There are numerous helpful issues you are able to do with a Raspberry Pi Pico (opens in new tab), as our itemizing of the most effective Raspberry Pi Initiatives (opens in new tab) underlines. Nevertheless, right here’s one we admit we’d by no means considered: detecting radiation. Physicist Matthias Rosezky, AKA Nuclear Phoenix (opens in new tab), whose work has additionally been lined by Hackaday (opens in new tab), has written up an in depth account of constructing a DIY gamma-ray spectrometer in IEEE Spectrum (opens in new tab).
The gadget acts a little bit like a Geiger counter however is extra delicate and may determine the precise mixture of isotopes that makes the detector click on. Rosezky described the Pico because the ‘pure alternative’ for a microcontroller when creating this undertaking. He bought a small sodium iodine crystal from eBay for $40 and mixed it with a silicon photomultiplier. All this was related to a provider board, into which the Pi Pico was inserted. A gamma ray produces an electron with proportional power within the crystal, which excites the atoms because it strikes by the construction. This causes photons – mild – to be emitted, and by counting the photons, you may know the power of the gamma ray.
Often known as the Open Gamma Detector (opens in new tab), the intention behind the undertaking is to maintain the value down, because the units can price over $1,000 if bought from a lab provider. Measuring simply 6cm x 6cm (2.3in sq.), the customized detector PCB makes up many of the gadget’s space, because the Pico itself slots into it.
The photons that come out of the crystal are amplified and measured by a photomultiplier, which releases a voltage. That is then elevated to a detectable degree utilizing a non-inverting operational amplifier, which is picked up by a peak detector and pulse discriminator related to the microcontroller. Any detections are despatched to a recording voice over USB and can even make an audible CLICK sound as a warning. No exterior sound {hardware} is required.
Programming comes through the Arduino IDE. Rosezky wrote his personal library to calibrate the detector, and all code, in addition to specs for the provider board, can be found on GitHub (opens in new tab), together with a pattern internet app that plots spectra.
One notable situation with the Pico is a differential non-linearity error, imagined to be one thing to do with the board’s capacitors, that results in 4 (out of 4,096) enter channels being rather more delicate than the remaining. Rosezky makes use of the easy answer of discarding the indicators from these channels in order to not have spikes that skew the readings and hopes it should get fastened in {hardware} quickly.