The mammoth Large Hadron Collider is offline after a pretty big malfunction during testing. CERN, the agency in charge of the LHC, has released its preliminary findings of what happened.
The current flow in the LHC depends critically on it being a superconductor. That means the electricity flows with almost no resistance (think of it like water flowing in a pipe that has no friction). For some reason — why it happened is still unknown — a small patch of resistance developed in the circuit. If left alone, something like this can cause massive damage; for example electricity flow can generate a vast amount of heat in such a patch. However, the LHC automatic safeguards kicked in, and appeared to work as designed.
However again, an electric arc was triggered, and we’re not talking about a little spark. It was big enough to punch a hole in the dewars containing the liquid helium needed to cool the magnets down to superconducting temperatures. The helium leaked out, and started to fill a region of the LHC which is supposed to be kept in vacuum. It also leaked out into the tunnel holding the LHC itself, causing some damage to the structure, including partially tearing the 1 ton magnets out of their brackets holding them down.
Yikes. So there is some mechanical damage, but it’s limited to where the problem occurred (other magnets appear to be fine). About 30 magnets were damaged, and they lost about six tons of helium, which needs to be replaced. The repair will take some time, as will figuring out exactly what happened, and, more importantly, why.
They’re being cautious about this, as you might expect:
Although the cause of the initial growth of connection resistance has not yet been established, and knowing that a similar event has not occurred in the test of all other sectors and of their thousands of connections, it has nonetheless been decided that additional measurements to generate early warnings and interlocks, improvements in pressure relief devices and in external anchoring of the quadrupole [magnet] cryostats with vacuum barrier will be implemented before any further powering of the LHC circuits at high current.
So they will proceed carefully, but I’m guessing they will have it up and running in a few months time, certainly sometime next year. This is a major setback for the program, of course, and will cost them time, money, and some PR, no doubt. But they will get it back up to speed, and soon they’ll be back in the business of science, poking and prodding the Universe on a quantum scale.
October 19th, 2008 at 10:28 pm
So was that big arc a plasma.
October 19th, 2008 at 10:33 pm
Any pics?
oh wait…lol :b
October 19th, 2008 at 10:33 pm
“About 30 magnets were damaged, and they lost about a ton of helium”
How many people can get a high squeaky voice from a ton of helium?
October 19th, 2008 at 10:46 pm
Watch…
Someone will blame black holes.
October 19th, 2008 at 10:49 pm
Right now I am wondering how much heluim that would make pigs float.
October 19th, 2008 at 10:56 pm
A ton of Helium: How do they know? How do you get helium to stay on the scales?
October 19th, 2008 at 11:18 pm
I can’t wait until the LHC is back up and running, and we start getting some results in…. What an exciting time for science!!!!!!!
On a totally related note (exciting time for science), Phil, the Death From The Skies! countdown clock says 43 minutes!!!!! Can’t wait!!!!!
October 19th, 2008 at 11:27 pm
A ton of Helium: How do they know? How do you get helium to stay on the scales?
They put the scale on the ceiling… just like Spider-pig.
October 19th, 2008 at 11:51 pm
They lost 6 tonnes of helium – 2 tonnes rapidly and another 4 tonnes slowly.
From the report: https://edms.cern.ch/file/973073/1/Report_on_080919_incident_at_LHC__2_.pdf
“About 2 t of helium, corresponding to the volume contained in the magnet cold mass of subsectors 19-21, 23-25 and 27-29, were rapidly discharged and eventually released to the tunnel, producing a cloud which triggered the oxygen deficiency hazard detectors installed on the tunnel vault and tripped an emergency stop, thus switching off all electrical power and services from sector 3-4. In the subsequent leakage from the open circuits, and before restoration of electrical power enabled to actuate cryogenic valves, another 4 t of helium were lost, though at much lower flow rates. The total loss of inventory thus amounts to about 6 t, out of 15 t initially in the sector.”
October 20th, 2008 at 12:00 am
Phil, your book countdown clock is about to read midnight your time, but over here in the UK it’s already bloody 7:00 a.m.!
October 20th, 2008 at 12:07 am
I hate Monday’s!
October 20th, 2008 at 12:17 am
A Large Hadron fail… I’m sure they can do something for that now
October 20th, 2008 at 12:36 am
As everyone knows in the center of a blackhole all physics breakdown so time travel is allowed. So in the future when the LHC fires up and does it first experiment a micro blackhole is formed. As soon as the blackhole gains enough mass it travels backward in time. It travels back to the original try to start up and goes down the stream and then is held up and creates resistance. Then the machine is turned of and the blackhole jumps to the heluim container. Then the blackhole jumps back to 13.8 billion years and then explodes creating the universe. When will this all happen 2012, also the the universe will be created by and intelligent designer.
October 20th, 2008 at 12:50 am
lol Davidlpf
October 20th, 2008 at 1:02 am
They may not have camera footage but if they did I bet it would look something like this. Let’s hope they arm their poor techs w/ crowbars…
October 20th, 2008 at 1:04 am
Hahaha, I like the idea of the “intelligent designer” creating the universe quite by accident.
October 20th, 2008 at 2:55 am
This is the hardest concept to get people to understand about science: failure is expected, and can sometimes yield more positive results more quickly. It is through failure, negative results, and eliminations that true progress is made. As a result of this failure the repaired LHC will be safer & more robust, which is no bad thing. And all future engineering projects on this scale can benefit from what was learned about how this failure occurred.
One more time, for the cheap seats: failure is required for science to function well.
October 20th, 2008 at 3:19 am
loss of a metric tonne?
that is about 8m³ or 8000Litres of liquid He.
Turned gaseous this equals to about 5900m³ at 15degC.
Assuming a lung capacity of say 4Litres, this will allow for
1,475,000.00 portions of squeaky voice.
October 20th, 2008 at 3:29 am
Actually, given the complexity of the system you have to expect some kind of failure this early on – a lot of moving (well, kind of moving) parts and some unknowns thrown into the mix. I’m just glad it wasn’t worse & caused even more damage – still looking forward to seeing this thing move forward & get some exciting results from the experiments.
October 20th, 2008 at 3:35 am
Ouch, I’d hate to be on the receiving end of a liquid helium leak.
October 20th, 2008 at 3:47 am
I’m sure we all wish the teams at CERN the very best.
I heartily approve of their cautious approach. The LHC is so important that their thoroughness is sure to pay off in the long run.
October 20th, 2008 at 4:32 am
# MichaelL Says:
A Large Hadron fail… I’m sure they can do something for that now
Vigara?
J/P=?
October 20th, 2008 at 4:54 am
Lots of funnys here,,,
Wonder how well they vet their construction crews. It only takes one whack job Luddite, to undermine everyones work. I doubt sabotage as a causitive factor, but then I also don’t trust Luddite activists to just keep their hands in their pockets, when they believe “them evil scientisks is gonna dee stroy the whirled,,,”.
A story here, anyone,,,???
GAry 7
October 20th, 2008 at 6:34 am
Better to deal with a few small Gremlins in the system now (as opposed to maybe some bigger ones down the road).
I guess those spare breathing tanks that the tunnel workers are required to carry with them are a pretty good precaution after all.
And I second what Nigel said!
October 20th, 2008 at 6:56 am
Yikes, CERN is now saying it looks like it’s north of 6 tons of Helium released. And they found particulate matter in the beam tunnels that will have to be cleaned out. Hopefully that’s it though.
October 20th, 2008 at 7:05 am
Most of the folks in this area have another theory: Goddidit.
October 20th, 2008 at 7:11 am
Dave,
In order to weigh helium, they mount the scales on the ceiling.
October 20th, 2008 at 7:13 am
Note to Self:
Read the whole thread before commenting.
Thomas got the ceiling scales joke in before me. Sorry for the repeat.
October 20th, 2008 at 7:17 am
It wouldn’t surprise me if some interesting science comes out of the failure itself.
October 20th, 2008 at 7:52 am
From the article:
“During the ramping-up of current in the main dipole circuit at the nominal rate of 10 A/s, a resistive zone developed leading in less than one second to a resistive voltage of 1 V at 9 kA”
Ramping up at 10 amps per second? Failed at 9kA? that’s a lot of current. Now wonder it blew a hole in things. And I can see why they shut it down in the winter to save electricity. I think Cern needs its own nuclear reactor.
October 20th, 2008 at 8:22 am
Phil Evans thanks for the update. I had originally heard one ton, and hadn’t seen any different numbers.
October 20th, 2008 at 8:58 am
I can’t help but imadge-ine all those scientists and engineers and technicians running around shouting in helium fuelled high pitched munchkin voices!
October 20th, 2008 at 9:25 am
I’z on yore planet! Waysting all yore heliums!
Seriously though, whenever I hear how limited our helium supply is on earth, it’s disconcerting to think about how much is lost through kid’s balloons over time.
Since I don’t have a joke about weighing helium, I’ll just answer the question. A simple proportionality relationship for the amount of a gas is available in the form:
PV=nRT
P=Pressure; V=Volume; R=is a constant; T=Temperature; and finally n=moles of gas.
This of course applies to an ideal gas, and it can get more complicated, but it works well enough for the average interested person. For helium, we look up the molar mass on the periodic table (the molar mass determined by experiments with a mass spectrometer or other means) and after working out n using the formula above we simply divide n (in moles) by that molar mass. Voila! We know have the number of grams of Helium, which we then convert to tons.
PS to Phil- When you use as many links as I just have, a “Preview” function for comments would be appreciated. Just sayin’
October 20th, 2008 at 10:58 am
Wow are we running out of Helium again? I’ve read about worries over Helium shortages in articles dating back to articles in Science magazines and articles in the 1920s. Where did Helium shortage worries come about? World War 2? Sure it’s not exactly Hydrogen but its defintly not Astatine either.
October 20th, 2008 at 11:03 am
“was big enough to punch a hole in the dewars containing”
Dewars? This thing is wrapped in Scotch? The LHC gets more awesome all the time.
October 20th, 2008 at 11:13 am
LOL @ skeptigator
This is based in Switzerland-France. I’d say more likely Coqnac 
From Merriam-Webster:
Main Entry: dew·ar
Pronunciation: \ˈdü-ər also ˈdyü-\
Function: noun
Usage: often capitalized
Etymology: Sir James Dewar
Date: 1939
: a glass or metal container made like a vacuum bottle that is used especially for storing liquefied gases —called also Dewar flask
October 20th, 2008 at 11:13 am
Actually, in the superconducting state the electricity flows with exactly zero resistance. This is why the quenches are so violent – from zero to something at 9 kA is a big freaking change.
October 20th, 2008 at 11:22 am
It is a lot of current Heinz, BUT since we’re talking about superconductors, you can hit that kind of current at very very small voltages. The resistive voltage it hit when the spot went south of superconductivity was 1 V remember, so even during the failure (when it was drawing WAY more power than it should) it was only using 9 kilowatts or so. For comparison, my parent’s household draws about 4 kilowatts without the air conditioning on.
(They have a load meter, and it actually uses sane units… I mean kilowatt-hours for total usage? Seriously? Why would you mix time units like that (J*hr/s)? Why not measure in megajoules? It’s only different from kWh by a factor of 3.6…. but that’s just a pet peeve)
October 20th, 2008 at 11:32 am
Indeed DG, though there is a subtlety in that the overall circuit has non-zero resistance, since you still pick up a little resistance since it’s got to be hooked up to non-superconducting source SOMEWHERE that has internal resistance (since a superconductor cannot support a potential difference, a superconducting voltage source doesn’t seem to make sense, (AC or DC)). Though I could just be wrong. Superconductivity is not something I’ve spent a lot of time studying, aside from the idealized conductors one plays with in E&M courses.
October 20th, 2008 at 11:50 am
I seem to remember watching a History channel show about Zeppelins in which the commentator stated that the reason the Germans had to ues hydrogen was because the majority of the worlds supply of naturally found helium was in the United States and they wouldn’t sell it in the 30’s. Where do you find “naturally found helium”? Is it still true? The helium that excaped is still in the atmosphere, so can helium be extracted from the atmosphere or is that just too impractical to consider. Are the Americans the cartel of the helium world?
October 20th, 2008 at 12:17 pm
The reason helium only seems to get scarcer is that while Helium is a natural nuclear decay product, it’s so light is floats off where we can’t get our hands on it. It is collected in the same pockets where natural gas is found, tying helium prices and scarcity to fuel prices.
Argon, by contrast, is heavier so it sticks around as one percent of our atmosphere.
As for Germany, remember that it was consistently being blockaded by the end of the war, and that external supplies of gas were being cut off. This is why Germany was so reliant on coal gasification-liquification to obtain fuel. Then you also have to remember that a Zeppelin’s appeal was as a high altitude, relatively stealthy bomber. However by WWII, the ceiling for fighter planes was elevated. Hydrogen or helium, zeppelins are still huge slow moving and poorly armed targets. In other words- obsolete.
October 20th, 2008 at 12:41 pm
@The Chemist
Thanks for the info about helium and natural gas. I didn’t know that. I was actually referring to the time between the wars when Zeppelin was competing against ocean liners for transatlantic traffic. However Zeppelins are making a comeback as heavy lifters for freight.
October 20th, 2008 at 3:21 pm
Boy, I sure hope they get the REST of their calculations correctly. . . .
October 20th, 2008 at 8:05 pm
[...] CERN releases preliminary failure analysis | Bad Astronomy | Discover Magazine The current flow in the LHC depends critically on it being a superconductor. That means the electricity flows with almost no resistance. For some reason — why it happened is still unknown — a small patch of resistance developed in the circuit. If left alone, something like this can cause massive damage; for example electricity flow can generate a vast amount of heat in such a patch. However, the LHC automatic safeguards kicked in, and appeared to work as designed. [...]
October 23rd, 2008 at 5:30 am
Brian Hamilton said:
Yeah, it may only have been 9 kVA, but I guess, depending on what caused the resistance, that could have been concentrated into a small volume and hence be considerably more dramatic than the use of 9 kW by domestic appliances.
November 1st, 2008 at 12:28 pm
[...] CERN Releases Preliminary Failure Analysis [...]