Seeed looks for help developing an open source radiation detector

Seeed Studios, makers of the Seeeduino and fabricators of small-run PCB orders have put out a call to help develop an open source radiation detector. Will it be of any help to people in the area of Japan that is at risk? We really can’t say. But if you can lend some expertise with this, it can’t hurt. We’ve already seen a simple dosimeter project but this one sounds like it’s more on the level of a DIY Geiger counter. We know it’s possible, but the hacked together unit we saw back in 2007 had very little documentation and used parts that may be hard to come by.

The specific information needed is what type of sensor to use, what supporting circuits should be included, and what method is best to calibrate each unit. There’s a discussion going in the comment thread of that post which should be interesting to read even if you think you don’t have anything to add.

[Thanks Michael]

Comments

  1. cfox says:

    Wish I could be of some help.
    Solid idea though, good luck with finishing it. Hope it turns out to be useful.

  2. Whatnot says:

    They should just get one person in every decent sized town to put up a proper geiger counter and have it tweet the measurements every 10 to 15 minutes.
    Preferably set up on a stable hill with backup power and wifi or radio bursts copying the output too when internet is out, if need be using morse code.

  3. Nuclear war survival skills Chapter 10 – http://www.oism.org/nwss/s73p921.htm

    The Kearny Fallout Meter is an accurate and well tested device designed for civil defence that can be built by anyone. Let’s not reeinvent the wheel or anything…

  4. http://www.oism.org/nwss/s73p938.htm is the appendix which has the actual ‘how to build’ portion.

  5. Andrew says:

    essentially a geiger counter is an spark gap with a strong potential difference between the containing wall and the central electrode. the volume is filled with a gas with a cross section of interaction for ionizing particles.

    when an ionizing radiation splits a given molecule of gas the newly created charged particle pair and are split by the potential difference in the detector and fly towards their respective electrodes. the current generated by the moving charged particles is incredibly small, but measurable.

    short of growing your own CCDs or adapting units available on the market this is the only method I know of to detect radiation reliably.

    the main road blocks I can see in getting a decent open source detector would be ensuring the seal’s integrity (there doesn’t have to be a pressure difference, just a known gas), acquiring the selected gas, and most importantly calibration. I don’t know many people who keep known and dated radiation sources on hand.

  6. greg says:

    sparkfun has something that could be useful for some inspiration.

    http://www.sparkfun.com/products/9848

  7. l|_|GN|_|t says:

    Sparkfun sells geiger counters, but they all sold out in the past couple days, predictably

  8. Joe says:

    I’m not sure if many people on hack-a-day know about this website but they sell surplus components for cheap. And oh look, they happen to have Geiger counter kits on sale….

    http://goldmine-elec.com/

  9. Eman says:

    Andrew> couldn’t someone use a smoke detector as a crude radiation detector, then ?

  10. the_truth says:

    Interestingly enough, it may be possible to use the ionization chamber from a smoke detector for this one. The only real modification would be removal of the radio isotope, so that you would be able to detect ionization rather than the neutralization of said ionization due to smoke. for cost efficiency, it would be best to use a resistor/led ladder for your display. The only downside to the devices is the requirement of high voltage to detect the ionization. This is murder on batteries.

  11. Jeff says:

    Components for a radiation detector typically include a HV supply, preamp, shaping amp, and comparator (1MHz or better) depending on the detector because radiation events are much faster than the common audio signals. HV can be a simple C-W ladder with a HV filter at the end. Bias of course depends on the detector and how it is applied also. A G-M tube applies bias to the central wire and grounds the outer tube. When a pulse event occurs, the G-M enters a breakdown region where as the ion pairs move toward the respective cathode/anode, a multiplicative effect occurs, causing one large pulse that signifies paralysis of the detector. The pulse leaving the detector needs to be processed by a current sensitive preamplifier, which then needs to output a voltage pulse. An amplifier will then shape and increase the amplitude of the signal so that it will be able to trigger an event in a comparator. A counter then adds the events to a buffer, which can be coupled with a timer to give rate information. Lastly, a display then shows the count rate information either through some bouncing needle meter or some other output means. Calibration will require a radiation source. Cs-137 is the standard calibration source and is available in NRC exempt quantities of 1uCi to 10uCi from Spectrum Techniques in Oak Ridge, TN. There are several IEEE standards pertaining to the calibration and testing (N323 is one of them I think and there are an entire series of these).

  12. Reaper says:

    a DIY rad-hardened Geiger counter? Sounds awesome.

  13. Jeditalian says:

    i wanna geiger counter

  14. SquantMuts says:

    About homebrew geigercounters, would it be possible to replace the hard to get vacuum chamber with something more managable?

    What about an reverse biased large area diode? Like a monocrystalline solar cell? Make it completely dark, then detecting the small pulses of leakage in the PN junction? Every charged particle that would travel trough it would create a small jump in leakage, this could be detected by a high impedance low noise amplifier like a JFET input opamp or a BF862 based amplifier?

    Problem with such a setup would be to shield it from light but not from radiation. Alpha and beta particles are easely stopped so it would mostly detect gamma radiation.

    Anybody has any pitchblende uranium ore in their mineral collection to test it out? I think an americium based smoke detector would do it too. Remove the small gold matrix that encapsulates the source.

  15. Necromant says:

    They need to ask this guy for help: http://radiokot.ru/circuit/digital/measure/34/
    (sent that as a tip to HaD but it didn’t come through)

  16. SquantMuts says:

    Followup:

    I found this circuit using a PIN photodiode.

    http://www.maxim-ic.com/app-notes/index.mvp/id/2236

    A good sensitive diode would be the BPW34, it is cheap and easy to get.

  17. I’m amazed no one even looked/remarked on the kearny fallout meter – which is a circa 1970’s homebrew meter that was tested in a lab to be VERY PRECISE.

  18. HackerK says:

    Idea of using CCD and CMOS as sensors

    http://www.hps.org/publicinformation/ate/q8921.html

    Further research needs to be done here, as it could be a very low cost (and low voltage!) sensor device

  19. HackerK says:

    @Necromant Wow, that’s awesome work that Russia guy did!!!

  20. clnielsen says:

    everyone should research the kearney fallout meter

  21. asheets says:

    I agree with the posters pushing The Kearny Fallout Meter — considering what it is made of, it really fits in on HaD well.

    But if you insist, project #103 of this book: http://www.amazon.com/103-simple-transistor-projects-Kneitel/dp/B0007DWA6M . I’m sure it can be made with modern parts and smaller batteries.

  22. Apexys says:

    @ SquantMuts:
    It’s exactly what I was thinking.
    But why would you need pitchblende.
    If it works, you should get the 15-20 counts every minute from the background radiation.
    You could use an black cd-pen or something like this to cover the diode.
    I’m pretty sure it’ll work.

    apexys

  23. Gema says:
  24. On a related note my geiger counter is on twitter at twitter.com/geiger93933. In marina, california.

  25. featheredfrog says:

    “Sensors for the Evil Genius” has a number of radiation detection sensors. Most for indoor use, but certainly a starting point.

    Not as bad as SOME of that series…

  26. Mike says:

    bpw34 will not work. γ radiation is in the pico-meter wavelength range, the spec sheet suggests that bpw34 is good for 1100-430nm. That is an order of magnitude larger. It’s even useless for x-ray radiation with is in 10-0.01nm range.

  27. Beavis1975 says:

    @It’s kind of redundant:

    No one’s going to fall for that. There’s no way you can make a radiation detector without a microcontroller and some sort of digital readout! Your hoax was just too obvious this time… Next time, aim just beyond the edge of plausibility!

  28. pheo says:

    Radiation detection is no trivial matter.

    What kind of radiation we trying to detect?
    I’m guessing that there is the implicit assumption that only ionizing radiation is of interest from a health perspective.

    The Geiger Tube is really the most robust gamma ray detector.
    It’s basically a big gas scintillation cavity, but it requires high voltage (so it’s “too dangerous” for the kids)

    There should be some way to build a low-voltage/solid-state Geiger counter.
    Maybe a Zener Diode?

  29. Mrshko says:

    You’re problem is geiger detector costs. Sparkfun is too expensive, 80+ duckets. Look on ebay. Plethora of geiger tubes for cheap

  30. Bob says:

    This site shows how to build a geiger-muller-counting-tube and circuit to create a complete geiger-muller-counter. This site is full of tube projects. Looks like the author is some engineer of the old school.

    Google-translated:

    http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=n&tl=en&u=http%3A%2F%2Fwww.b-kainka.de%2Fbastel76.htm&act=url

    Original site in german:

    http://www.b-kainka.de/bastel76.htm

  31. Mike says:

    @pheo, zener diode you’re referring to seems to be the SiGe Pin diode. do you have a source for those in the correct wavelength range?

  32. SquantMuts says:

    @Mike

    I think photodiodes would not directly absorb the photons to convert into a photoelectric current. But you could measure the ionising path the ray/particle makes trough the junction, seeing a jump in the junction leakage current. That is what the maxim application note tries, and also shows the tradeoff you need to make of noise vs sensitivity.

  33. @Beavis1975 well… you could always wire up a mcdonalds free pedometer to show how many times your hands shook in a dosing.

    Maybe some neon lamps, some stickers, a PIC or two later and you’re ready to market it on newegg.

  34. I will say I have an unused circa 1969 victoreen civil defense geiger counter (bought cheap!) and it comes with a full wiring diagram so I’m sure its easily reproducible. Even the ‘detection chamber’ is really similar to the KFM.

    And of course here’s a whole page dedicated to the DIY digital crowd

    http://www.discovercircuits.com/G/geiger.htm

  35. daqq says:

    There’s a fair amount of homebrew Geiger counters out there the last time I checked. Using a Geiger tube, it’s pretty simple really – as Jeff noted. I believe I read somewhere some guy tried using a neon tube in a similar matter to a Geiger tube. Can’t remember where though.

    I’d stick with the Geiger counter concept as that is the only reasonably doable approach – scintillation counters require scintillators (a fair amount of materials can be used, even water will do, though don’t expect too good results) and expensive photomultipliers, or twice as exotic adn quite expensive and not half as sensitive special photodiodes – unless the radiation levels are extremely high, you get only VERY LOW light levels (as soon as the scintilation is visible to the naked eye, you’re not running fast enough).

    Then there are the more exotic ones, like HPGe and that sort of stuff – insanely expensive, big, cryocooled and for lab use only.

    And there are other smaller designs like http://www.amptek.com/oem.html which cost quad their weight in gold and mithril.

    So, the Geiger tube approach is the best and cheapest.

  36. zeropointmodule says:

    you could try and use a piece of x-ray intensifier film carefully placed downwards onto a ccd chip.

    a related hack is to use an NORP12 with the same intentifier in a light tight casing,as it is basically linear and predictable so easy to calibrate

  37. zeropointmodule says:

    a related hack is to use the bare CMOS sensor from an optical mouse, some of the older ones let you read the raw values from the registers on the chip.

    (thanks Sprite_tm!)

  38. Laurenceb says:

    Surely this fits the bill quite well

    http://www.techlib.com/science/ion.html

  39. alex says:

    I think this fits the bill as far as fallout goes http://en.wikipedia.org/wiki/Kearny_Fallout_Meter

  40. Urza9814 says:

    Am I the only one who saw that headline and wondered wtf a German reggae band was doing on hack-a-day?

  41. majolsurf says:

    There’s guy on twitter who is using his sparkfun geiger counter to send hourly tweets, based out of California. It’s mounted on his roof sending data via Xbee. While the news is reporting an increase is radiation levels his counts have not gone up.

    http://twitter.com/Geiger93933#

  42. hubert says:

    You can find those pen dosimeters used by medical personal or army cheap at surplus shops or sometimes on ebay, i have seen them for under 5$ each, maybe you could get hands on a batch of them for cheaper if you ask the right institution.
    here is another german page, the guy describes his long way to build a working geiger tube.

    http://www.fingers-welt.de/gallerie/eigen/elektro/geiger/geiger.htm

  43. jarrod says:

    Hack a photomultiplier tube from an old, old video camera?

    still requires a HV supply but these things are super sensitive to radiation, thousands of times more so than geiger counters. or at least the PM tubes designed for it are :P

    side note, I’m wishing I picked up the decatron pulse counter rmits physics department was chucking out a couple of years ago

  44. Jeff says:

    Here is a radiation detector I made In 20 min from a smoke detector and Arduino. took longer to make the video

  45. jimbob says:

    The easiest homemade detector would be an unpressurized ion chamber, you can make one with a tin can. I can’t comment on the associated circuitry as I have only seen a hand full of different schematics and they all seem to include pain in the ass power supply schemes. Calibration may be equally painful, I’ve never seen one that reads in counts per minute (CPM.)

    A system based on a Geiger Mueller tube would be the cheapest to purchase, easiest to design around, and simplest to calibrate.

    Price:
    < 100 USD

    Design:
    Start with an oscillator that feeds a regulated voltage multiplication network (diodes and caps), attach to GM anode, ground the cathode, couple the signal to a charge sensitive amp that triggers a multivibrator, and integrate for indication.

    Calibration:
    1———–
    Remove tube from circuit

    2———–
    Check Voltages. High volts will depend on particular tube, low volts depends on your silicon

    3———–
    Connect some sort of variable frequency input (preferably a pulse with similar width as the dead time of the GM tube you're using).

    4———–
    Cal to a particular CPM (CPM = Freq * 60) then check for linearity (if 1.66667 = 100 CPM then 3.33333 = 200 CPM, 33.33333 = 2000 CPM, 666.66667 = 40K CPM…)

    5———–
    Once you can determine that the linearity of your meter is reliable it needs to be checked with some reliable source ( a single known source should suffice.)

    6———–

    "scintillation counters require scintillators (a fair amount of materials can be used, even water will do, though don’t expect too good results) and expensive photomultipliers, or twice as exotic adn quite expensive and not half as sensitive special photodiodes – unless the radiation levels are extremely high, you get only VERY LOW light levels (as soon as the scintillation is visible to the naked eye, you’re not running fast enough)."

    – To compare a photo multiplier tube to a photodiode and declare the diode as the more sensitive or better suited for this particular application is silly at best. You either have no idea as to to how either of them function or you've experimented with both and failed to consider "basic rules of thumb", for one or the other. The PMT will always be able to see light that you cannot. Scintillation/PMT detection circuitry is, as far as I know, the best (most efficient and expensive)way to detect ionizing-radiation.

    "The Geiger Tube is really the most robust gamma ray detector.
    It’s basically a big gas scintillation cavity, but it requires high voltage (so it’s “too dangerous” for the kids"

    1st, I could be wrong, But I've never heard of a detector that can reliably detect ionizing radiation with a "low voltage".

    2nd a geiger mueller tube is not a "big gas scintillation cavity", it's not a scintillator at all.

  46. jimbob says:

    “There should be some way to build a low-voltage/solid-state Geiger counter.
    Maybe a Zener Diode?”

    No there is not.

    “No one’s going to fall for that. There’s no way you can make a radiation detector without a microcontroller and some sort of digital readout! Your hoax was just too obvious this time… Next time, aim just beyond the edge of plausibility!”

    Rest assured your arduino will handle the “plausibility clause?”

  47. macona says:

    I dont know what the point of this would be, I could see doing it for fun. IF something happens you will know. Most people wouldnt know what to do with the reading of a geiger counter. This is not like fallout 3 where you run away when it starts clicking and shoot up some rad-x.

    Anyway, for a small power supply to drive a GM tube an inverter for a cold cathode lamp. There is info and schematics on buiding a geiger counter around one here:

    http://www.coultersmithing.com/forums/viewtopic.php?f=7&t=244

    That forum is a good site in general if you are interested in nuclear and other fun stuff.

    http://www.coultersmithing.com/forums/index.php

  48. Doug says:

    Not that I’m saying not to try to help, nor that the DIY/hacking community is incapable helping, but the phrase a day late a dollar short comes to mind. I take it the product is to be used by people making decisions concerning their well being. Even a simple not safe/safe instrument needs to be accurately calibrated. How that calibration will be done is a major part of such a project. Given the implied urgency the best they can hope for is to find a project that meets all the needs, that doesn’t use obsolete components.

  49. Cameron says:

    @majolsurf There is no way that a geiger counter will show any signs of increased radiation level that isn’t just from normal fluctuations in background(background radiation increases after it rains). Students and professors at UC Berkeley’s Nuclear Engineering department myself included are measuring radiation levels in the air and rainwater in 12 hour intervals with state of the art radiation detectors. Updates are posted here:

    http://www.nuc.berkeley.edu/UCBAirSampling

  50. WestfW says:

    This is fundamentally a lot more difficult than it sounds, especially if you’re trying to give an indication of “health risk” rather than just radioactivity. For example, tritium is much more radioactive than plutonium, but I’d rather be exposed to the former!

    (All rather complicated by the lack of information in the press about just what sort of radioactive products are being released by the Japanese reactors. Sigh.)

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