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Second Snag This Week Could Delay LHC for Weeks
Posted by
Soulskill
on Sat Sep 20, 2008 12:01 AM
from the unfortunate-but-to-be-expected dept.
from the unfortunate-but-to-be-expected dept.
sciencehabit writes "After a transformer failure earlier this week, the Large Hadron Collider has hit another snag — and this one is much more serious. As Science reports, 'At least one of the LHC's more than 1700 superconducting magnets failed, springing a leak and spewing helium gas into the subterranean tunnel that houses the collider ... How long [repairs take] will depend in part on how much of the LHC must be warmed to room temperature for servicing. If it's only a short section, the repair could be relatively quick. But the machine is built in octants, and if workers have to heat and cool an entire octant, then the cooling alone would take several weeks."
Reader Simmeh contributes coverage from the BBC. We recently discussed the transformer malfunction at the LHC, which was a smaller problem and has already been fixed. Update - 9/20 at 12:52 by SS: CNN reports that the LHC will be out of commission for two months.
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LHC Shut Down By Transformer Malfunction 293 comments
Ortega-Starfire writes "A 30-ton transformer in the Large Hadron Collider malfunctioned, requiring complete replacement on the day the LHC came online. No one at CERN reported any problems, and they only released this data once the Associated Press sent people to investigate rumors of problems. I guess it's hard to just sweep a 30-ton transformer breaking under the rug."
[+]
LHC Offline Until April 2009 (Or Longer) 298 comments
rufey writes "The recent problems at the Large Hadron Collider will now keep it idle until spring 2009. The official press release is here. The LHC went offline due to a suspected failure in a superconducting connection, which overheated and caused around 100 of the LHC's super-cooled magnets to heat up by as much as 100 degrees. This resulted in the accidental release of a ton of liquid helium. The process required to repair the failed superconducting connection involves weeks of warming up the affected area from -456 degrees Fahrenheit to room temperature, and then several more weeks to cool it back down after the repair is made. The total amount of time to do this will spill over into CERN's scheduled winter maintenance/shutdown period, which is partly done to save money on electricity during the period of peak demand."
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Messin' up committee's schedule (Score:5, Funny)
The Milky Way Darwin Award Committee has to wait a bit longer before awarding the little blue ex-planet.
Re:Messin' up committee's schedule (Score:4, Funny)
If you're not nice, I'll make pro-creationism jokes next.
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Were Nielsen and Ninomiya correct? (Score:5, Interesting)
Or, similarly, observer-selection of broken LHCs? (Score:5, Insightful)
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Re:Or, similarly, observer-selection of broken LHC (Score:5, Interesting)
http://en.wikipedia.org/wiki/Many-minds_interpretation [wikipedia.org]
Only minds that exist can observe; only minds that have not been destroyed by the LHC can exist. So, if the LHC really destroys the earth we'll keep observing it not functioning correctly.
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Re:Give me a bag (Score:5, Funny)
When _I_ turn something on, I set it up completely first, leaving only one final connection incomplete. That connection is made by an enormous knife switch, which I throw to the dramatic dimming of lights (managed by my assistant; my invention is of course on another power source entirely), sparks, and the scent of ozone. THAT is how you turn something big on.
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Argh, Matey! (Score:5, Funny)
Thar she blows, ye scalleywag... doewn beluw deck she's spewin colder then the centre o' hell.
Mark me wards... there's trouble brewing... somethin strange and black. Beware, I say... beware!!!
That's a lot of helium... (Score:5, Funny)
All I could envision was a bunch of physicists coming out of the tunnel squeaking like chipmunks.
I have nothing to contribute but a cheap laugh and for that I am sorry.
Liquid Helium Piping (Score:5, Interesting)
Re:Liquid Helium Piping (Score:5, Informative)
There is not just one line. There are 6 lines as far as I know. They transport superfluid helium as well as warm helium. Here is a paper about the cryo system:
http://accelconf.web.cern.ch/AccelConf/e96/PAPERS/ORALS/THO04A.PDF
Anyways, they are now investigating with a remote inspection train that can travel in the LHC.
Paper accessible here:
http://accelconf.web.cern.ch/accelconf/p07/PAPERS/MOPAN076.PDF
Sorry but I am going to an anonymous coward -- but clearly, this post comes from CERN...
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So what? (Score:5, Insightful)
Re:So what? (Score:5, Funny)
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the octant? (Score:5, Funny)
oh i know this level
just beyond the dead space marine after you open the first door (watch out for the imp sniping at you from above) there's a false panel marked "UHC" (not "LHC") on your left. shoot that with your pistol and it opens. but shooting your pistol will wake a cacodemon further down the hall
easy
Cyro status: sector 34 at 20K-80K (Score:5, Informative)
You can look at much LHC status online, including detailed cyro status. (I'm not giving the URL, so as not to Slashdot that server. You can find it if you really care.) Sector 34 of the LHC is at sector 34 at 4.5K-20K, instead of down below 4.5K where it should be. One of the magnets quenched and went normal, and much of the energy in the magnet is dumped as heat. Then the liquid helium boils to a gas and blows out through relief valves. But the sector hasn't been brought up to room temperature, so they apparently think they can fix the problem without major work on the magnet.
Some of the cyrogenic magnets gave serious trouble last year, but apparently it's not as bad this time.
This is what a 'quench' is... (Score:5, Informative)
If you are not familiar with superconducting magnets, then some of these terms may seem a bit mysterious. So, here goes...
A superconducting magnet is essentially a big coil of superconductor. Initially, you put current into the superconductor to build up the magnetic field. You then 'join the ends' of the superconducting loop, so the current circulates endlessly, and the middle has a constant magnetic field.
There is a lot of energy in the magnetic field. An 11-tesla magnetic field has about the same energy per unit volume as TNT. Worse than TNT, there is no rest mass to the 'explosive' so all the magnetic field energy would be dumped straight to the surround. The surround is already under a lot of tension due to the magnetic field, so the magnet would blow apart spectacularly, if it wasn't properly designed.
The magnet has a link in the superconductor which is heated to drive it 'normal': this is used when the magnetic field is being built up. This link usually has a great big conventional shunt resistor in parallel with it with great big heat sinks, and this arrangement is usually on the top of the magnet. If the helium level gets low or something else funny happens, the hope is that the coil superconductivity will go at this point rather than anywhere else. The magnetic energy, instead of getting dumped into the magnet's structure, gets dumped into this shunt resistor. It may glow yellow, and boil off lots of helium, but the magnetic field can collapse over a few seconds rather than instantly, and won't release an electromegnetic pulsed that might set off a chain reaction with the magnets next door.
What has happened here is that the safety system has gone off in one of the magnets just as it ought to. I expect they will inspect the shunt assembly to check nothing has scorched when all the energy got dumped, and also to try and find out why it did. However, with luck they can get it all going again without interrupting the vacuum.
Doomsday Device (Score:5, Interesting)
This makes me think of the great SF story "Doomsday Device", by John Gribbin (Analog, Feb. 1985 -- unfortunately not available online, AFAIK). In that story a powerful particle accelerator seemingly fails to operate, for no good reason. Then a physicist realizes that if it were to work, it would effectively destroy the entire universe, by initiating a transition from a cosmological false vacuum state to a lower-energy vacuum state. In fact, the accelerator *has* worked; the only realities the characters experience involve highly unlikely equipment failures. (Thus, a many-worlds physics is shown to be correct.) It's further revealed that the world has been "anthropically steered" in the past by arranging for it to be destroyed when things are not going well.
Re:sabotage (Score:5, Insightful)
I would be surprised. Shit happens.
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Re:sabotage (Score:5, Insightful)
I would have been amazed if a structure as complex as this worked the first time the switch was thrown. Think about how simply enormous the LHC [wired.com] is. It has miles of wire, gigantic magnets that have to be perfectly synced and placed with amazing accuracy. It's not like LHCs are turned out every week. Gigantic super colliders are HARD to build.
They'll eventually iron out all the problems and can proceed to cause the world to end.
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Re:sabotage (Score:5, Funny)
Fuck, I can't even get Hello World to work on the first compile most of the time.
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Re:sabotage (Score:5, Funny)
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Re:Is this indicative of something? (Score:5, Informative)
Yes, because taking nearly 30 years to build this was rushing.
Calm down, one of the magnets quenched. When that happens, it gets REALLY hot and things break. They knew it could happen.
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Re:Is this indicative of something? (Score:5, Insightful)
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Re:Is this indicative of something? (Score:4, Insightful)
And even if it does turn out to be completely useless for physics, I would have much rather have seen my US tax dollars be wasted on something like a particle collider than how they've been wasted in Iraq. Money spent on science is almost never truly wasted.
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Re:Is this indicative of something? (Score:5, Informative)
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Re:ohno! (Score:5, Funny)
For the slashdotters who haven't yet seen the CERN webcam images of the leak occuring:
http://www.cyriak.co.uk/lhc/lhc-webcams.html [cyriak.co.uk]
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