Could he have put the controls low to train them for a life on their knees? As an old computer guy I recall spending a lot of time "in the position" doing "plumbing" on boxes, and sometimes remarked "For this I studied? I could have become a plumber and made better money! (and gotten more tolerance for arrogance)". I hesitate to suggest what the motivation might have been re the female participants
. (Bad Doug, down boy!)
Now I'll have to watch it again, last time was when he first posted this on fusor.net and I thought he said he used boron in the wax "shield". But either that or Cd will make capture gammas that are hotter than what comes out of the fusor (as will capture in hydrogen). It looks well enough contained to limit any risk of ingestion. That part is probably mostly for show and to instill good habits in the students - someday they might have to work on something REALLY hot, after all -- let's hope they are that successful.
In re that - I once had an NaI head near my fusor and saw some real hot gammas, but it wasn't a super good one or on an MCA, so I can't say just exactly what the energies were. In light of what I understand now, I'll have to do that again with a good one on an MCA and see if we can see the lines from N capture in H, or whatever else is around there. It
was near the 3He moderator at the time and that might have explained it. The thing is, both the I and the Tl do activate near a bunch of neutrons, and you'd really like to not ruin a good gamma spec head for several half lives of those. That will have to be a real short test! Should be OK as I had a monstrous count rate.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.