You already have your smartphone, most probably: https://phys.org/news/2014-06-smartphone-detector-app-positive.html https://phys.org/news/2014-06-smartphone-de

You already have your smartphone, most probably: https://phys.org/news/2014-06-smartphone-detector-app-positive.html https://phys.org/news/2014-06-smartphone-detector-app-positi... Smartphone cameras are sensitive to radiation (radiation produces additional spurious reading in camera sensors - additional noise over thermal one) and it is possible to use these cameras to more or less accurately measure radiation levels.