Carl G's fusor and team

[Doug Coulter]

http://www.youtube.com/watch?v=OWLhxYjMAtQ


This is Carl Greninger's fusor project and some kids he's recruited to help -- a good deed he's done there. They've obviously done an obsessively detailed job of work on this thing -- good show.
Me, I'd be concerned that if it actually made a lot of neutrons, the gammas from capture in the boron shield would be worse than the disease, but I see it's fairly safe that way for now, with a glass bell jar severely limiting the input they can run. Still, a nice job all around -- and a good deed to bring in more young folks and get them going with science.

[chrismb]

I think the amount of cadmium in the shield is far more dangerous than any neutrons!

[vmike]

That's good stuff! Carl does a reasonable job of conveying science to a journalist as well. Kudos to Carl, keep the faith brother. My only question, (warning! warped humor) and this because I'm tall. Why'd you put the controls down next to the floor!

mike

[Doug Coulter]

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.

[chrismb]

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).

See 3'00" to 3'30".

[Doug Coulter]

Thanks Chris. Hopefully they put the lead on the outside! Belt and suspenders, I suppose. I really kind of doubt they are at 400k/second with that rig, but...that's not their point anyway, so I'll accept that and the fact that even 400k/sec isn't "micro-watts" plural, it's a fraction of one if our other calx here are correct. Picking on that stuff would I think miss the point of the exercise.

At least it's a real fusor that obviously works. So much of what I run into on youtube clearly isn't, just a slapped together thing and some hope -- usually with a very inadequate vacuum system and very impure fuel if I've learned to read the pictures well enough. I'd guess a fraction of those attempts will be successful at some point. All too much depends on attention span and discipline, things that are often lacking in young/amateur efforts (just going by my own when I was lots younger). I'd guess that was A, if not THE, big contribution Carl made to his group's work.

You know, with all I've been learning lately about capture gammas -- one might just devise a pretty decent neutron detector off that phenomenon. Just take a bunch of moderator, put lead around it, and stick a scintillator (or anything else energy-proportional for gammas) in it and use that with a window discriminator. Might be decently sensitive and would be inexpensive. I'll put that idea on the list of things to try out. Even plain H gives 2.2 mev capture gammas, after all - and is pretty safe to handle as a plastic or wax. B10 gives 4.44 mev, Cd gives lower energies (depends on which isotope). It's pretty easy to load up wax with some boron compound (boric acid or borax). Might be helpful for many who can't get the exotic 3He or B10 going for whatever reason. Even a plastic scintillator has some energy resolution, probably plenty for that.

[Mark Bickley]

Wow he must have good knees or lay on the ground to work on it that's crazy.