Letter Re: Android Geiger Counter

Thanks for the reference to the $30 android counter; I bought one!

Also, note that Radioactivity Counter is an Android ap that I have used that detects gamma radiation just using the app; there’s no external devices needed!

You’re wondering how? You tape over the camera lens and the camera itself detects gamma radiation sensitivity depending on phone models. I’ve used it, and it works. – M.R.