Photo from: elementy.ru
Schematic view of a 15-meter dipole magnets of the Large Hadron Collider. The yellow dotted line shows the location of poor electrical contact, causing the accident on September 19. Image from the report Jorg Vennigera
A review paper by Jörg Vennigera, delivered on November 25 at a meeting of the technical collaboration of ATLAS, provides a detailed analysis of the damage to the LHC and describe future plans. It is decided that the dipole magnet in sector 1-2, which also showed a defective electrical contact to be replaced. But still not decided whether to put the valves for discharging a high pressure in the event of an accident, each cryostat. If you need such a modification, the work with beams will be delayed until 2010.
At CERN is now in full swing preparing for the repair sector 3-4 of the Large Hadron Collider, the victim of a serious accident on September 19. At the recently held 96th meeting of the Commission on experiments at the LHC project leader Lyn Evans (Lyn Evans) presented a report on the results of investigation of the incident and the steps taken. He said that currently repairing the damaged magnets involved about 100 people (see details in the presentation of LHC Status report, PDF, 1,2 MB). It has also recently been announced, and the estimated cost of repair work — about 10 million euros, see, for example, the news LHC repairs underway.
However, researchers are now more worried about is not the cost, and the timing of the completion of repair work. The fact that, besides directly magnets repair itself is also required to develop and introduce a system of security measures to prevent such accidents in the future. And here is where the situation remains uncertain. Nov. 25, at one of the technical meetings collaboration ATLAS, sounded overview report Jorg Vennigera (Jorg Wenniger) News from the LHC (PDF, 5 MB). It provides a detailed analysis of the damage and describe future plans. Among other things, the report should note two things.
First, measurements confirmed that in the sector of 1-2 also have a defective electrical contact resistance of about 100 nano, which in principle could lead to an accident. It is decided that the dipole magnet, which showed that the defect will be replaced.
Secondly, there is still no decision about whether to put the valves for discharging a high pressure in the event of an accident, each cryostat. On the one hand, it minimizes the effects of an accident (because of poorly triggered valves high pressure led to serious mechanical damage to the accelerator). But on the other hand, it will be a very long process, because in this case it is necessary to warm up to room temperature, the entire accelerator LHC, and then work with beams will be delayed until 2010. If such modifications are required, there is a chance that the LHC will work again in the summer of 2009.
It is expected that a final decision will be made in February 2009.