Geigers on a plane

[Thomas] took a Geiger counter he built on a plane. Why? Because he can, much to the chagrin of airport security.

[Thomas]’ Geiger counter is built around an old Russian SBT-10A detector containing ten separate Geiger tubes. This tube was connected to a circuit containing a LiPo battery, a few high-voltage components, and an audio jack connected to the tubes themselves. When alpha, beta, or gamma radiation hits one of the Geiger tubes, an enormous click is sent to the audio jack and into the microphone jack of a small netbook.

Right after boarding a plane in Dublin, [Thomas] booted up his computer, started recording in Audacity, plugged in his Geiger counter, and stored his experiment safely in the overhead compartment. After landing in Prague a few hours later, [Thomas] saved the 247 MB .WAV file and began working on a way to convert clicks in an audio track into usable data.

The audio output on the Geiger counter overloaded the mic input on his netbook, making ‘event detection’ very easy with a small C app. After plotting all the data (seen above), [Thomas] had a complete record of the radiation on his 2-hour flight.

Because there was far less atmosphere to absorb cosmic radiation, [Thomas]’ radiation dose was 9.1 microsieverts. Much more than at sea level, but nothing even air crews need to worry about.

Detecting cosmic rays with 18 Geiger tubes

What do you do if you have 18 Geiger tubes lying around? [Robert] had an interesting idea to build a cosmic ray detector and hodoscope to observe the path cosmic rays take while flying through his lab.

[Robert]’s cosmic ray detector works by detecting the output 9 Geiger tubes on the y-axis and 9 Geiger tubes on the x-axis with a coincidence circuit. When a cosmic ray flies through the detector, it should trigger two tubes simultaneously. By graphing which of the two tubes were triggered on an array of 81 LEDs, [Robert] not only knows when a cosmic ray is detected, but where the cosmic ray was.

The detectors do pick up a little background radiation, but thanks to [Robert]’s coincidence circuit, he can be fairly certain that what he’s recording are actually high-energy cosmic rays.

Before building the 9×9 hodoscope, [Robert] built a similar drift hodoscope that simply plots the path a cosmic ray takes through an array of Geiger tubes. You can check out videos of both these cosmic ray detectors after the break.

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Making music with radiation

[Jeff Keyser] from mightyohm.com got a chance to show off this interesting take on ambient music. He’s using his geiger counter kit to detect beta and gamma radiation. This then sends a pulse down the line to an Arduino to turn it into a musical note. The geiger counters put out a 1.ms 3v pulse though, so he first has to run this through a 74Ls04, which spits out the 5V the arduino wants. He’s admittedly no musician, but you can hear in the video it sounds fine. Especially considering they are all just C in different octaves. Those of us that are musicians probably would have gone with a B#.

The ambient noise is interesting, but when you realize it is due to radioactive decay, it becomes somehow more attention getting. We often forget about the invisible world around us. He even drops a few Uranium marbles onto the geiger counters to spice things up.

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Measure radiation with military surplus

It’s really amazing what you can find at military surplus shops. [David] just built a radiation detector out of a DT-590A scintillation probe originally made to test if Air Force bases were contaminated with Plutonium. Who says nothing good came out of massive nuclear arsenals?

DT-590A / PDR-56 Gamma ray probes were made obsolete by the US Air Force a few years ago and they’re trickling into military surplus stores around the country and the Internet. [David] found the manual for this probe and put together a little circuit to drive this x-ray sensor. The build uses an ammeter as a simple dial, and includes a piezo speaker for the prerequisite Geiger counter ‘clicks.’

[David] also threw up a post on converting this x-ray probe into a general purpose Gamma probe, effectively making it a Geiger counter for the really dangerous radiation. You could always use your smart phone for the same task, but recycling military hardware imparts a good bit of geek cred.

Turn your camera phone into a Geiger counter

Next time you’re waiting in the security line in an airport, why don’t you pull out your smartphone and count all the radiation being emitted by those body scanners and x-rays? There’s an app for that, courtesy of Mr. [Rolf-Dieter Klein].

The app works by blocking all the light coming into a phone’s camera sensor with a piece of tape or plastic. Because high energy radiation will cause artifacts on the CMOS camera sensor inside the phone, radiation will be captured as tiny specks of white light. The title picture for this post was taken from a camera phone at the Helmholtz Research Center in Munich being bathed in 10 Sieverts per hour of Gamma radiation from the decay of Cesium-137.

We have to note that blips of ‘bad data’ from a CMOS camera sensor aren’t unusual. These can come from electrical weirdness in the sensor itself or even the heat from the battery. [Rolf]’s app takes a reading of the noise floor and subtracts it from the counter. Radioactive decay resulting in Beta particles such as the Potassium-40 in bananas or the Uranium in granite counter tops don’t really register, although [Rolf] did have some success with Potassium chloride and a long measurement time. Still though, it’s a really cool way to turn a phone into a tricorder.

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Radiation sensor shield for the Arduino

The [Libelium] team wanted to help people in Japan measure radiation in their surroundings following the nuclear accident in Fukushima. Because of the affordability and seeming ubiquity of the Arduino platform, they have been hard at work this last month trying to get their Geiger counter sensor board for an Arduino out the door. We think they’ve done a remarkable job.

A Geiger tube is a remarkably simple device, but getting the part can be a fairly expensive proposition. Thankfully, [Libelium] has already tested and verified a number of tubes from different manufacturers – very helpful if you don’t want to be tied down to one specific component.

This looks like this is just the sort of thing that the folks at [Seed Studio] wanted for an open hardware radiation detector, and [Libelium] has already shipped their first batch to the Tokyo Hackerspace. It’s good to know that help is going where it’s needed.

Video of the sensor board being tested after the break.

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Geiger counter built in an Ohmmeter enclosure

Here’s a Geiger Counter that makes itself at home inside of an old Ohmmeter (translated). [Anilandro] set out to built this radiation detector in order to learn how they work. Like other diy Geiger Counter builds we’ve seen, this project assembles a circuit to interface with a gas-filled tube which serves as the detector. [Anilandro] takes a few paragraphs to discuss how this works; the Geiger tube is basically a capacitor whose electrical characteristics change as an ionizing particle passes through it.

Once he had the theory worked out he scavenged some parts to use. A broken emergency light donated its transformer to provide the high voltage needed. The rest of the circuit was built on some protoboard, and a speaker was added to output the clicking noises that have become a familiar part of the detector hardware. The tube itself is housed in a wand that attaches to the base unit through a cable. Check out some test footage of the finished unit after the break.

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