Jed, If he did a spectrum measurement for "a few minutes", he should have a decent sampling. This depends on the detector, of course, but all handhelds that I've dealt with (which is a limited sample) are designed for rapid detection/spectra collection. NaI isn't the best detector material, but it should be adequate. Usually the detector stores the last spectrum collected.
If he wants the spectrum he did get analyzed, I can get this done in several different ways. Chances are the "secret" may not be a gamma emitter at all, but it's worth a go. Is there any chance he a) still has the spectrum he did collect, and b) would be willing to share it? Debbie On Tue, Jan 18, 2011 at 1:57 PM, Jed Rothwell <jedrothw...@gmail.com> wrote: > [Francesco gave me permission to distribute this.] > > Dear Colleagues, > [...] > > * It was assembled also a twin gamma ray detector in order to detect e+e- > annihilation: this time almost no results. > Focardi was confident that they will get large amounts of such signal, as > in previous experiment. > This time the counts were close to background for coincidences and only > some uncorrelated signal were over background. > > * I bring a gamma detector, battery operated, 1.25" NaI(Tl). Energy > range=25keV-2000keV. > I measured some increase of counts near the reactor (about 50-100%) during > operation, in a erratic (unstable) way, in respect to background. > I decided to move the gamma detector from "counts" to "spectra" mode. After > few minutes Eng. Rossi realised that I was trying to identify something > "secret" inside the reactor: I was forced to stop the measurements. > > [...] > Francesco CELANI > >
