This device from AlexRH really caught our eye: the RH Electronics Nuclear Pioneer Multichannel Analyzer (MCA) Gamma Spectrometer. Based on the Teensy 3.5, the MCA can function as both a gamma ray spectrometer and a scintillation counter survey meter.

Gamma spectrometers work by detecting gamma energy from radioactive decay via a scintillation probe. The MCA can detect radioactive elements and automatically identify isotopes on a range of 32keV-3000keV.

With high-voltage regulated power module featuring an adjustable output of 600-1000V, the device can be connected to an external photomultiplier tube, plus has a 400V regulated power supply for an internal Geiger counter.

Read more about its capabilities on the RH Electronics web site, or check out the video below for a detailed demonstration.