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Don't Cross the LHC Stream! (Maybe)
jamie points out this piece from always-entertaining Bad Astronomer Phil Plait, who asks this week the simple question "What happens if you put your hand in the beam of the Large Hadron Collider?" The thrill of discovery to me doesn't sound worth the worst-case scenario.
You get a built-in tool that makes it easier to masturbate.
They'd just stick a pig foot in there.
"So it was in 1978 that when the proton beam entered Anatoli Bugorski's skull it measured about 200,000 rads, and when it exited, having collided with the inside of his head, it weighed in at about 300,000 rads. Bugorski, a 36-year-old researcher at the Institute for High Energy Physics in Protvino, was checking a piece of accelerator equipment that had malfunctioned - as had, apparently, the several safety mechanisms. Leaning over the piece of equipment, Bugorski stuck his head in the space through which the beam passes on its way from one part of the accelerator tube to the next and saw a flash brighter than a thousand suns. He felt no pain.
http://www.wired.com/wired/archive/5.12/science.html
This is a man who looked into a proton beam accelerator that he thought was non-operational. It's already happened once before.
An artist makes unusual "sculptures" by putting acrylic blocks into the beam path of a relatively small electron accelerator:
http://www.dailymail.co.uk/sciencetech/article-1232908/Captured-lightning-The-artist-traps-fossilised-bolts-electricity-inside-acrylic-blocks.html
I don't know of any red lasers that have IR components. Lasers are, by definition, monochromatic. That's the idea after all. The reason some have IR as well is they are DPSS. They produce IR radiation directly, a frequency doubler then takes it up to the visual range. That's a lossy process, so the IR is much higher than the final output, hence an IR filter is needed. Green lasers work this way, at least all the ones I've seen. However red laser pointers are all direct drive, the diode outputs the frequency you want. That's why they are used for CDs and so on, keeps the cost down.
That is also the big deal with Blu-ray lasers (actually quite violet, not blue). Again, direct diode lasers. Means they cost less, use less space and so on, and of course being violet have a higher wavelength.
I've never heard of a red DPSS laser pointer.
Moral of the story - avoid high energy beams regardless of the wavelength or the particle kind because you never know what will slip by even in a supposedly "safe" circumstances.
Incorrect. Moral of the story: Do not look into laser with remaining eye.
Now that I think about it, I'm pretty sure everything I just said is completely wrong.
I think this is the comment you're referring to:
12. Bethany Says:
September 21st, 2010 at 8:20 am
Alright, here's what I calculated:
The protons are high energy with lorentz factor of gamma=7500, kinetic energy is about K=7×10^6 eV. The paper cited below says that the stopping power of a proton going 10^6 eV is about 2.5×10^8 eV cm^2 g^-1. Using the density of muscular tissue rho=1g cm^3 and the thickness of my hand of 1 cm, the energy deposited is 2.5×10^8 eV. In other units its 1.07×10^-11 calories, 4.49×10^-11 Joules, and 1×10^-14 grams of TNT. If there are hundred billion protons per bunch in the beam (as the video said) then for every bunch you get 4.49 Joules or 0.001 grams of TNT of energy. (emphasis mine)
There are two beams, each of which contains 2808 bunches. Don't worry about the effect of multiple passes, though, since there won't be any tissue left in the beam's path by the time the first pass is over.
A more informative comment showed up later:
31. Xerxes Says:
September 21st, 2010 at 10:45 am
I think the hand-beam question is best answered by this document: http://lsag.web.cern.ch/lsag/BeamdumpInteraction.pdf
Granted, a carbon block isn't an exact model of the human hand, but it's probably close enough. The key points are:
1) "this energy deposit over 85 s is long enough to change the density of the target material. The density decreases at the inner part of the beam heated region because of the outgoing shock waves in the transverse direction. As an example, after the impact of 200 bunches with a size of = 0.2 mm, a maximum temperature of 7000K and a density decrease by a factor of 4 is expected." The results of heating your hand to 7000K and increasing its volume by a factor of 4 are probably best not imagined. Since a full beam is 2808 bunches instead of 200, you might want to scale that by a factor of 10 too.
2) But on the other hand (hehe): "The beam tunnels through the target and deposits the energy with a penetration depth of 10 m to 15 m" Since your hand is not 10m thick, you won't pick up the full effect. This paper goes into some detail of the spatial distribution of the energy dump: http://cdsweb.cern.ch/record/972357/files/lhc-project-report-930.pdf So at hand-thickness of 2ish cm, you'd only get maybe an eighth of the effects of #1, so your hand will only reach the more modest temperature of 1000K (times 10 for a full 2808 bunches?). The shockwave from the blast will extend several cm in the transverse direction; translation, the rest of your hand will be blown off by the middle of your hand exploding. Probably the part of the accelerator apparatus downstream of your hand picks up the rest of the energy. The rest of you probably wouldn't want to be standing next to it when it blows.
Cool pictures of the effects of a low-energy (450-GeV) beam on copper plates are in http://dx.doi.org/10.1109/PAC.2005.1590851
(I spent so much time looking up references, several other people made the same points. Oh well.)
Note particularly the fact that if one beam hit the solid graphite beam dump without being swept around during the pass, the surface would be at 7000 C, and would be well in the process of exploding, by the time the first 200 bunches had hit. Your hand, having a lower boiling point than graphite, would begin to remove itself from the path of the beam somewhat sooner, and would therefore probably absorb rather less energy. That may be small consolation, though, since it pretty much means that the splattered remnants of your hand wouldn't be as intensely radioactive as the carbon in the beam dump would be.
Bugrit! Millenium hand and shrimp!
Fermilab had a beam loss event in 2003 (beam came into contact with part of the ring). The beam drilled a 2.8 mm hole through a 5mm tungsten support. It also etched a groove 25 cm long and 1.5 mm deep into a stainless steel collimator (after passing through the tungsten). Apparently this took about 8.3 ms (over several turns of the beam) before the beam dissipated.
I'm guessing if you could insert your hand fast enough (not possible, even if there wasn't a vacuum tube) you would end up with a nice small hole drilled through your hand.
This is the report from the Fermi incident:
http://beamdocs.fnal.gov/DocDB/0011/001185/001/FN-751.pdf
A man comes home from his work at the deli, and tells his wife, "I have a strong desire to put my penis in the pickle slicer."
"That's sick!" replies his wife. "You need help."
"I don't see any reason it would be sick", retorts the man, "I think it would be fun!"
Two days later, his wife comes home from an errand, and her husbands car is in the driveway. "You're home early", she says.
"Yes, I put my penis in the pickle slicer!" he smiles.
"Oh my God!", gasps his wife, "What happened?"
"I got fired! So did she!"
Why, without your clothes, you're naked, Miss Dudley!