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A psychological Deep Impact
:: 16 January, 2009
First was a faulty transformer, then liquid helium leaked. The LHC will be at least until April stand still. Probably will be more breakdowns happen.
From the LHC, the giant particle accelerator in the European nuclear research center CERN in Geneva, physicists hope that the new findings about what that matters. With the huge machine, which has a 27 kilometer long tunnel ring is housed, they want to discover new particles and matter in a state, as he immediately after the Big Bang in the many billions of degrees hot universe reigned.
They shoot them in the accelerator ring protons in two opposing beams together. The collisions of the particles released energy is so high that a new particle cloud created. From their orbits and decay properties can be attributed to their physical properties. Thus, the researchers learned much new about the basic laws of nature in the universe.
Disturbance to a magnet
Unfortunately, the findings still waiting left. For a breakdown put the LHC now hors de combat. On 10 September the CERN physicists their giant machine into operation and a first proton beam into one of the two nozzles geschleust. In the following days, they continued the trial run - up to 11:27 on the clock Friday last week. At this time, just as tests of the electrical circuits of the LHC ran, the gauges registered a fault.
As it turned out, had a magnetic heated, and one to two tons of liquid helium were expired. The noble was minus 271 degrees Celsius cold, which is 1.9 degrees above absolute zero. Some 120 tons of helium to circulate in the LHC. Which serve about 90 tonnes, which some 1200 superconducting magnets to cool, the proton beams and to combine their Kreisbahn force in the jet in which a high vacuum. Per cubic centimeter found it less than atoms in the near-Earth space. The remaining 30 tons of helium can be found in pipes and refrigerators.
Explosives in the underground
In superconducting coil reduces the electrical resistance to almost zero. Only then can the strong currents flow loss for the production of the huge magnetic fields in the accelerator ring is needed. The coolant outlet meant that the affected magnets around 100 degrees warmed. But the sector was 34, in which the liquid helium spilled, frozen and looked after data from a CERN spokesman like a Eistunnel. The segment includes one-eighth of the ring length. The CERN researchers deemed the incident as so serious that they alerted the fire brigade. In fact, liquid helium, which is heated and evaporates quickly, such as explosives act, because it multiplies its volume. Its boiling point is minus 269 degrees Celsius
The incident occurred just a day after CERN engineers repaired a faulty transformer and the blasting operations had resumed. Now the LHC has been shut down again, and the search for the cause of the leak began. A preliminary analysis showed that probably an electric cable between two magnets was blown. As a result, a total of ten sunken magnets, but may also have been much more.
The slow increase in room temperature
To precisely identify the cause and repair the damage, the affected sector must now be at room temperature, and only then can open the damaged magnets. This process takes three to four weeks. It must be slow, otherwise the warming caused further damage, such as components expand. The repair is expected, according to CERN's press office until the regular winter maintenance period of the particle ejection come. Therefore, the reopening until the spring of 2009 to be expected. "The fact that the accident immediately after the successful launch of the LHC occurred, is undoubtedly a deep psychological blow," said CERN Director General Robert Aymar. "I do not doubt that we overcome the setback will be."
Tags: liquid helium , LHC , particle accelerator , European nuclear research center , CERN ,
