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Re: CDV-715 Use

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  • Geo
    1 ATM ( atmospheric pressure) Ion Chambers, even of excellent modern design reach their low end at about 3 mR/H full scale. This is with every conceivable
    Message 1 of 5 , Oct 1, 2006
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      1 ATM ( atmospheric pressure) Ion Chambers, even of excellent modern
      design reach their low end at about 3 mR/H full scale. This is with
      every conceivable improvement, far beyond my meager efforts. Their
      chief advantage is smooth response to a very wide range of energies,
      again something that is achieved only with superlative design and
      execution. A GM tube of any description and all sodium iodide
      scintillators have a big swing in their energy response, some of
      which can be corrected for at the expense of ultimate sensitivity (
      energy compensated GM tubes are wrapped in lead or cadmium).
      Basically the wrap cuts down the lower energies, making the overall
      response from the tube more linear.

      Energy response is the parameter that would make one isotope read
      say, 1 mR/H when another isotope of the same field strength would
      read 10 mR/H.

      Very sensitive ion-chambers are made with high pressure inside, as
      much as 10X atmosphere or about 150 pounds per square inch. These
      offer smooth energy response and extreme sensitivity down to the
      microR/H. Usually these are coupled with sophisticated computerized
      electronics, especially in the environmental monitoring mode.
      Handheld units are likewise very complex and needless to say
      expensive to the extreme. Earlier, much simpler versions would
      include the RADECTOR series, but their pressure is lower and
      sensitivity is of a lesser level too.

      None of these would be fodder for the home lab constructor in my
      opinion, as the shell material is of exotic nature, and 150 PSI lab
      gas is nothing to be played around with.

      Far safer are the gas flow proportional detectors. These are very
      sensitive and give an output that is proportional to the number of
      radiation events, making them ideal for true quantification studies.
      Their design is simplicity itself, and many examples can be purchased
      for peanuts on ePay. Electronics are slightly more advanced than the
      ordinary handheld, but again many units by Ludlum especially are
      already rated to run these detectors. The only reason they are not
      much more universally used is the fact that they take a special gas
      called P10, 10% methane, 90 percent Argon- not to mention special
      regulators and gas flow monitors. Nonetheless, commercial systems are
      available and can sometimes be had used at Home lab prices. I have
      managed to put together a complete gas flow system, comprising of
      Matheson regulator, Ludlum gas flow monitors, hoses with QC fittings,
      and an array of different detectors.....all at modest cost but over a
      long period of time. No gas has been purchased yet so I can't report
      on results, but this is a definite upcoming event - funds and time
      allowing.

      So many projects, so little time.................and far less $$$$$

      Geo

      --- In CDV700CLUB@yahoogroups.com, "Jim RabidWolf" <unclerabid@...>
      wrote:
      >
      > On the other hand, as you well know, a slight modification an make
      it actually useful (for betas) - if one took the time to add a
      seconde electrometer tube as a preamp, it can be pushed even further -
      the limitations of an Ion Chamber as only those of the designer's
      will and imagination.
      >
      > It's a waste of a possible good machine, really - but on the other
      hand with morons on e-bay pimping them as "geiger counters," the
      water's just a little muddied.
      >
      > I'm looking for a few cheep 715's (good meters, not destroyed) for
      just such a project. I refuse to pay $29.95 for a machine, purchase
      in a pallet load at $1.00 each. But I'll buy that pallet at cost....
      >
      > Jim RabidWolf
      > Uncle Rabid ( http://www.unclerabid.com )
      > We Repair Electronic Speed Controllers
      > For Asian Mini Lathes and Mini Mills
      > "Just Crazy Enough To Get the Job Done"
      >
      >
      > ----- Original Message -----
      > From: Geo
      > To: CDV700CLUB@yahoogroups.com
      > Sent: Saturday, September 30, 2006 10:00 PM
      > Subject: [CDV700CLUB] Re: CDV-715 Use
      >
      >
      > Anyhow, we already determined the CDV 715 can double as a wheel
      chock
      > and/or a single beer can cooler.
      >
      > Geo
      >
      > --- In CDV700CLUB@yahoogroups.com, Chris Smolinski <csmolinski@>
      > wrote:
      > >
      > > Finally! A use for a CDV-715! (other than as a doorstop)
      > >
      > > http://junkfunnel.com/sld/
      > >
      > > --
      > >
      > > ---
      > > Chris Smolinski
      > > Black Cat Systems
      > > http://www.blackcatsystems.com
      > >
      >
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