Radiation detector, help needed!

We got inquires from Shigeru in Tokyo about Geiger Mueller Tube, as the nuclear accident in FUKUSHIMA is escalating.

Can open hardware community do something to help in this? Seeed Studio is now sourcing sensors, then assemble quick measurement tools,  ship as many/fast as possible to Japan.

Since we have no previous experience with such device,  your help is needed!

If you have experience in making such device, some quick questions:

1. What would be the right sensor for such detection? Will the education purpose GM tube work?

2. Any recommended peripheral circuits?

3. Does such Geiger counter needs special calibration? Or can we calibrate it with commercial device?

All creations will be open source and donated, thank you for helping out!

109 thoughts on “Radiation detector, help needed!

  1. It’s getting pretty hard to find lantern mantles which contain Thorium. Due to public aversion to anything radioactive, manufacturers now use a different formula.

    Both lantern mantles and smoke detectors emit alpha radiation (and a little gamma, but mostly alpha).

    Some GM tubes will not register alpha, simply because the window is too thick. Alpha is blocked by just about anything, including a couple of inches of air.

    This means that to measure alpha you need a sample that’s right up against the GM tube window, otherwise it’s blocked by the air.

    Because of this, measuring alpha isn’t very useful for the Japanese folks – the radiation of concern over there is beta and gamma.

    It’s a good idea though. I recently found this link which shows how to measure alpha using an uncapped power transistor:

    This will measure alpha. Add an old smoke detector and you have an interesting experiment – if you can eliminate the electrical noise.

  2. I guess we haven’t been able to link up via E-mail.

    I think there may be a problem in your schematic. A CCFL inverter usually puts out a lot of current – 10ma if memory serves. There is no current limiting resistor between the rectifier and the zener diodes. The diodes will
    be bearing the entire current for all voltage over the zener voltage.

    Your zeners add to 450 volts. Suppose the CCFL puts out 500 volts at 10ma. That means that the zeners have to shunt 50 volts at 100ma, which is a whopping 0.5 watts. The zeners are probably rated much lower than that – they will heat up and burn out very quickly.

    You should limit the current going into the zeners. A 1 meg resistor between the zeners and the rectifier would limit the current to 0.45ma, and 50 volts at 0.45ma is .022 watts, which is much more reasonable for zeners to handle.

    The GM tube needs very little current – 0.45ma is plenty.

  3. @ Okian Warrior

    Thank you very much for your mentioning of Fast Recovery Diodes. Not only did this help my circuit but it helped me troubleshoot a problem.

    Thanks again.

  4. I sent an E-mail to the address listed above and have received no response.

    Your turn. Try contacting me here:

    Barrabas (at) Barrabas (dot) MV (dot) com

  5. I sent you two emails and I’ve got no answer. Is the email correct?
    I am interested to invest in this factory.
    =============
    #1 written by AgentG
    about 2 days ago

    Please feel free to email me directly to
    goel (dot) tx (at) gmail (dot) com

    flo:

    So, how can we contact you?…
    VA:F [1.9.6_1107]Rating: 0 (from 0 votes)

  6. Looking over your schematic, I suspect that there is a problem.

    I’d like to start a dialog with the designer. Please contact me from my website, or send a note to the registration E-mail for this blog.

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