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OT: Gamma Spectroscopy

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  • OT: Gamma Spectroscopy

    So, A couple weeks ago I found a Harshaw 2"x1.5" NaI(Tl) scintillator attached to a 6199 PMT at a surplus store for $3. Finally got a socket and made up the dynode string and it seems to work well. I am running it off an old Ultravolt power supply.

    I decided to give PRA a try, It is a free piece of software that plots voltage height vs occurrence into a histogram that will show you the gamma spectrum of a radioactive source. I ended using my desktop PC which can handle 192khz and 24bit input. I found the settings in the Sound control panel make a huge difference in the amount of noise. 100% volume and +20db amplification gave me virtually zero background noise shown in Intune and there was an audible difference when I monitored through speakers. Intune shows nice clear pulses. The first pic is a capture from my Tek TDS340A of the pulses coming out of the tube.

    I need to get a Cs-137 source ordered. Once I get that I can get the thing calibrated to show the electron energy the detector sees. I am really not sure if this thing is working right until I get the source. The problem with the U ore is all the daughters produced with the decay of the U.

    -Jerry


    IMG_2238 by macona, on Flickr


    Scintillator PMT output by macona, on Flickr


    Uore2.475 by macona, on Flickr

  • #2
    You find some of the coolest junk.

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    • #3
      Trying hard not to flaunt my ignorance, but what will you use it for? I have to agree, though, a neat find, and the price is right.Bob.F.

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      • #4
        Somebody bought something for 3 bucks. It's electrical. And Uranium is somehow involved.
        How am I doin'?

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        • #5
          Yeah, some of the daughters of U decay are real bitches, and all of them are a little heavy for my taste.
          Any products mentioned in my posts have been endorsed by their manufacturer.

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          • #6
            and a bitch to machine, even with flood suds
            Just got my head together
            now my body's falling apart

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            • #7
              You can use it to figure out what is in stuff. Like last year when fukushima went up I could have seen what isotopes were in the rain water.

              Wiki has a bunch on it:

              http://en.wikipedia.org/wiki/Gamma_spectroscopy

              It looks like something I am doing is wrong with my set up. Not sure if I have a bad photomultiplier tube or what.

              -Jerry

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              • #8
                The only reason you got that for $3 is there's only 2 people on earth that knows what it is, you & the guy that donated it & he probably died of gamma ray poisoning so it all you baby!
                "Let me recommend the best medicine in the
                world: a long journey, at a mild season, through a pleasant
                country, in easy stages."
                ~ James Madison

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                • #9
                  AND, after we find what is in the rain water, Then what do we/you do? I don't think I need one. Bob F.

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                  • #10
                    Been a while since I was involved in this stuff but I suspect that a Cs 137 source larger than a smoke detector will require a specific NRC license. Major pain in the ass and red tape.

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                    • #11
                      Nah, they are usually around $50 to $80 depending on amount.

                      http://www.spectrumtechniques.com/radioisotopes.htm

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