*"If I want a small piece of beryllium that will fit in the well of an Am-241 source, to get maximum neutron flux, I might arrange to buy some pieces like that."* This is wrong thinking. To get the most neutron intensity, a very thick piece of beryllium (Be) is required to increase the probability of alpha particle interaction with a Be atom.
A very thin piece of Be will not convert all the alphas to neutrons. After the neutron is produced, it will not be absorbed by Be atoms so a thick berillium tagret will not affect the neutron. Cheers: axil On Sat, Dec 8, 2012 at 5:28 PM, Abd ul-Rahman Lomax <a...@lomaxdesign.com>wrote: > At 01:51 AM 12/8/2012, Eric Walker wrote: > >> On Fri, Dec 7, 2012 at 10:47 PM, Abd ul-Rahman Lomax <<mailto: >> a...@lomaxdesign.com>a**b...@lomaxdesign.com <a...@lomaxdesign.com>> wrote: >> >> Would it cut cleanly, if thin enough, or would it crush? There could be a >> way to pull this off safely, with capture and proper disposal of any dust. >> Do it under water? Waste disposal? So ... maybe. But that's not for now. >> >> >> The problem is that you don't find out if it what you did was safe for >> five years, and then you have a 1/3 chance of dying or being disabled. >> > > The danger of beryllium is real and subtle. However, it's also being > exaggerated here. If one is exposed to serious levels of airborn beryllium, > which are pretty small, yes, even a subacute exposure have no symptoms for > many years (sometimes 20) and can pop up years later as very serious > chronic disease. But the experience with beryllium was with workers at > beryllium plants who were exposed to the material, at substantial levels, > day after day, for years, and if those people contracted berylliosis, > *then* there was a one-third chance of a seriously harmful outcome, like up > to and including death. > > If I were to take a piece of thin beryllium foil and cut it with some > snips, once or a few times, the chance of serious beryllium exposure is > extremely small. And even that "bold move" I'm not going to engage in > without a lot more research, and possible some serious precautions. I'm > going to experiment first with my solid piece of beryllium, which is very > safe. As long as I don't heat it seriously, or do any of a number of other > unwise things. > > I have children. I have utterly no willingness to risk their health. If I > were to do anything more bold than allowing this piece of beryllium to sit > on top of an Am-241 smoke detector source, I would not do it here. And I > might easily not do it at all. If I want a small piece of beryllium that > will fit in the well of an Am-241 source, to get maximum neutron flux, I > might arrange to buy some pieces like that. There are places selling > machined beryllium. And I'd attempt to recover my cost by selling the > pieces for exactly that application. > > The children will not be allowed to handle the beryllium. They will know > about it, though, and they will know that it is dangerous. Even though it > appears that one can swallow pieces of beryllium metal without harm, we > will not run that experiment. > > Here is what I will say to anyone considering using beryllium. It's a > totally cool substance, in many ways. However, anyone who is going to > handle it should study the MSDS guidance, and take it very seriously. Many > people have died from contact with beryllium. Airborn, it is totally nasty. > > There can be a bit of hysteria around it, see http://www.f1fanatic.co.uk/* > *2007/02/08/banned-beryllium/<http://www.f1fanatic.co.uk/2007/02/08/banned-beryllium/> > > It's a judgment call. Beryllium has been used for jet aircraft brakes. > That generates dust. I can see why people would get upset. Bad News for Air > Force Mechanics. Beryllium for an engine piston, as described in the > f1fanatic site probably does not emit serious beryllium in engine exhaust, > or else the piston would wear out quickly. But that could be addressed by > testing. > > I'm looking forward to handling the metal, it is reputed to be amazingly > light, very palpably so. Source after source said that beryllium metal > parts were not a problem, even while warning very seriously about dust > (metal, oxide, or salts of beryllium). Absorption through the skin does not > appear to be a problem, doesn't seem to happen. They say that if a piece of > beryllium is lodged beneath the skin, remove it... that does seem like a > good idea, eh? >
