range of geiger counter

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empleat
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range of geiger counter

Postby empleat » Tue May 28, 2019 12:19 pm

What is maximum range for detecting gamma radiation with geiger counter ?

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mightyohm
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Re: range of geiger counter

Postby mightyohm » Tue May 28, 2019 12:48 pm

It will depend on the tube you decide to use. The datasheet for the SBM-20 is here:

https://www.gstube.com/data/2398/

It shows 0.014 - 144 mR/hr but I haven't verified this.

empleat
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Re: range of geiger counter

Postby empleat » Tue May 28, 2019 1:34 pm

I should have specified my question, from which distance can geiger counter detect radiation. I know it use some tube, with which you have to sweep around object. But there are some detector that work from long range right ? What is maximum range for detecting radiation ?

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Re: range of geiger counter

Postby mightyohm » Tue May 28, 2019 8:22 pm

That’s a difficult question to answer as it depends on the source you are trying to measure. Can you provide more details?

empleat
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Re: range of geiger counter

Postby empleat » Wed May 29, 2019 5:22 am

I am just interested, i am layman. Humor me, theoretically what can be maximum range for detection gamma radiation, if there were some irradiated area, like radiation pocket, or some object on the ground. What could be maximum range to detect it theoretically, it hasn't to be accurate. Also in what could me minimum range you have to be from the object to detect it. Perhaps in some situation it would require to be very close. And i am interested only in scenario, with gamma radiation of deadly dose. So lets say it would be irradiated highly.

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mightyohm
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Re: range of geiger counter

Postby mightyohm » Thu May 30, 2019 9:18 am

The intensity of radiation measured at a distance from a radioactive source falls with the square of the distance from the source. This is called the inverse square law: https://www.nde-ed.org/GeneralResources ... areLaw.htm

A really powerful source will be measurable a considerable distance away, while a faint source would require the detector to be relatively close. Most sources you are likely to encounter day to day will require the Geiger counter to be within a few inches of the source, although with long averaging periods you should be able to see a noticeable increase in background a foot or two away. It depends on the strength and type of the source. Any objects in between you and the source will cause the readings to drop much faster because they will shield a portion of the radioactivity.

empleat
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Re: range of geiger counter

Postby empleat » Sat Jun 01, 2019 10:23 am

I found that 1000 rad is almost invariably fatal. But i don't know per hour, or per second. Also i don't know from which distance. So i just ask simply. Can you detect deadly dose of radiation from safe distance, for example 1000 rad, the type of radiation which would be fatal in couple of seconds ?

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Re: range of geiger counter

Postby mightyohm » Mon Jun 10, 2019 3:22 pm

Again, it is very hard to say because it depends on the nature of the radiation, the difficulty of interpreting the results, and what is considered "safe". It would be very difficult to use the kit safely in an area with that level of radiation. The kit is not intended to be used for this purpose. It is for educational purposes only. Please buy a professionally calibrated Geiger counter for any application involving potential hazards.