Best enclosure for mounting geiger tube outdoors

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2 years 10 months ago #4603 by Simomax
I would just stick with a SBM-20 or something similar for background monitoring. From what I have seen the glass tubes are usually not as sensitive as the SBM-20 unless you want to throw some money at it and then you are going into the realms of 'exotic' GM tubes which can often require a much higher voltage and may not work with some of the cheaper counters.

If you want something more sensitive than a SBM-20 or equivalent then look at the SBM-19 or SI-22G but bear in mind these are much larger than the SBM-20.

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2 years 10 months ago - 2 years 10 months ago #4612 by nzoomed

I would just stick with a SBM-20 or something similar for background monitoring. From what I have seen the glass tubes are usually not as sensitive as the SBM-20 unless you want to throw some money at it and then you are going into the realms of 'exotic' GM tubes which can often require a much higher voltage and may not work with some of the cheaper counters.

If you want something more sensitive than a SBM-20 or equivalent then look at the SBM-19 or SI-22G but bear in mind these are much larger than the SBM-20.

I might look into those tubes, but ive already ordered an SBM 20.
I might in future swap out tubes and compare readings, but at least most stations are using SBM20 for comparison.
BTW, did you get my PM?
Last edit: 2 years 10 months ago by nzoomed.

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2 years 10 months ago #4613 by Simomax
Hi nzoomed,

Yeah, I got your PM. I replied last night.

Use your SBM-20 for now. Get up and running with it and go from there. Maybe try a different tube in the future. They are fun to experiment and play about with. It's always good to check the specs of a tube before you buy it as some require quite high voltages to run, so the small cheap MCU type counters, like my GC-10 won't go higher than 700-800v. The DiyGeiger runs to about 950v.
There are some more exotic tubes that can require 1200v or even 1600v as I saw for one tube.

Generally the SBM-20 style (metal can with terminals on each end) are below 500v so good to run on the cheap counters. The LND712 is a good little tube for gamma (y), beta (b) and alpha (a) though a little pricey at ~£75 and is slightly less sensitive than the SBM-20 to y & b. The SBT-10A and SBT-11A are good quite sensitive y, b & a tubes. You can often find them on ebay. The 10A for ~£45 and the 11A for ~£25. They are essentially the same tube but the 10A has 10 anodes and the 11A has only 4 anodes. Its kinda useless using these tubes outdoor to pick up alpha because they will need covering from the elements and thus block alpha.

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2 years 10 months ago #4614 by nzoomed

Hi nzoomed,

Yeah, I got your PM. I replied last night.

Use your SBM-20 for now. Get up and running with it and go from there. Maybe try a different tube in the future. They are fun to experiment and play about with. It's always good to check the specs of a tube before you buy it as some require quite high voltages to run, so the small cheap MCU type counters, like my GC-10 won't go higher than 700-800v. The DiyGeiger runs to about 950v.
There are some more exotic tubes that can require 1200v or even 1600v as I saw for one tube.

Generally the SBM-20 style (metal can with terminals on each end) are below 500v so good to run on the cheap counters. The LND712 is a good little tube for gamma (y), beta (b) and alpha (a) though a little pricey at ~£75 and is slightly less sensitive than the SBM-20 to y & b. The SBT-10A and SBT-11A are good quite sensitive y, b & a tubes. You can often find them on ebay. The 10A for ~£45 and the 11A for ~£25. They are essentially the same tube but the 10A has 10 anodes and the 11A has only 4 anodes. Its kinda useless using these tubes outdoor to pick up alpha because they will need covering from the elements and thus block alpha.

Oh, yes I see it thanks :)

Im going to stick with the SBM-20 for now I think, but may set up another station in the area for a friend with a different tube.
Just waiting to get my kits from DIY Geiger.
Im also going to build a handheld unit using a philips 18504. I believe its basically near identical specs to the LND712.
Your right about using alpha tubes outdoors, its almost a pointless exercise. Iodine 131 is both a strong gamma and beta emitter, so I would expect this would trigger off readings in the event of a nuclear event anyway.
Ive been watching the stations in europe after the recent event in Russia, but doesnt seem to have made any noticeable impact on readings from what i can see. I do believe that iodine 131 has been detected in norway, but its short half life does not give it much time to spread and be detected.

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2 years 10 months ago #4615 by FSM19
Common data sheets that I have seen give the inherent count rate for the SBM20 as 1cps, which seems awfully high, possibly a worst case.

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2 years 10 months ago - 2 years 10 months ago #4616 by nzoomed

Common data sheets that I have seen give the inherent count rate for the SBM20 as 1cps, which seems awfully high, possibly a worst case.


that is a pretty high count!
I think your right, would have to be worst case.
Last edit: 2 years 10 months ago by nzoomed.

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