had little success last month detecting radioactivity with my Nikon D90, but I found that a Logitech C270 webcam easily picked up alpha particles and beta particles from a variety of natural and artificial sources. I was hoping to use this webcam in the lab to monitor radioactivity, but its sensitivity was too low, mainly because of the small sensor. Even so, it's an interesting way to gain insight into the different types of radioactivity.
Although a webcam can detect high-energy particles without modification, it's necessary to modify it by removing the glass protective filter on the sensor to get maximum efficiency for low-energy particles such as alphas. Removing the filter also makes the webcam sensitive to infrared and ultraviolet light. In some older webcams, the filter and the protective glass over the sensor were separate, which made modifying them for infrared easy. In the C270, they are combined, which makes it more difficult. But ... it's not impossible.