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artis

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Let's say I have a decent gain and sensitivity GM tube type detector some distance away from my point source. Let's say I don't know the type of isotope giving off the radiation , all I get are certain amount of "clicks" that represent the amount of radiation hitting my tube minus the ones that don't get counted due to the limited efficiency of the tube.

So would I then knowing the efficiency of my detector could estimate the total radioactivity of the source by then measuring the distance from the source and using that distance as radius and then integrating over an imaginary sphere around the source where the distance from the source to my detector is the radius. I guess I would also need to know the size of my tube in order to know the size of the surface "patches" that I have to integrate over the sphere surface.

Is this the only method to approximate the total count rate per second of the source in my described situation?

Could I in any way also know the isotope I'm looking at solely based on this information (distance to source, integrated total surface activity) ? It seems I couldn't.