I phone geiger counter - tested by a lab

[Shannow]

Flipping around the net after work, I found this article (2014), on the radiation detecting apps that were all the rage back in 2014...well they were for me, I had an Iphone 4S, the app, some black electrical tape and thoriated tungsten tig tips.

This is the Australian ANSTO, testing the apps themselves

http://www.ansto.gov.au/AboutANSTO/MediaCentre/News/ACS049898

Highest background I saw with it was tombstone Arizona on our last trip over there.

 

[SR5]

Interesting, I would have doubted the claims until I saw it was checked and verified by ANSTO (Australian Nuclear Science and Technology Organimation). I've worked with those guys before, they are very precise.

The detector is the CMOS (complementary metal-oxide-semiconductor) chip in the camera, after light has been blocked out by black tape.

 

[gathermewool]

I'd be careful equating CPM to dose equivalent. You don't know what all of the radiation sources are, so the counts could be anything from radioactive fallout to cosmic rays to naturally occurring.

That is, if your setup is even detecting alpha, beta and gamma. Well, hopefully you're not detecting any alpha, but I can see how beta might be blocked if there is no beta-permiable window in the device. If that were the case, your counts are just from gamma.