If you’re a radiation enthusiast, there’s probably a Geiger counter around you. Although Geiger counters can be used to detect the amount of radiation present, three types of radiation can also be distinguished through some techniques( α、β and γ), However, their use in identifying radioactive materials is limited. To do this, you need a different instrument called a gamma ray spectrometer.
Spectrometers are usually expensive and complex instruments for radiation professionals. But not necessarily: Physics enthusiast [nuclear Phoenix] has designed a handheld gamma spectrometer, which is easy to assemble and should meet the budget of amateurs. It outputs spectra that can be compared with reference data to identify specific elements.
The scintillator and sensor are wrapped with black tape to block the ambient light.
The core of the device is a scintillation crystal, such as thallium doped sodium iodide, which can convert incident gamma rays into visible light. The generated flash is detected by a silicon photomultiplier tube, and its output is amplified and processed, and then digitized by the ADC of raspberry PI Pico. Pico calculates the spectrum of the pulse and generates a graph, which can be stored on its on-board flash memory or downloaded to the computer.
[nuclearfoenix] has written a convenient program to help analyze the output data and make all design files open source. The hardest part to find will be scintillating crystals, but they occasionally appear on auction sites such as eBay. We have previously launched a gamma spectrometer based on Arduino; If you’ve always wanted to launch your own scintillator, you can do the same.