The Big Bang Theory Wrong?

Originally posted by sonhouse
You are forgetting one unavoidable problem with that: the outgassing of material from whatever case you are holding the vacuum in. The walls of the container will outgass SOMETHING and will add to the problem of achieving your ultimate vacuum.

You can't get around that. The uncertainty principle takes care of that, since there will always be atoms that ...[text shortened]... n the escape energy of the surface no matter what material you use, even at zero degrees Kelvin.

But surely it must be possible to have a very small vacuum chamber with walls made of metal or even glass and have so few cracks and impurities in those walls (and cool it to below 1K if you like ) so that the number of molecules outgassing from those walls per second per meter squared would be so low that there is at least a none-zero chance that there could be, say, a whole hour period during which not a single gas molecule outgassed from its walls and thus you could have a total vacuum for, say, an hour?

Originally posted by humy
But surely it must be possible to have a very small vacuum chamber with walls made of metal or even glass and have so few cracks and impurities in those walls (and cool it to below 1K if you like ) so that the number of molecules outgassing from those walls per second per meter squared would be so low that there is at least a none-zero chance that there could b ...[text shortened]... gas molecule outgassed from its walls and thus you could have a total vacuum for, say, an hour?

Nope, the vacuum at Cern is as good as we can get it, the less free flying molecules the better for the quality of the beam being shot down the middle. A molecule that collides with the beam means there is one molecule or atom of the beam that gets neutralized and therefore no longer subject to the rules of electromagnetism like the steering electrodes and acceleration elements and so forth so you want as good a vacuum in there as possible. They use all kinds of technologies to get where they are now, like titanium sublimation pumps, cryo pumps, ionizing radiation like UV and so forth and still after all is said and done the vacuum is still a thousand times worse than the surface of the moon.

Believe me, they would be as happy as a pig in poop if they could get vacuum even as good as the moon but they are far from that.

My ion implanters use the collision effect to self focus but they would not want that at Cern. My machine only accelerates ions to at most a few MEV, and mostly 0.2 MEV. For semiconductor manufacturing you don't need more than an MEV or so, it relates to how deep you want the dopant to penetrate the substrate, the higher the accel voltage the deeper the penetration. In fact the more dense the semiconductors get as time goes by, the depth of the devices goes down along with the height and width and that means lower and lower accel voltages needed, and our implanters have a voltage bucking mode (the source of the ions has to be accelerated to something around 50 KEV for efficient ion extraction) so if you want say, a 5 KEV implant (shallow depth) then you have to buck the extraction potential with the opposite polarity at 45 KEV in this case which means the acceleration voltage goes in reverse and actually slows down the velocity of the ion beam coming out of the source so you end up with your desired 5 KEV implant.

Originally posted by sonhouse
Nope, the vacuum at Cern is as good as we can get it, the less free flying molecules the better for the quality of the beam being shot down the middle. A molecule that collides with the beam means there is one molecule or atom of the beam that gets neutralized and therefore no longer subject to the rules of electromagnetism like the steering electrodes and ...[text shortened]... velocity of the ion beam coming out of the source so you end up with your desired 5 KEV implant.

Well, I learn something new every day 🙂
Perhaps they should move Cern to the moon to get access to the better vacuum? the vacuum tunnels may have to be a bit deeper underground there though because there is no atmosphere there to shield against radiation and high-speed ions so you would want extra depth of rock to be between the vacuum tunnels and the surface.

Originally posted by humy
Well, I learn something new every day 🙂
Perhaps they should move Cern to the moon to get access to the better vacuum?

I had thought about that from my work on ion implanters, we get vacuum sometimes into the 8 range (10 ^-8 torr) but I think the moon is something like 10 orders of magnitude better so I was visualizing what an ion implanter would look like on the moon and it would be incredibly simple there. Certainly no vacuum pumps or big frame needed (3/4 inch thick special stainless steel, non magnetic because of the very strong magnetic fields used for various reasons I won't take up your time going into here) and such, so the only thing we need would be to support the ion source mechanism and keep everything in line for the beam transport. We use N2 injection into the beam sometimes for self focus effects, that would probably not be used on the moon but the whole machine would be an open air looking contraption. You have a beam scanning section that involves several different types of techniques but all of which could be used, like electric field beam steering, magnetic beam steering, mechanical movement of the substrate (the thing being implanted) and so forth and an ion counting system that tells how many ions you have implanted the substrate with, whatever the dopant is, like Arsenic, phosphorous or boron, the big three of most semiconductor uses but there are other dopant elements to use.

I wonder how long the various parts of the machine would need to stand out in the bare lunar surface, how long it would take for the parts to outgas and get to something like the background vacuum level of the moon in the immediate vicinity of the machine? I'm sure if you had an ion gauge tube or some such, it would show a big deterioration in the quality of the vacuum as available on the surface of the moon till all the outgassing was finished, that might take a week or two.