Re: Missing H-3

[Keith Welch <welch@jlab.org>]

Jo, I agree with Zach Clayton.  You're going to get a "collection efficiency" or carryover factor or whatever you want to call it.  Depending on what you're trying to do, you may not want this to happen.  If, for instance you're trying to assess the H-3 activity without interference from other nuclides, you'd like it if you could get an equal caryover.  I recommend repeating the process several times, carefully controlling factors such as the fraction of distillate that you're capturing, and derive a collection efficiency for your analysis.  I would expect better than the 75% you got on that sample.  Are you using a "closed" distillation rig?   If not, you may be diluting your condensate.

> We boiled about 20 ml of tritiated water and condensated the vapor of about
> 2 ml. It appears that the initial H-3 concentration prior to boiling, and
> the H-3 concentration in the condensated water from the tritiated water
> vapor are different. I am aware of that the boiling point of tritiated water
> is slightly different from the ordinary water. The initial H-3 activity in
> the water is 2400 dpm/ml and the condensated water activity is about 1800
> dpm/ml. The boiling stopped when we collected about 2 ml of  water sample.
>


--
Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@jlab.org
Ph: (757)269-7212
FAX:(757)269-5048


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