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gamma ray detection

Discussion in 'Electronic Design' started by Jamie Morken, Aug 30, 2010.

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  1. Jamie Morken

    Jamie Morken Guest

    Hi all,

    Is there a semiconductor replacement for the traditional geiger
    avalanche tube with similar performance? Or what are the best types of
    semiconductors to use for this? Ideally a 2dimensional array like a CCD
    or CMOS camera, but a geiger camera is what I am thinking of. The
    application is for measuring emissions from weak gamma sources to see if
    single event emissions have a measureable beam angle.

    cheers,
    Jamie
     
  2. Bret Cannon

    Bret Cannon Guest

    Silicon drift detectors are used to detect x-rays (see Amptek for example),
    but due to the low atomic number they have poor sensitivity for higher
    energy gamma rays.

    High purity germanium detectors at liquid nitrogen temperatures have
    excellent energy resolution, but can easily cost more than $100k each.
    Mercury zinc telluride crystals are used for gamma detection, but need
    pixelated electrodes for the best performance as well as sophisticated
    electronics to deal with the high density of p-type traps and are also
    expensive.

    If you only want to detect gammas and not measure their energy, you might
    want to look a plastic scintillators or perhaps thallium doped cesium iodide
    crystals as less expensive alternatives to semiconductors.

    Bret Cannon
     
  3. : > Is there a semiconductor replacement for the traditional geiger
    : > avalanche tube with similar performance?

    : If you want similar performance to a geiger tube, why not
    : a geiger tube? It'd be difficult to match the active volume

    The 'multipixel' version of the Geiger counter is known as the
    Wire Chamber.

    Regards,
    Mikko
     
  4. Tim Williams

    Tim Williams Guest

    DOSBox.
     
  5. Jamie Morken

    Jamie Morken Guest

    Hi John,

    That is very cool, 400 pixels with a single wire! :) I guess the mylar
    sheets are charged like a HV capacitor, and the wire is not charged but
    has a constant current source put through it from the measurement
    circuit, and somehow the modulations on the current can tell you
    accurately what part of the wire had an electron/charged particle fly by
    it? I guess it is like a network analyzer or something hooked up to the
    wire. How does the sensitivity to gamma rays compare to a typical off
    the shelf geiger counter? Also do you use electrical insulation between
    adjacent columns and rows to prevent detection cross-talk? Sorry for
    all the questions but it is an interesting device. :)

    I think one limitation though may be detecting nearly spaced or
    simultaneous events, since there is only one wire, if there are multiple
    electrons/charged particles flying by in different locations I'm not
    sure if that could be detected with one wire?

    cheers,
    Jamie
     
  6. Jamie Morken

    Jamie Morken Guest

    Hi,

    That X-Y wire chamber sounds very cool. I wonder if anyone ever tried
    hooking it up to a strong gamma source instead of a particle source?
    The experiment I was interested in was to see if a single gamma ray can
    be detected by multiple "chambers" at the same time. It sounds like the
    setup's you've worked with are capable of finding that out. Ie. one
    experiement could be to record the X-Y grid distances between
    simultaneous detections as they occur over time, and then average them
    to see if the average distance is less than the distance that would be
    expected if these simultaneous detections were from separate gamma rays.
    If the distance is less then I think it could be assumed that a single
    gamma ray was being absorbed twice.

    cheers,
    Jamie
     
  7. Martin Brown

    Martin Brown Guest

    Printscreen and paste the buffer into your favourite graphics app.

    Regards,
    Martin Brown
     
  8. JW

    JW Guest

    That seems to work fine for a DOS *window*, but a when running a full
    screen DOS session CTRL + ENTER from the DOS command line, it does not
    work. At least on my machine it doesn't, I get only whatever was on the
    screen in Windows.
     
  9. JW

    JW Guest

    Correction ALT + ENTER.
     
  10. Martin Brown

    Martin Brown Guest

    Try running it as a Windowed DOS program and use Alt-PrtScrn when you
    want to do screen capture. Otherwise I suspect you will need to install
    some antique TSR with a Windowsian twist to make full screen DOS mode
    PrintScreen capture behave like a normal Windows application. Blame
    MickeySoft!

    There is a possibility that PrintScreen is working, but that PowerBasic
    is bypassing the screen buffer it is supposed to use.

    Regards,
    Martin Brown
     
  11. Tim Williams

    Tim Williams Guest

    ....Or install DOSBox...

    Runs better anyway (semantically speaking, but always slower), since it's
    fully 32 or 64 bit. Can't run NTVDM in 64 bit mode.

    Tim
     
  12. Sjouke Burry

    Sjouke Burry Guest

    I tried two dos-age grabbers, they did text oke, but graphics was
    hopeless, with confused multiple copy's in the gif file.
    If you(OP or others) want them, let me know.
     
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