There are many ways to measure radioactivity level, semiconductor detectors sense interactions between ionizing radiation and p-n junction. Because in hobbyist area most popular are Geiger-Muller based detectors (in short: not a semiconductor but lamp based devices), I think it's a cool idea to take a look at this approach.
In this post I will present such home-made sensor and a set of software to parse collected results.
Picture below presents circuit of the sensor that I made, it consist of a photodiode that acts as a sensor, transimpedance amplifier and "regular" amplifier. I've selected op-amps that has little input noise.
Changes that I made during testing the device, that are not presented on the diagram:
- D1 is BPW34
- U1 is OPA657U
- U2 is OPA656U
- 2p capacitor is connected in parallel with R6
- 820k resistor is connected between U2 out and BNC socket.
Below is visible sensor in enclosure and without it. Because the device is sensitive for background EMI and light noise, a metal housing is needed. To increase exposure of the sensor to the radiation, where it is, in the housing, a hole is made and just a tiny adhesive metal tape is covering it.
