[新聞] LHC to run at 3.5 TeV for early part of 2009-2010 run..
http://www.interactions.org/cms/?pid=1028389
LHC to run at 3.5 TeV for early part of 2009-2010 run rising later
Geneva, 6 August 2009. CERN's[1] Large Hadron Collider will initially run at
an energy of 3.5 TeV per beam when it starts up in November this year. This
news comes after all tests on the machine's high-current electrical
connections were completed last week, indicating that no further repairs are
necessary for safe running.
"We've selected 3.5 TeV to start," said CERN's Director General, Rolf Heuer,
"because it allows the LHC operators to gain experience of running the
machine safely while opening up a new discovery region for the experiments."
Following the incident of 19 September 2008 that brought the LHC to a
standstill, testing has focused on the 10,000 high-current superconducting
electrical connections like the one that led to the fault. These consist of
two parts: the superconductor itself, and a copper stabilizer that carries
the current in case the superconductor warms up and stops superconducting, a
so-called quench. In their normal superconducting state, there is negligible
electrical resistance across these connections, but in a small number of
cases abnormally high resistances have been found in the superconductor.
These have been repaired. However, there remain a number of cases where the
resistance in the copper stabilizer connections is higher than it should be
for running at full energy.
The latest tests looked at the resistance of the copper stabilizer. Many
copper connections showing anomalously high resistance have been repaired
already, and the tests on the final two sectors, which concluded last week,
have revealed no more outliers. This means that no more repairs are necessary
for safe running this year and next.
"The LHC is a much better understood machine than it was a year ago," said
Heuer. "We can look forward with confidence and excitement to a good run
through the winter and into next year."
The procedure for the 2009 start-up will be to inject and capture beams in
each direction, take collision data for a few shifts at the injection energy,
and then commission the ramp to higher energy. The first high-energy data
should be collected a few weeks after the first beam of 2009 is injected. The
LHC will run at 3.5 TeV per beam until a significant data sample has been
collected and the operations team has gained experience in running the
machine. Thereafter, with the benefit of that experience, the energy will be
taken towards 5 TeV per beam. At the end of 2010, the LHC will be run with
lead ions for the first time. After that, the LHC will shut down and work
will begin on moving the machine towards 7 TeV per beam.
[1] CERN, the European Organization for Nuclear Research, is the world's
leading laboratory for particle physics. It has its headquarters in Geneva.
At present, its Member States are Austria, Belgium, Bulgaria, the Czech
Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy,
Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland
and the United Kingdom. India, Israel, Japan, the Russian Federation, the
United States of America, Turkey, the European Commission and UNESCO have
Observer status.
CERN is publishing regular updates on the LHC in its internal Bulletin,
available at http://www.cern.ch/bulletin, as well as via twitter and YouTube
at http://www.twitter.com/cern and http://www.youtube.com/cern.
Media Contact:
Contact : James Gillies, Press Office
Tel. +41 22 767 4101
Cell. : +41 76 487 4555
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08/07 22:52, , 1F
08/07 22:52, 1F