Demystifying the LHC shutdown
March 11, 2010 | 11:11 am
Yesterday the science news media and twitterverse were abuzz following a BBC News article announcing “LHC to shut down for a year to address design faults.” Readers – and the news outlets that frantically re-reported the BBC article – assumed that CERN had found a new problem with the LHC and announced an imminent shutdown. Neither is the case. Here, we join our fellow science writers and bloggers in setting the record straight about the LHC’s next long shutdown.
The LHC will shut down for about one year – but not until late 2011
What the BBC reported yesterday is true, but is not exactly news. A revised schedule for the LHC’s next few years was announced in early February by CERN. According to the revised schedule, the LHC will run at a maximum energy of 3.5 TeV per beam for a period of about 18 months, starting with the first collisions at 3.5 TeV per beam expected to take place at the end of this month. The long run will end in late 2011 or when the LHC experiments have collected a certain quantity of data (one inverse femtobarn in particle-physics parlance), whichever comes first. At the conclusion of this long run, the LHC will shut down for about one year.
The shutdown will be used to fix problems with the LHC and carry out routine maintenance
The long length of the next major LHC shutdown is due to two main factors: the time necessary to fix problems with magnet connections that currently prevent the LHC from running at its full energy; and the time needed to prepare the LHC for routine maintenance and repair work and then restore the LHC to operational status.
Particle accelerators are incredibly complex machines, and, like any complex machine, require regular maintenance to keep their parts running smoothly, repairs when parts wear out or break down, and occasional upgrades to increase the machine’s performance. Maintenance, repairs and upgrades to the LHC cannot take place while the machine is running, for two reasons. One, the radiation generated in the immediate vicinity of the LHC while it is operating means that technicians cannot enter the LHC tunnel while the machine is running. Two, the LHC’s magnets must be cooled to almost absolute zero to bend high-energy beams of particles, and it takes about one month to warm the accelerator up to room temperature before technicians can access the magnets’ innards.
In the past, CERN – like Fermilab near Chicago, which also operates a supercooled particle collider – ran its accelerators on a one-year schedule. The accelerator ran continuously for eight or nine months, followed by a four or five-month shutdown for maintenance, repairs, and upgrades. But the LHC is unique in that it contains 27 kilometers’ worth of supercooled machinery. (CERN’s previous 27-kilometer-long accelerator wasn’t supercooled, and Fermilab’s is less than 7 kilometers around.) As the LHC takes at least one month to warm up, and another month to cool down, CERN has decided to move to longer running times followed by longer shutdowns.
But the warm-up and cool-down times aren’t the only reason that the LHC’s next shutdown will be lengthy. The 2011-2012 shutdown will also be used to fix problems with the connections between superconducting magnets that prevent the LHC from running at the energies it was designed for. On September 19, 2008, a superconducting connection between two LHC magnets melted, resulting in a chain reaction that damaged more than 50 magnets. The damage took more than one year to fix, and spurred a critical review of the LHC’s design. The result was the decision to run the LHC at half design energy – 3.5 TeV per beam – long enough to give the LHC experiments enough data to remain competitive with Fermilab’s Tevatron experiments in the hunt for the big physics discoveries. And then take all the time necessary to fix the LHC so that it can finally ramp up to its full energy of 7 TeV per beam in 2013.
Katie Yurkewicz
Posted in LHC updates |
5 Comments »
March 11th, 2010 at 4:23 pm
The science journalism got another bad grade. There have been lots of new reports about “new problems” with the LHC that will be shut down although the “news” is from February. People clearly copy from one another.
However, some of them – the Age in Australia and its followers – wrote some additional details about the copper connectors which seem to be un-ready for sqrt(s) = 14 TeV. Is that right? Will it be a difficult operation to fix this?
March 12th, 2010 at 2:52 am
Lubos,
It’s correct that the superconducting connections between LHC magnets – of which the copper stablizers are one part – need more work before the LHC can run at 7 TeV per beam.
In a press release issued by CERN last year (http://press.web.cern.ch/press/PressReleases/Releases2009/PR13.09E.html) they mentioned the problem of the copper stabilizers. In 2009, repairs were made to these connections that will allow the LHC to run safely at 3.5 TeV per beam – half it’s design energy. More repairs are needed to the superconducting connections before the accelerator can run at 7 TeV per beam. These repairs will be carried out during the long shutdown to start at the end of 2011.
Another good writeup about the problems with the superconducting connections can be found in Nature News (http://www.nature.com/news/2010/100223/full/4631008a.html). Or for a technical paper: http://iopscience.iop.org/0953-2048/23/3/034001/.
March 12th, 2010 at 9:12 pm
Deplorable media coverage when this ‘BBC story’ was announced over a month ago by Steve Myers, Head of Accelerators and Technology at CERN just after the Chamonix Conference end of January.
There was much more of interest like the surprising lack of foresight by CERN for 10 to 15 years in considering mounting radiation hazards in LHC tunnels, which as Meyers also announced, will cost SF 100 Million just for civil engineering to move power supplies at risk. See “Large Hadron Collider Waiting For Doomsday” in NewsHammer.
On another safety angle, CMS data from December shows extra mesons produced at 2.36 TeV, 10% or 14% more depending on the model used by CMS Collaboration. According to Professor Richard Shurtleff of WIT, this could have a cause, rather than an odd uplift at higher energies. He postulates a Trajectory Energy added, due to interactions with Earth’s gravity.
His calculations suggesting energies were actually 2.52 TeV and sent by him to CMS, are published with his permission in NewsHammer. They are attached to my article “Scrubbing CMS Data At The LHC” that discusses his work and also my idea of added magnetic Trajectory Energy, possibly demonstrated by the CMS solenoid’s 3.8 Tesla magnetic field acting on beams and boosting their energies as was observed by CMS and Meyers. Also see the lead-in to Shurtleff in my earlier “Fantastic LHC Energies May Be Higher Than Expected” in NewsHammer.
Shurtleff is still awaiting a reply from CMS and would appreciate comments.
Other observations by Shurtleff on beam/collision boosts I’ve received privately, are pending his approval for publication in NewsHammer.
Since Fermilab has a special connection to CMS, would anyone care to comment on what the extra production of kaons and pions was at CMS? It’s important as strange atoms could be produced and strangelets too.
CERN is silent on this.
The point is LHC safety. I’ve written 24 articles in a spirit of fun and cooperation that were cautionary on LHC Machine risks in The Science Of Conundrums, before the Massive Quench of 2008. Another series of reports recently.
It won’t serve anyone to ignore risks when it means the future of particle physics. If the LHC has another accident that could be prevented like the one in 2008, it could mean the self-destruction of the LHC.
Imagine significantly more powerful beams and collisions that the LHC Machine cannot control. Or the unexpected production of stable Collider Objects even at 7 TeV collisions? The LHC has already had a beam loss and beam explosion this December. The next incident could be at triple Tevatron energy.
According to CERN Commissioning, there is no plan to duplicate 2.36 TeV collisions. Some test collisions at 0.90 TeV before the ramp up to 3.5 TeV beams and 7 TeV collisions March 30, 2009. Why the hurry for glamorous results?
I’d like to thank Fermilab, Symmetry and SymmetryBreaking for their excellent work and support of the LHC (including major participation in the outside review of the 2008 accident, the LHC Risk Panel and its important findings and advice) while providing an open news and discussion forum on the LHC, which I don’t see anywhere at CERN. Too much selling of CERN product at CERN and not enough interest in the public’s need to know and that includes your own community at Fermilab/ SLAC.
–Alan Gillis
March 12th, 2010 at 11:19 pm
Actually, in many parallel universes, the LHC was run at full power, and the resulting black holes destroyed the Earth. We’re still here because in our universe, the LHC had problems preventing it from running at full power. Hakuna matata!
February 23rd, 2011 at 9:00 am
I’ll be honest, I can’t see much of a reason in keeping the LHC operational,yet at half capacity when this is already happening at ‘competing’ facilities. Personally i would focus on getting the repair work underway, then start at full 7 teV+.. where we can maybe start to see some real results.