Re: shielding for 86-Rb

["baumbaug@nosc.mil" <baumbaug@nosc.mil>]

        Rhonda,

        From my personal past experience, this is one of the times that you
need both types of shielding.  Rb-86 has some "big boy" betas (one almost 2
MeV) that could produce some pretty hefty bremstrahlung x-rays using Pb
alone, AND some big boy gamma photons (1.8 MeV) as well.  In addition there
are a lot of cascading x-rays produced internally, so its pretty messy to
work with (exposure-wise)unless you use due caution.

        Put the plexiglas between your source and the lead - and your
researcher.  This will help shield against the betas and you won't be
producing as many nor as strong (MeV wise) x-rays.  Most of those produced
will (hopefully) be attenuated by the Pb.  I think that you'll need more
than "just" lead sheets that are so popular now-a-days (usually 0.030"
thick).  For 1 mCi you may need a couple-three of thickness' of Pb sheets or
Pb bricks.  

        P.S. Remember to have your researcher shield the rest of the lab
from his experiment, not only himself!!

        P.P.S.  Like P-32, Rb-86 tends to migrate around the lab area by
"sticking" to everything (especially rubber and some plastics), however,
like P-32, using a survey meter it is "easily" detected.


        Hope this helps,

        Joel  Baumbaugh



        Std. Disclaimer.  The opinion above are (not necessarily) those of
my employer, but are mine alone.




At 12:12 PM 11/12/96 -0600, you wrote:
>    I am not a health physicist, and so am seeking the help of those on this
>list who may have experience working with isotopes that are both beta and gamma
>emitters.  I would like to know what sort of shielding is appropriate for
>someone working with around 1mCi of 86-Rb in a research lab situation.  
>    The advice I have been giving is to treat it like a pure beta emitter and
>use plexiglass for primary shielding, since most of the emissions are betas. 
>However, the user plans to treat it like a gamma emitter and use lead (i.e.
lead
>shielding around the source, wearing a lead apron).  Is the best solution
to use
>plexiglass as a primary shield with lead as a secondary shield?  Any help will
>be appreciated!
>
>Rhonda O'Keefe
>rhonda_okeefe@cambneuro.com
>
>
>
Joel T. Baumbaugh (baumbaug@nosc.mil)
Naval Research and Development (NRaD)
San Diego, CA., U.S.A.