In addition to the information contained in Seth’s post, there was another interesting LHC update today at the ATLAS Week. Last week, there was a talk that caused a lot of conversation among the physicists that implied the CERN management was considering the possibility of not having any beam at all in the LHC in 2009. During the talk today, the statement was made that there are definitely no plans being considered to not try for collisions in 2009.
The schedule in this talk calls for the machine to be cold at the end of July. Of course, something could go wrong with the repairs, but every effort is being made to have collisions next year. The collision energy next year would be at a maximum of 10 TeV (14 TeV is the design) and possibly lower.
Some other interesting points in the talk:
- Approximately 100 people from CERN (and contractors) are already working on the repairs.
- 39 dipoles & 14 “short straight sections” in the incident area and in the buffer zone around it will be removed and repaired or replaced. About 20 new dipoles will be installed before the end of the year.
- 12 dipoles and 6 SSSs have already been transported to the surface. The first replacement dipole was transported underground on Saturday. Some neat pictures here.
- Techniques have been developed to spot resistive splices, the original cause of the disaster.
- The anchoring of some of the cryostats will be reinforced, so they wouldn’t be able to move in future incidents.
Great links to photos Adam!
I’m really excited for LHC to start up again! Thanks for the update. =)
Bruce Lamar Rosenberg’s thoughts on modifications to protect the LHC from overpressure explosions listed in temporal order of occurence:
BACKGROUND:
The LHC experienced a catastrophic failure caused by overheating of a solder joint that led to a magnet going non-superconducting generating heat producing boiling of the liquid helium coolant leading to an overpressure that ruptured the ring and damaged numerous sections and magnets. The latest information that I read was that the ring tube had one emergency relief valve every 4 sections and that the current valves had insufficient flow to reduce pressure adequately. One fix mentioned is that the valves are being replaced with ones with larger diameters to handle a greater flow of liquid helium.
FIRST IDEA FOR IMPROVEMENT:
Score each of the tubes much in the manner of “pop top” beer cans so small areas of the tube will blow out in case of over pressure. One would want to have say 4 equal sized blow-outs equally spaced around the circumference of the section so as to equalize the forces on the structure of the escaping gas.
SECOND IDEA FOR IMPROVEMENT:
A problem with the first idea is that one or more of the blow-outs might pop before the others producing unequal forces on the structure and damage it thereby. A solution to this would to somehow interconnect the blow-outs so that they had to blow simultaneously. This could be accomplished by placing small explosive charges on each blow-out and simultaneously detonating the charges by an electronic overpressure sensor.
THIRD IDEA FOR IMPROVEMENT:
Modify the “O” rings (if there are any) between the sections such that they fail above a certain pressure (an action causing the Challenger space shuttle disaster).
FOURTH AND BEST IDEA FOR IMPROVEMENT:
Use explosive bolts to connect the sections and when overpressure is detected in one section, simultaneously blow the bolts connecting it to the other sections ahead and behind it allowing relief of excess pressure. However, this would cause massive coolant loss unless each of the sections is independent, coolant-wise, of the others. Presumably there are supporting pedestals under each of the sections to prevent collapse of the detached segment.
These ideas are respectfully submitted to the LHC effort. I am willing to elaborate on this matter.
Bruce Lamar Rosenberg
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Atlantic City, NJ 08401
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