[ RadSafe ] Cerenkov and Ra-228

[Franz Schönhofer]

Khalid,
 I am more than sceptical about measuring Ra-228 by Cherenkov radiation.
Ra-228 seems to have rather low-energetic beta particles, which might not or
only with a very low efficiency produce Cherenkov radiation.
 Probably you refer to the short-lived (6.13h) daughter Ac-228, which has
high energetic beta emissions. You would have to separate it chemically. It
would make much more sense to measure it by normal liquid scintillation
spectrometry than Cherenkov counting because of higher efficiency. Even more
sense it would make to follow our procedure for very fast, simple and
simultaneous determination of Ra-226, Ra-228 and Pb-210. I will present a
paper at the LSC conference in two weeks. It is a pity that you will not
participate, because there will be many more papers on radioactivity of
drinking water.
 BTW I know one paper on the measurement of Ac-228 by Cherenkov counting
from the working group of Schuettelkopf (and as far as I remember Godoy was
involved) from Karlsruhe. It is sure more than 15 years old and investigated
the use of certain chemical compounds to shift the wavelength of the
Cherenkov light emitted to enhance efficiency.
 Finally I want to point to a very common method for measurement of Ra-228,
namely either waiting after radium separation for equilibrium between Ra-228
and Ac-228 or to use the untreated water (dependend on the LLD you have to
achieve) and subject it to gamma-spectrometry.
 Hope this helps.
 Franz

 2005/9/19, khalid abdulaziz aleissa <kaleissa at kacst.edu.sa>:
>
> I am working on optimizing a technique for measuring Ra-228 (after
> proper Ra chemical separation) using Chernkove radiation. I wonder if
> any know any published work or interested researchers in this field.
> --
> KACST- King Abdulaziz City For Science and Technology.
> http://www.kacst.edu.sa
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