Warwalking For Radiation

Can’t find a recently updated survey of radioactivity in your neighborhood? Try [Hunter Long]’s DIY scintillation counter warwalking rig. (Video also embedded below.) What looks like a paint can with a BNC cable leading to an unassuming grey box is actually a complete kit for radiation surveying.

Inside the metal paint can is a scintillation counter, which works by attaching something that produces light when struck by ionizing radiation on the end of a photomultiplier tube, to make even the faintest hits “visible”. And the BNC cable leads to a Raspberry Pi, touch screen, GPS, and the high-voltage converters needed to make the photomultiplier do its thing.

The result is a sensitive radiation detector that logs GPS coordinates and counts per second as [Hunter] takes it out for a stroll. Spoilers: he discovers that some local blacktop is a little bit radioactive, and even finds a real “hot spot”. Who knows what else is out there? With a rig like this, making a radiation map of your local environment is a literal walk in the park.

[Hunter] got his inspiration for the paint-can detector from this old build by [David Prutchi], which used a civil-defense Geiger counter as its source of high voltage. If you don’t have a CD Geiger detector lying around, [Alex Lungu]’s entry into the Hackaday Prize builds a scintillation detector from scratch.
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Tearing Down A Darkroom Relic For Buried Treasure

If your goal is to harvest unique parts from defunct devices, the further back in time you go, the better the pickings stand to be. At least that’s what [Kerry Wong] discovered during his tear-down of a darkroom color analyzer from the early 1980s.

For readers whose experience with photography has been solely digital, you need to understand that there once was a time when images were made with real cameras on real film, and serious amateurs and pros had darkrooms to process the film. Black and white processing was pretty straightforward in terms of chemistry — it was just developer, stop, and fixing. Color processes were much trickier, and when it came to enlarging your film onto color photo paper, things could get really complicated. [Kerry]’s eBay find, a Besler PM1A color analyzer, was intended to help out in the color lab by balancing the mix of cyan, blue, and yellow components in the enlarger.

The instrument, which no doubt demanded a princely sum back in the day, is actually really simple, with the object of [Kerry]’s desire, a PM1A photomultiplier tube and its driver, being the only real find.  Still, it’s an interesting teardown, and we’re eager to see what [Kerry] makes of the gem. A muon detector, perhaps? An X-ray backscatter machine? Or perhaps repeating his old speed of light experiments is on the docket.

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Arduino Does Hard Science

We don’t know why [stoppi71] needs to do gamma spectroscopy. We only know that he has made one, including a high-voltage power supply, a photomultiplier tube, and–what else–an Arduino. You also need a scintillation crystal to convert the gamma rays to visible light for the tube to pick up.

He started out using an open source multichannel analyzer (MCA) called Theremino. This connects through a sound card and runs on a PC. However, he wanted to roll his own and did so with some simple circuitry and an Arduino.

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