currency strips "salted" for neutron activation analysis?

Re. detectability of the funny plastic threads in recent U.S. currency issues: I think it would be interesting to try neutron activation analysis on currency. To do this, you would bombard the currency with neutrons and then look at the activated gamma spectrum to see how much of what odd trace materials might be present. I don't have any specific knowledge that the threads are "salted" for easy identification but this technique would work very nicely and has been used elsewhere. I used to have ready access to a californium source but don't any longer. Anybody else out there want to give this a try? Brad D.