After the devastating quench incident on September 19 of last year, resulting in the rupture of the cryogenic vessels within the LHC magnets , CERN has worked furiously to repair the damage, prevent any future similar failure, and get the LHC back to its commissioning program. Following a meeting of technical experts and the leadership in Chamonix, France last wee, the CERN Directorate has issued a press release with the new plan for LHC restart:
The CERN Management today confirmed the restart schedule for the Large Hadron Collider resulting from the recommendations from the Chamonix workshop. The new schedule foresees first beams in the LHC at the end of September this year, with collisions following in late October. A short technical stop has also been foreseen over the Christmas period. The LHC will then run through to autumn next year, ensuring that the experiments have adequate data to carry out their first new physics analyses and have results to announce in 2010. The new schedule also permits the possible collisions of lead ions in 2010.
This new schedule represents a delay of 6 weeks with respect to the previous schedule which foresaw LHC “cold at the beginning of July”. The cause of this delay is due to several factors such as implementation of a new enhanced protection system for the busbar and magnet splices, installation of new pressure relief valves to reduce the collateral damage in case of a repeat incident, application of more stringent safety constraints, and scheduling constraints associated with helium transfer and storage.
In Chamonix there was consensus among all the technical specialists that the new schedule is tight but realistic.
The enhanced protection system measures the electrical resistance in the cable joints (splices) and is much more sensitive than the system existing on 19 September.
The new pressure relief system has been designed in two phases. The first phase involves installation of relief valves on existing vacuum ports in the whole ring. Calculations have shown that in an incident similar to that of 19 September, the collateral damage (to the interconnects and super-insulation) would be minor with this first phase.
The second phase involves adding additional relief valves on all the dipole magnets and would guarantee minor collateral damage (to the interconnects and super-insulation) in all worst cases over the life of the LHC. One of the questions discussed in Chamonix was whether to warm up the whole LHC machine in 2009 so as to complete the installation of these new pressure relief valves or to perform these modifications on sectors that were warmed up for other reasons. The Management has decided for 2009 to install relief valves on the four sectors that were already foreseen to be warmed up. The dipoles in the remaining four sectors will be equipped in 2010.
That the delay would be a year, in total, was not unanticipated given the magnitude of the incident, and the good news here is that the root cause is now believed to be understood. The retrofit to the quench detection and pressure relief systems should prevent this from happening or causing such great damage in the future.
Hopefully this was the worst of the birth pangs of the LHC! With such a complex and enormous machine, however, it would be overly optimistic to hope that it will be the last.
The experiment I work on, CMS, is open now and in March we are going to remove the innermost detectors, the forward pixels, do minor repairs, and reinstall them by mid-April. We are taking advantage of the fact that so far, anyway, the detectors have not become radioactive from high intensity beam, after which any work on them will be far more difficult.
And, we are preparing to do the physics once we do get data. The extra year, though painful, gave us extra time to refine our approaches, and physics will emerge faster as a result, I believe.
February 9th, 2009 at 5:45 pm
Why does CERN host this workshop at Chamonix (a ski resort town in the French Alps) rather than, oh I don’t know, maybe hosting it at CERN?
February 9th, 2009 at 6:56 pm
Because that’s where the EUROPEAN organization CERN wanted to have it.
February 9th, 2009 at 7:16 pm
Ciaobella, physicists simply work together better at ski resorts. Haven’t you ever noticed the reduced friction there?
February 9th, 2009 at 10:30 pm
This seems reasonable.. as long as it doesn’t slip too much. the biggest
concern is that things don’t go *horribly awry* again of course, so as
long as there is some not crazy amount of delay, and we do start getting
some collisions this year, i think the large majority of physicists and
physics fans around the world will feel all was worth the delay… I profoundly hope.
February 9th, 2009 at 10:33 pm
You’ll note that our technology is not sufficiently advanced, because it can be distinguished from a rigged demo.
February 10th, 2009 at 8:08 am
will there be just one electron kicked of the Pb atom and accelerated
or do they try to kick off more electrons so that acceleration is faster
if it is faster ?
on those enegy levels, is it still true that a bigger rock makes bigger waves?….one PB atom makes more debree that a cloud of protons?
February 10th, 2009 at 9:10 am
[...] Een heliumgekoelde magneet in de LHCDe Large Hadron Collider, de grootste deeltjesversneller ter wereld van CERN bij Genève, gaat vermoedelijk september dit jaar weer van start. Aldus een bericht van de directie van CERN dat gisteren de wereld in werd geslingerd. September wil men eerst rustig proefdraaien en kijken of alles goed gaat en in oktober moeten de eerste echte botsingen tussen de protonen plaatsvinden. Zoals bekend kreeg de LHC op 19 september 2008 te maken met een ernstige heliumlekkage, 9 dagen na de opening. Sinds die tijd zijn technici druk bezig de schade aan sector 3-4 van de tunnelbuis te repareren, apparatuur te vervangen én last but not least te voorkomen dat een dergelijke lekkage zich in de toekomst weer voordoet. Mmmm, lijkt mij wel handig ja. De LHC zou overigens volgens een eerdere planning al in juli van start gaan, maar door allerlei strengere veiligheidseisen en de daaruit volgende noodzakelijke handelingen is die datum naar september verschoven. In 2010 hoopt men de eerste wetenschappelijke resultaten te kunnen melden. Nou, afwachten maar weer. Bron: Cosmic Variance. [...]
February 10th, 2009 at 11:32 am
Wilfred: when they do heavy ion collisions, my understanding is that they are fully ionized. (I could be wrong…)
February 12th, 2009 at 2:01 pm
Here’s hoping that Obama will be setting aside some funds for the International Linear Collider, rather than consider a new SCSC. It’d be pointless to compete to be first to the Higgs+. Better to collaberate and get more bang for the buck.
February 17th, 2009 at 4:42 pm
[...] Large Hadron Collider should be lurching back to life this year, but the Tevatron at Fermilab might yet have a last hurrah. While the LHC is still fixing [...]
February 18th, 2009 at 8:20 am
Wilfred: John is right. By the time the lead ions get into the LHC, all the 82 electrons will have been removed, leaving only lead nuclei. These nucleus-nucleus collisions will have 82 times the energy of the protons. The energy is a bit less concentrated than in the proton collisions but the purpose is to study more extended volumes (still extremelay tiny by normal standards) of VERY hot matter, the so-called quark-gluon plasma.
February 24th, 2009 at 4:06 pm
[...] the LHC, for all aspects of the accelerator. Reports have appeared on the blogosphere, for example here and [...]
March 13th, 2009 at 9:00 pm
[...] up? Is there a race at all? Can the Tevatron see it before the LHC, given that the LHC has been delayed a year due to the quench incident last [...]
March 31st, 2009 at 6:13 pm
I have found great amusement in the give-and-take of scientific minds involved in this “race for the Boson”.
Maybe Obama himself could help his European friends and provide a little “stimulus” package to buff out the potholes. Come on over, it’s a free show!