19-06-2009: CERN reports on progress towards LHC restart

25 juni 2009
Geneva, 19 June 2009 - At the 151st session of the CERN* Council today,
CERN Director General Rolf Heuer confirmed that the Large Hadron Collider
(LHC) remains on schedule for a restart this autumn, albeit about 2-3
weeks later than originally foreseen. Following the incident of 19
September 2008 that brought the LHC to a standstill, a great deal of work
has been done to understand the causes of the incident and ensure that a
similar incident cannot happen again.

"Many new tests have been developed," said CERN's Director for
accelerators, Steve Myers. "That's given us a wealth of information about
the LHC splices, and confidence that we will be in good shape for running
this year."

The root cause of the September incident was a faulty splice in the
high-current superconducting cable between two magnets in LHC sector 3-4.
New non-invasive techniques have been developed to investigate the
splices, of which there are some 10 000 around the LHC ring, and determine
whether they are safe for running or whether they need to be repaired. As
part of this process, one more sector of the LHC, sector 4-5, is currently
being warmed up. This will bring increased confidence that the splices are
fully understood.

Sector 4-5 has been measured at a temperature of 80 K, indicating at least
one suspect splice. By warming the sector, the results of this measurement
can be checked at room temperature, thereby confirming the reliability of
testing at 80 K.  If the 80 K measurements are confirmed, any suspect
splices in this sector will be repaired. More importantly, validation of
the 80K measurements will allow the splice resistance in the last three
sectors to be measured at this temperature, thereby avoiding the time
needed for re-warming. The measurements in these sectors will provide the
information needed to determine the start-up date and initial operating
energy of the LHC in the range 4-5 TeV, since running at 4 TeV should be
possible without further repairs, whereas 5 TeV could require extra work
to be done.

A key part of the modifications being made to the LHC is the so-called
quench protection system (QPS), which triggers evacuation of the stored
magnetic energy quickly and safely should a part of the LHC's
superconducting system warm up slightly and cease to be superconducting.
Following the September incident, a new enhanced QPS system was designed
and is presently under construction. The new system will be fully tested
and operational in late summer 2009. This new system will protect the LHC
from incidents similar to that of 19 September 2008.

Work on the new QPS is just one aspect of the work in the LHC tunnel being
carried out by teams from CERN, supported by scientists from other
particle physics laboratories around the world. New pressure relief valves
are being installed, the ultra-high vacuum system is being improved, and
the systems anchoring the LHC magnets to the floor are being strengthened.
All of this contributes to preparing the machine for a long and safe
operational lifetime.

"We've received an unprecedented level of support from physics labs and
institutes around the world through the manpower they've provided to help
us through the repairs and consolidation, as well as the invaluable advice
we've received from the external committees that have studied the measures
we're taking," said Professor Heuer. "It's a sign of the increasingly
global nature of particle physics, and we're extremely grateful for the
solidarity we're seeing."

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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


About CERN
*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.