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58 mins ago The Large Hadron Collider Was Activated To Much Whoopee Answered

LHC activate! So far I'm still alive and it appears that that our universe will not be ending. This comes much to the dismay of false prophets everywhere. Though as gmjhowe points out [http://Gizmodo http://gizmodo.com/5047732/large-hadron-collider-why-you-really-wont-die-today] indicates that our time of death may have been miscalculated. Although the beam is active, the collision wont happen till October.

We've been bringing you the lowdown on the LHC for a while now. You know there has been some concern that this would be the [https://www.instructables.com/community/Its-the-End-of-the-World-As-We-Know-It-.../ end of the world] due to the creation of black holes. And now the The Large Hadron Collider is activated and ready for collisions. And those crafty CERN scientists have captured our attention like a presidential scandal.



I get to go on a trip to CERN to the LHC as part of my Physics course, it'll be sweet. Also, the UK's contribution to this is less than peanuts. Seriously. Each year the UK spends £120m on peanuts, while we only contributed £80m to the LHC :-P

You are too lucky, I wonder how much you will actually get to see in person. Very jealous!


9 years ago

that black hole stuff is just cr*p, the actual energy thats getting released there is about the same as two wasps bumping into each other, this is because altho the particles are going fast, they weigh almost nothing, which means that IF a black hole would be created it would be a very small and slow one, AND these type of collisions happen all the time, the sun shoots particles at high speed towards earth, an the moon, and just about every other planet, so do all other stars, and there aren't black holes popping up all the time, are they?

If there is terminology I use below that is unfamilar to you, I would strongly encourage you to type it into a Wikipedia search. The physics articles in general are reasonably well done and accurate.

  • "the actual energy thats getting released there is about the same as two wasps bumping into each other"

The energy scale you should be interested is not macroscopic ("wasps"), but rather the masses of the particles involved, both what we're colliding (1 GeV mass protons with energies of 7 TeV each) and what is produced in that collision. With a total collision energy of 14 TeV you can produce a neutral particle with mass right up to that 14 TeV limit, or a pair of charged particles (particle-antiparticle pair) with masses up to 7 TeV each.

  • "altho the particles are going fast, they weigh almost nothing, which means that IF a black hole would be created it would be a very small and slow one"

Yes, that's exactly the point! "Black holes" are geometric distortions of spacetime. Those distortions can happen on any length/mass scale. Astrophysically, the processes that create black holes involve stellar and galactic masses, so that's what we see. It is certainly possible (and some theoretical models predict) that the energy density in LHC collisions could be high enough to allow production of black holes at the TeV mass scale. That means, trivially, that the BH will be "very small and slow."

  • "these type of collisions happen all the time, the sun shoots particles at high speed towards earth, an the moon, and just about every other planet, so do all other stars, ..."

In fact, very high energy cosmic rays incident on the atmosphere do undergo collisions with the same or higher center-of-mass energies as the LHC. This has been pointed out in numerous papers as a way of investigating various exotic physics models prior to (or instead of :-) using LHC collisions.

  • "... and there aren't black holes popping up all the time, are they?"

We don't know that. What we "know" (since we're still around :-) is that stable, accreting BHs aren't popping up in the atmosphere or body of the planet.

The problem is that standard model black holes aren't permanently stable.
Hawking radiation --- the production of e+/e- pairs from the stored gravitational energy at the event horizon --- has a rate ("black hole evaporation") which scales inversely with the BH mass. Astrophysical BH's have evaporation rates as long as the lifetime of the Universe. The small, TeV scale BH's hypothesized for the LHC (or from UHECR interactions) would evaporate in 10-20 seconds or so, about the same as the lifetime of the "regular" particles we will be studying there.

In other words, even if (when) we produce a BH, it won't stick around long enough to interact with the detector, let along interacting with the planet. This also makes it complicated to recognize, in the data recorded by the detector, that you actually made a BH in some particular collision.

The simplest idea we've come up with is to look for events where the particle distribution is "thermal", rather than having the angular and energy distributions typical of a cascade of "regular" decays. How this is actually implemented in practice, and how you do the background rejection, is part of the active research by LHC physicists.

For comparisons... 14 Tev is about 2.25 microJoules. The capacitor in a disposable camera flash attachment has about 5 Joules of energy; two MILLION times more. So the energy involved is quite small, in an absolute sense. Of course, it's a HUGE energy to be put on a single elementary particle. The 5J in that flash capacitor is distributed across something like 2*1017 electrons (if I did my math right...)

Exactly so (and it looks like you got the math right; the flash cap puts out 10 mA?). The key is the energy density, not the absolute value.

300V, 100uF, so Q= 0.03 columbs. Multiply by magic number to get number of electrons... (4.5J rather than 5, though.)

Sorry I didn't reply sooner; thanks for the correction! For other readers, the magic number is 1.6 x 10-19 coulombs/electron = 6.25 x 1018 electrons/C.

expensive shiny goodness not go boom? Yay! (we payed millions for that? and no black hole? what a rip off!)

It sorta broke, long before they got to the possibly-black-hole-producing experiments. Broke in a way that will apparently take several MONTHS to fix (involves warming up things to room temperature, fixing them, and then cooling them down again, IIUC. Since you're talking superconductors kept at near absolute zero, this is apparently quite a slow process; probably one with significant risk of breaking something else. Sigh.)

Right. The official press release describes what happened: a circuit jumper between two adjacent magnets failed and vaporized from the current load. A whole bunch of magnets quenched (warmed up above the superconducting transition). The fried circuit jumper blew a hole in the vacuum cryostat, and also blew a hole into the beampipe itself, contaminating it.

Now they need to warm up something like thirty magnets from 1.9 K to room temperature so they can take them apart, clean out the contaminated beam pipe, and apply a fix to the interconnects. The warming process has to be extremely slow to avoid differential thermal expansion between components, which would lead to all kinds of things breaking.

They expect eight to nine months before they restart.

If you built something this big and this many billions (yes, 109 with a "b", not 106 with an "m") of dollars/euros, would you really try to turn it on at full power the very first time?

September 10 was just the date in the commissioning plan where the operators steered one bunch of protons all the way around one ring for the first time. Up to then, they were putting each bunch partway around, then dumping it, in order to adjust all of the hundreds of magnets in each arc, and all the focussing and steering magnets in the straight sections.

On 10 Sep, they successfully stored a bunch and had it circulate for a couple of hours (and repeated that feat in the other ring as well).

. Is bunch an actual quantity or are you (belatedly) trying to get down to my level?
. Hey! Quit laughing! That's a legitimate question to one who uses charm and flavor to describe stuff. heehee

You asked, "Is bunch an actual quantity or are you (belatedly) trying to get down to my level?" Yes, it is the technical term. The way we accelerate particles (electrons or protons) is that the vacuum pipe they travel through is actually a waveguide. We use RF -- generated with klystrons, the megawatt version of the magnetron in your microwave oven -- to set up standing waves in the pipe. The particles only get accelerated if they're hit the standing wave in each section at just the right phase (this is all much easier to do with pictures on a whiteboard). That naturally leads to the particle being grouped into "short" lengths centered at the maximum-acceleration phase. At SLAC the electron and positron bunches are about 6 cm long. At the LHC the proton bunches are a good fraction of a meter, if I recall correctly. By the way, not every full-wave section of the RF actually has particles being accelerated. The electric fields of a bunch can disrupt the bunch(es) behind them, so gaps are left in between to reduce that effect. Each full-wave section of RF is called a "bucket."

It occurs to me, you really ought to do an Instructable on this - How To Recreate the Big Bang in the Comfort of your own Underground Laboratory.

Seriously, it would be cool.

Or maybe a desk-top particle accelerator?

Hmmm...maybe when I have more time; that I'ble idea sounds a little bit too much like actual work :-/ Also, I'm a detector physicist, not an accelerator jock. There is an incredible amount about the details of klystron design, waveguides, superconducting vs. normal RF, image currents and wakefields, and on and on, where I pretty much know what words to put in a sentence and that's it.

As for a desk-top accelerator, check out this outstanding project. Talk about the learning experience of a lifetime!

The only reason my jaw didn't hit the floor was because my desk was in the way.

(Actually, I was thinking a not-quite-an-idiot's-guide, probably put together with stock photos you could easily get permission to use.)

Unfortunately, not until June or July of next year, after the cryomagnet debacle :-( More to the point, even the October date above wasn't quite accurate. They weren't planning to get to full beam energies and currents until 2009; even the most optimistic of braneworld theorists wouldn't claim a large enough cross-section for black hole production to get any events at first collsions.

Ah, thanks! Well then, that explains everything. Die another dayyyay, woo! I'll update the post.

Yay! Being alive is fun!