Helium Leak Forces LHC Shutdown for at Least Two Months
Written by Ian O'Neill
A series of problems forces LHC shutdown (CERN/LHC)
It's this sort of news I really did not want to wake up to. At 0927 GMT Friday morning, a fault known as a "quench" resulted in the leakage of a tonne of helium coolant causing 100 of the LHC superconducting magnets to heat up 100°C. The fire services had to be called and it was some time before engineers could access the tunnels to assess the damage. It was worse than they were expecting. Although no one was hurt and there was no danger to the public, the once-supercooled magnets were one hundred times warmer than they should be and optimal vacuum conditions had been lost. To perform repairs, the rest of the damaged sector will need to be warmed up and then slowly cooled down again, resulting in a shutdown of LHC operations for at least two months…
The leak occurred between the Alice and CMS detectors (sectors 3-4) after repairs to the faulty 30-tonne transformer were being finalized and the systems were being powered up to begin a new series of commissioning tests. According to the LHC logbooks, temperatures rose by 100°C and the vacuum required within the equipment for particle circulation to be possible was lost. Engineers had to wait for oxygen levels to return to normal within the tunnels before they could investigate the "meltdown."
Although last week's fault with the transformer caused frustration, setting LHC experiments back by a few days, scientists were optimistic the incident would have minimal effect on the first scheduled particle collisions in October. Friday's quench, however, is a serious incident, knocking the largest experiment mankind has ever attempted offline for at least two months. Although this is sad news, many scientists are keeping a positive attitude:
"This kind of incident was always a possibility with such a unique and demanding project, that’s why we were so tense on the 10th [of September]. Having seen those tantalising first signs of beam in our detectors, everyone is raring to go. So it’s really disappointing, and hard for us to keep in perspective right now. But a delay like this in a 20-year project isn't an utter disaster and I’m sure the team at Cern will fix it, and make it more robust as they go." - Prof Jonathan Butterworth of University College London, the UK head of the Atlas detector.
So what happened? The basic operating conditions for the LHC depend on very low temperatures and a very high vacuum state. It would appear both key conditions were lost as engineers tested the electrics of the LHC in the run-up to full commissioning. There was a faulty connection between two of the superconducting magnets, so when the system was switched on, the high current melted the connection, causing the helium leak. The loss of supercooled helium caused a rapid release of stored energy (an event known as a quench), heating the magnets and destabilizing the vacuum conditions.
After such a smooth start to the first proton circulation on September 10th, these setbacks may come as a surprise. However, probing the frontier of physics rarely happens without a few hiccups along the way, so let's hope this incident will be the last and we can once again look forward to the first particle collisions toward the end of the year…
Filed under: Physics
September 21st, 2008 at 8:58 pm
Hi Dave,
You're totally right, corrected now…
Cheers! Ian
September 22nd, 2008 at 12:21 am
haha that webcam link was awsome.
i love the purple tinge to the front of it.
September 22nd, 2008 at 5:27 am
# Unbeliever Says:
September 20th, 2008 at 10:47 pm
can you say "sabotage" ?
ROFLMAO
September 22nd, 2008 at 6:49 am
Check out the novel Einstein's Bridge, about a parallel universe where the Superconducting Super Collider (SSC) was built and operated. The SSC somehow made beings in another universe aware of us, and they aren't too happy with the idea of others existing even in another universe.
So the scientists have to find a way to make the SSC never happen so we don't get wiped out.
Hmmmm - of course, the SSC was much bigger than the LHC, so maybe we are still safe.
September 22nd, 2008 at 7:37 am
Astrophysical implications of hypothetical stable TeV-scale black holes
Authors: Steven B. Giddings, Michelangelo M. Mangano
(Submitted on 20 Jun 2008)
Abstract: We analyze macroscopic effects of TeV-scale black holes, such as could possibly be produced at the LHC, in what is regarded as an extremely hypothetical scenario in which they are stable and, if trapped inside Earth, begin to accrete matter.
We examine a wide variety of TeV-scale gravity scenarios, basing the resulting accretion models on first-principles, basic, and well-tested physical laws. These scenarios fall into two classes, depending on whether accretion could have any macroscopic effect on the Earth at times shorter than the Sun's natural lifetime.
We argue that cases with such effect at shorter times than the solar lifetime are ruled out, since in these scenarios black holes produced by cosmic rays impinging on much denser white dwarfs and neutron stars would then catalyze their decay on timescales incompatible with their known lifetimes. We also comment on relevant lifetimes for astronomical objects that capture primordial black holes.
In short, this study finds no basis for concerns that TeV-scale black holes from the LHC could pose a risk to Earth on time scales shorter than the Earth's natural lifetime. Indeed, conservative arguments based on detailed calculations and the best-available scientific knowledge, including solid astronomical data, conclude, from multiple perspectives, that there is no risk of any significance whatsoever from such black holes.
Subjects: High Energy Physics - Phenomenology (hep-ph); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Experiment (hep-ex); High Energy Physics - Theory (hep-th)
Report number: CERN-PH-TH/2008-025
Cite as: arXiv:0806.3381v1 [hep-ph]
Submission history
From: Michelangelo Mangano [view email]
[v1] Fri, 20 Jun 2008 12:57:24 GMT (222kb,D)
http://arxiv.org/abs/0806.3381
September 22nd, 2008 at 8:40 am
man they had put the black hole fears to rest, finally got rossler and wagner to STFU, and were getting ready to do some actual science. and now this happens! oh well i supose a device this size there are a million thing that could break
September 22nd, 2008 at 9:40 am
Lest anyone forgets, this isn't the first major failure of LHC…
(Particle Collider Magnet Failure Blamed on Faulty Engineering)
http://www.sciam.com/article.cfm?id=particle-collider-magnet
Regards,
~Michael Gmirkin
September 22nd, 2008 at 11:51 am
Michael, is this in any way related to the generation of magnetic fields by electrical vortexes?
September 22nd, 2008 at 4:05 pm
@mcenhillk: Thanks for the answer!!
And I should say, venting ultracold helium gas will additionally cause, due to the highly non-adiabatic expansion of the gas, the vent to cool down vent faster.
Reminds me of the greatest non-physicist I ever met.
Guy at a retirment home was teaching us safety precautions for, I think, oxygen tanks? Anyway, he has this pressurized bottle with gas in it, opens the valve, whoooosh, and the valve suddenly gets frost on it.
His explanation: "Because the gas in the pressure tank is at ABSOLUTE ZERO, IF NOT EVEN BELOW THAT."
I actually did not really understand why the valve cooled down so rapidly back then. But heck, yeah, I was sure that a liquid gas in a metal tank is going to be at room temperature…
September 22nd, 2008 at 6:23 pm
Oh thank god…. or what ever most physicists believe in now days. Here I was just waiting, any day now, for an event horizon to show up in my neighborhood to suck my house into a point of infinite density formally known as the LHC. Now though, I've got a two, (more likely eight), month reprieve thanks to obvious sabotage by a concerned scientist. I can finish reading my new book, and enjoy the fall foliage here in Kansas, which really just means watch the grass turn brown. So live it up people, we're on borrowed time! If the black hole doesn't get you, then 2012 certainly will. (Don't forget, 2012 is another election year, end times for sure)
September 23rd, 2008 at 12:47 am
It looks like you have changed the temperature increase to 100C, but you still state that the magnets were hot enough to boil water. Can you change it to whatever boils at -173C? :o)