Re: isogenerator solution problrm

[jriley@lib.drury.edu (Jim Riley)]

We have used a Cesium/ barium 137 source for more than twenty years.  I
don't recall that it was purchased through pasco but is probably an
identical unit.  We are approaching one full half life (30 years) and the
source is still useful.  We use exactly the same eluant.  I have noticed
recently that the first flushing doesn't produce much activity.   About a
minute or so after the first flushing a second flushing yields a very active
solution.  Repeated, rapid flushings after that yield diminishing returns.   

> Some two years ago, we bought the Pasco Isogenerator Kit (Barium-137m),
> #SN-7995, for half-life experiments. It worked exellently, until the the
> original eluant solution run out. We made new solution according to the
> information in Pasco's catalog (0.04 N HCl 0.9% NaCl in distilled water),
> but can't get any activity out of the generator with it. The documentation
> says that pH of the solution should be 9. Now my chemistry is quite rusty,
> but one might think that just acid and neutral salt in water will not make
> pH higher than 7.
>
> Could anyone tell, how should one make a eluant solution that works? 
>
> The generator is used only about 20 times, not 100 which it should last at
> least. Pasco catalog also tells that the generator has "a shelf life of
> well over a year". Surely this can't mean that the generator will die in a
> couple of years, whether used or not?
>
> Ari.Hamalainen@Helsinki.FI
> Univ. of Helsinki, Department of Physics
> tel +358-9-1918311 (desk), +358-40-5143867 (mobile), fax +358-9-1918680
> http://www.helsinki.fi/~aohamala/
Jim Riley, Department of Physics
Drury College
900 N Benton Ave.
Springfield, MO 65802
e-mail: jriley@lib.drury.edu
Phone:  (407) 873 7233