Check it out. A big 3" dia. bottle of -325 mesh aluminum (usually used for fireworks, by the way) was put behind two inches of water moderation and irradiated for some 10 minutes at some of the highest sustained neutron rates my fusor has yet produced (the needle was into the 50 mrem / hr range at times.) After irradiation, the aluminum powder bottle got counted for another ten minutes or so. I see a peak there at 1.78 MeV, just where the Al-28 decay gamma ray should be.
But getting good counts and a statistically meaningful measurement is a problem. I did not subtract background on this run, but rather plotted it on the same graph in blue for simple comparison because there are so few counts.
Nevertheless, you can see a bunch of counts in the 1.78 MeV peak that are absent in the background...and you can also see what I think is the K-40 peak popping up in both sets of data.
A big counter, like Richard's new 4-incher or even a 2-incher, would be far superior for these short-half-life, low cross-section activation experiments.
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2003-02-25 22:03 Aluminum Activation (barely!!) 
(Carl Willis) [Latest: 2003-02-26 16:38]