The Hottest Spark Plugs Were Actually Radioactive

In the middle of the 20th century, the atom was all the rage. Radiation was the shiny new solution to everything while being similarly poorly understood by the general public and a great deal of those working with it.

Against this backdrop, Firestone Tire and Rubber Company decided to sprinkle some radioactive magic into spark plugs. There was some science behind the silliness, but it turns out there are a number of good reasons we’re not using nuke plugs under the hood of cars to this day.

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Meter Mods Make Radioactive Prospecting More Enjoyable

While we often get a detailed backstory of the projects we cover here at Hackaday, sometimes the genesis of a build is a bit of a mystery. Take [maurycyz]’s radiation survey meter modifications, for instance; we’re not sure why such a thing is needed, but we’re pretty glad we stumbled across it.

To be fair, [maurycyz] does give us a hint of what’s going on here by choosing the classic Ludlum Model 3 to modify. Built like a battleship, these meters would be great for field prospecting except that the standard G-M tube isn’t sensitive to gamma rays, the only kind of radiation likely not to be attenuated by soil. A better choice is a scintillation tube, but those greatly increase the background readings, making it hard to tease a signal from the noise.

To get around this problem and make rockhounding a little more enjoyable, [maurycyz] added a little digital magic to the mostly analog Ludlum. An AVR128 microcontroller taps into the stream of events the meter measures via the scintillation tube, and a little code subtracts the background radiation from the current count rate, translating the difference into an audible tone. This keeps [maurycyz]’s eyes on the rocks rather than on the meter needle, and makes it easier to find weakly radioactive or deeply buried specimens.

If you’re not ready to make the leap to a commercial survey meter, or if you just want to roll your own, we’ve got plenty of examples to choose from, from minimalist to cyberpunkish.

A piece of perovskite crystal

Perovskite Solar Cell Crystals See The Invisible

A new kind of ‘camera’ is poking at the invisible world of the human body – and it’s made from the same weird crystals that once shook up solar energy. Researchers at Northwestern University and Soochow University have built the first perovskite-based gamma-ray detector that actually works for nuclear medicine imaging, like SPECT scans. This hack is unusual because it takes a once-experimental lab material and shows it can replace multimillion-dollar detectors in real-world hospitals.

Current medical scanners rely on CZT or NaI detectors. CZT is pricey and cracks like ice on a frozen lake. NaI is cheaper, but fuzzy – like photographing a cat through steamed-up glass. Perovskites, however, are easier to grow, cheaper to process, and now proven to detect single photons with record-breaking precision. The team pixelated their crystal like a smartphone camera sensor and pulled crisp 3D images out of faint radiation traces. The payoff: sharper scans, lower radiation doses, and tech that could spread beyond rich clinics.

Perovskite was once typecast as a ‘solar cell wonder,’ but now it’s mutating into a disruptive medical eye. A hack in the truest sense: re-purposing physics for life-saving clarity.

Food Irradiation Is Not As Bad As It Sounds

Radiation is a bad thing that we don’t want to be exposed to, or so the conventional wisdom goes. We’re most familiar with it in the context of industrial risks and the stories of nuclear disasters that threaten entire cities and contaminate local food chains. It’s certainly not something you’d want anywhere near your dinner, right?

You might then be surprised to find that a great deal of research has been conducted into the process of food irradiation. It’s actually intended to ensure food is safer for human consumption, and has become widely used around the world.

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Desk Top Peltier-Powered Cloud Chamber Uses Desktop Parts

There was a time when making a cloud chamber with dry ice and alcohol was one of those ‘rite of passage’ type science projects every nerdy child did. That time may or may not be passed, but we doubt many children are making cloud chambers quite like [Curious Scientist]’s 20 cm x 20 cm Peltier-powered desktop unit.

The dimensions were dictated by the size of the off-the-shelf display case which serves as the chamber, but conveniently enough also allows emplacement of four TEC2-19006 Peltier cooling modules. These are actually “stacked” modules, containing two thermoelectric elements in series — a good thing, since the heat delta required to make a cloud chamber is too great for a single element. Using a single-piece two stage module simplifies the build considerably compared to stacking elements manually.

To carry away all that heat, [Curious Scientist] first tried heatpipe-based CPU coolers, but moved on to CPU water blocks for a quieter, more efficient solution. Using desktop coolers means almost every part here is off the shelf, and it all combines to work as well as we remember the dry-ice version. Like that childhood experiment, there doesn’t seem to be any provision for recycling the condensed alcohol, so eventually the machine will peter out after enough vapor is condensed.

This style of detector isn’t terribly sensitive and so needs to be “seeded” with spicy rocks to see anything interesting, unless an external electric field is applied to encourage nucleation around weaker ion trails. Right now [Curious Scientist] is doing that by rubbing the glass with microfiber to add some static electricity, but if there’s another version, it will have a more hands-off solution.

We’ve seen Peltier-Powered cloud chambers before (albeit without PC parts), but the “dry ice and alcohol” hack is still a going concern. If even that’s too much effort, you could just go make a cup of tea, and watch very, very carefully.

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Could Space Radiation Mutate Seeds For The Benefit Of Humanity?

Humans have forever been using all manner of techniques to better secure the food we need to sustain our lives. The practice of agriculture is intimately tied to the development of society, while techniques like selective breeding and animal husbandry have seen our plants and livestock deliver greater and more nourishing bounty as the millennia have gone by. More recently, more direct tools of genetic engineering have risen to prominence, further allowing us to tinker with our crops to make them do more of what we want.

Recently, however, scientists have been pursuing a bold new technique. Researchers have explored using radiation from space to potentially create greater crops to feed more of us than ever.

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Memristors Are Cool, Radiation-resistant Memristors Even Moreso

Space is a challenging environment for semiconductors, but researchers have shown that a specific type of memristor (the hafnium oxide memristor, to be exact) actually reacts quite usefully when exposed to gamma radiation. In fact, it’s even able to leverage this behavior as a way to measure radiation exposure. In essence, it’s able to act as both memory and a sensor.

Being able to resist radiation exposure is highly desirable for space applications. Efficient ways to measure radiation exposure are just as valuable. The hafnium oxide memristor looks like it might be able to do both, but before going into how that works, let’s take a moment for a memristor refresher.

A memristor is essentially two conductive plates between which bridges can be made by applying a voltage to “write” to the device, by which one sets it to a particular resistance. A positive voltage causes bridging to occur between the two ends, lowering the device’s resistance, and a negative voltage reverses the process, increasing the resistance. The exact formulation of a memristor can vary. The memristor was conceived in the 1970s by Leon Chua, and HP Labs created a working one in 2008. An (expensive) 16-pin DIP was first made available in 2015.

A hafnium oxide memristor is a bit different. Normally it would be write-once, meaning a negative voltage does not reset the device, but researchers discovered that exposing it to gamma radiation appears to weaken the bridging, allowing a negative voltage to reset the device as expected. Exposure to radiation also caused a higher voltage to be required to set the memristor; a behavior researchers were able to leverage into using the memristor to measure radiation exposure. Given time, a hafnium oxide memristor exposed to radiation, causing it to require higher-than-normal voltages to be “set”, eventually lost this attribute. After 30 days, the exposed memristors appeared to recover completely from the effects of radiation exposure and no longer required an elevated voltage for writing. This is the behavior the article refers to as “self-healing”.

The research paper has all the details, and it’s interesting to see new things relating to memristors. After all, when it comes to electronic components it’s been quite a long time since we’ve seen something genuinely new.