plastic, beta, impactor

[FRAMEP@ORAU.GOV]

Bon jour a tous les "radsafers":

1. One more address for plastic scintillators:
                    Nuclear Enterprises
                    Sighthill, Edinburgh
                    Scotland EG11 4BY

                   44 (0) 31 453 5560

They used to have offices in the U.S. but I believe these were     
closed down. I am not even sure if the above address in Scotland is
still good.

2. Regarding beta dose calculations (or any internal dosimetry
calculation). Robert Loesch already referred to VARSKIN and Kristin
Erickson referred to a table in Jack Shapiro's book (which only lists
a few nuclides). There is an alternative. You can call the Internal
Dosimetry Center at Oak Ridge Institute for Science and Energy.
Specifically you can call Mike Stabin (615) 576 3449 or James Stubbs
at 576 9619. These guys are experts in internal dosimetry (using MIRD
or ICRP methodologies) and work for free. Their money mostly comes
from the FDA and the NRC. Skin dosimetry is not their specialty but
they have the know how to do it.  Like I said, they work for free.

3. Let me add a couple of comments to what has already been said
about annular impactors. This is not based on personnal experience so
take it for what its worth. The working assumption is that the
man-made aerosols are larger than 1 micron AMAD and that the
naturally occuring aerosols (eg. radon daughters) are smaller. This
is almost always true but any Pu fumes generated by chemical
processes, if present, should be less than 1 micron and not collected
by the impactor.

A greased planchet is often used to collect the particulates above 1
micron. The grease can lead to absorption losses of the alphas which
would vary depending on how much grease is used. Some sort of filter
material (eg. glass fiber) might serve as a better and more
reproducible collection medium.

I've often wondered how to best determine the detector counting
efficiency since the collected material is not evenly distributed
across the planchet but instead is concentrated near the edge. Liquid
scint might be one way if a good standard can't be found.

Hope this is of interest;

Paul Frame