (via eBay). Not only is it tiny, it is the most expensive GM tube I have bought yet per gram of weight! And it appears to work okay. Sensitive to Gamma and Beta. This tube really is remarkably small. The end window must be no larger than 6mm diameter and the whole thing is only 20mm in length. It's not sensitive and for the couple of minutes I had it on test, the background was about 4cpm and it went nuts with Am-241 being held close to the window.
The specifications are a bit sketchy and I can't find a datasheet with the proper specs. These are from the ebay listing:
SI-19BGM geiger tube is designed to detect betta, gamma
Sensitivity Radiation 1000-1500 Pulses/s/R/h
Plateau Inclination 0.25%/V
Working Voltage 360-440V
Maximum registering range 900 Roentgen/hour
Length 20mm
Diameter 9.3mm
Weight 4 grams
At first I tried it with about 400v (~405v) and a 4.7M resistor, but it was counting too much (avalanching?). I changed the anode resistor for a 10M resistor and that seemed to calm it down quite a lot. I think this is probably better in the 380-390v range, and I'll test that at some point.
You can download hi-res pictures here.
The next images show it next to a CR2032 battery and an Am-241 button.
Archived from radmon.org - originally posted 22/11/2024
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