The LHC forward collaboration proposes to build two small calorimeters near the ATLAS detector for high-energy cosmic ray research.
The Large Hadron Collider
After six and a half years of work, CERN leaders and dignitaries celebrate the completion of a second detector cavern. The CMS cavern is 53 x 27 x 24 metres. To make space for the enormous detector, 250,000 cubic metres of soil have been removed from the detector cavern and a second space that houses technical components.
The last superconducting magnet is lowered down an access shaft to the LHC. The 15-metre dipoles, each weighing 35 tonnes, are the most complex components of the machine. In total, 1232 dipoles were lowered to 50 metres below the surface via a special oval shaft. They were then taken through a transfer tunnel to their final destination in the LHC tunnel, carried by a specially designed vehicle travelling at 3 kilometres per hour.
A component known as a small wheel is the last large piece of the ATLAS detector to be lowered into the cavern. The ATLAS detector has the largest volume of any detector ever constructed.
The pixel detector barrel is the last large piece of the CMS detector to be lowered into the cavern.
At 10.28am on 10 September 2008 a beam of protons is successfully steered around the 27-kilometre Large Hadron Collider (LHC) for the first time. The machine is ready to embark on a new era of discovery at the high-energy frontier.
LHC experiments address questions such as what gives matter its mass, what the invisible 96% of the universe is made of, why nature prefers matter to antimatter and how matter evolved from the first instants of the universe’s existence.
Explore the resources prepared for press.
On 19 September 2008, during powering tests of the main dipole circuit in Sector 3-4 of the LHC, a fault occurs in the electrical bus connection in the region between a dipole and a quadrupole, resulting in mechanical damage and release of helium from the magnet cold mass into the tunnel. Proper safety procedures are in force, the safety systems perform as expected, and no-one is put at risk.
More about the incident:
A full technical analysis of the incident is available here.
Or read an analysis of the LHC incident on CERN's press office website.
In line with Japanese tradition, this Daruma doll was painted with one eye to mark the start of the LHC project. The Japanese Vice Minister of Education, Culture, Sports, Science and Technology T. Yamauchi adds the second eye to mark the completion of the project.
The 53rd and final replacement magnet for the Large Hadron Collider (LHC) is lowered into the accelerator tunnel, marking the end of repair work above ground following the incident in September the year before that brought LHC operations to a halt.
The final magnet, a quadrupole designed to focus the beam, is lowered in the afternoon and starts its journey to Sector 3-4, the scene of the September incident. In total 53 magnets were removed from Sector 3-4 after the incident. Sixteen that sustained minimal damage were refurbished and put back into the tunnel. The remaining 37 were replaced and will be refurbished to provide spares for the future.
From a CERN press release, dated 20 November 2009:
Particle beams are once again circulating in the world’s most powerful particle accelerator, CERN’s Large Hadron Collider (LHC). This news comes after the machine was handed over for operation on Wednesday morning. A clockwise circulating beam was established at ten o'clock this evening. This is an important milestone on the road towards first physics at the LHC, expected in 2010.
“It’s great to see beam circulating in the LHC again,” said CERN Director General Rolf Heuer. “We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way.”
The LHC circulated its first beams on 10 September 2008, but suffered a serious malfunction nine days later. A failure in an electrical connection led to serious damage, and CERN has spent over a year repairing and consolidating the machine to ensure that such an incident cannot happen again.
“The LHC is a far better understood machine than it was a year ago,” said CERN’s Director for Accelerators, Steve Myers. “We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.”
Recommissioning the LHC began in the summer, and successive milestones have regularly been passed since then. The LHC reached its operating temperature of 1.9 Kelvin, or about -271 Celsius, on 8 October. Particles were injected on 23 October, but not circulated. A beam was steered through three octants of the machine on 7 November, and circulating beams have now been re-established. The next important milestone will be low-energy collisions, expected in about a week from now. These will give the experimental collaborations their first collision data, enabling important calibration work to be carried out. This is significant, since up to now, all the data they have recorded comes from cosmic rays. Ramping the beams to high energy will follow in preparation for collisions at 7 TeV (3.5 TeV per beam) next year.
Particle physics is a global endeavour, and CERN has received support from around the world in getting the LHC up and running again.
“It’s been a herculean effort to get to where we are today,” said Myers. “I’d like to thank all those who have taken part, from CERN and from our partner institutions around the world.”