Cutting Edge

A silicon detector being installed in the Large Hadron Collider in December 2007.

(Credit: Michael Hoch/CERN)

The world's biggest particle accelerator, the Large Hadron Collider, is in full operation after a year of repairs.

The European Organization for Nuclear Research, CERN, said in a statement on Friday that particle beams are once again circulating in the LHC, and that a clockwise circulating beam was established at 10 p.m. in Geneva.

According to the CERN Twitter feed, an anticlockwise beam was also successfully injected, and both beams have completed many thousands of turns of the LHC.

Read more of "Large Hadron Collider up and running again" at ZDNet UK.

The world's largest particle accelerator is on course for a November restart. Six out of eight superconducting sectors are down to working cryogenic temperatures, according to CERN, the European Organization for Nuclear Research.

James Gillies, head of communications for CERN, told ZDNet UK on Monday that the Large Hadron Collider (LHC) would probably be ready to collide beams of particles by mid-November.

"Things are going well," said Gillies. "We hesitate to say 'hurray' just yet, but things are going smoothly."

Gillies said CERN plans to restart the giant experiment in incremental stages.

Read more of "LHC on course for November restart" at ZDNet UK.

The latest delays to the restart of the Large Hadron Collider are likely to have been caused by a faulty hose, according to CERN, the European Organization for Nuclear Research.

Liquid helium leaks in the world's largest particle accelerator were probably caused by a problem with a flexible hose in the liquid helium transport circuits, the organization said an article in its official bulletin, published on Friday.

Click image for gallery on the Large Hadron Collider.

(Credit: Maximilien Brice for CERN)

The hose vented helium into the vacuum insulation of the Large Hadron Collider (LHC), CERN officials suspect.

CERN has revised the restart date of the LHC several times since the experiment was put out of action in September by an electrical fault. According to the latest estimates, the particle acceleration experiment is unlikely to restart before mid-November.

The vacuum leaks occurred in sectors 8-1 and 2-3 in July. At the time, CERN said that the sectors would have to be warmed from 80 Kelvin (-315.67 degrees Fahrenheit) to room temperature to effect repairs.

On Monday, the organization changed that plan, saying the vacuum subsectors at the end of the sectors will be warmed to room temperature to locate the leaks and repair them. The rest of those sectors will "float" in temperature from 80K.

Both leaks happened at the place where the final magnet of those sectors, which is known as Q7, joins the electrical feedbox, known as the DFBA.

The LHC experiment is designed to enable research into fundamental questions about nuclear particles, such as the existence of dark matter.

Tom Espiner of ZDNet UK reported from London.

The restart of the Large Hadron Collider has been pushed back even further, following the discovery of vacuum leaks in two sectors of the experiment.

The world's largest particle collider is now unlikely to restart before mid-November, according to CERN, the European Organization for Nuclear Research.

The project had been expected to start again in October.

The collider's experiments are designed to answer fundamental questions about the nature of matter.

(Credit: CERN)

To repair the leaks, which are from the helium circuit into the insulating vacuum, sectors 8-1 and 2-3 will have to be warmed from 80K to room temperature. Adjacent sub-sectors will act as "floats," while the remainder of the surrounding sectors will be kept at 80K, CERN said in a statement. The repair work will not have an impact on the vacuum in the beam pipe.

The LHC experiment, which is designed to answer fundamental questions about the nature of matter, had to be halted nine days after it became fully operational last September, due to a leak of liquid helium. To be super-conductive, the experiment is cooled using liquid helium.

CERN has pushed back the restart a number of times, as repair work has continued. To begin with, scientists said the LHC experiment would restart in April 2009.

In May, CERN told ZDNet UK that the restarted experiment could run through the winter to make up some of the lost time. Normally, running the experiments through the alpine winter is prohibitively expensive, due to high electricity costs. However, as the experiment has not been running since last September, CERN would have the budget to cover energy costs over the winter.

Tom Espiner of ZDNet UK reported from London.

The grid that will process data from the Large Hadron Collider has undergone stress-testing, as CERN and other groups try to gauge its limits.

The tests, called Scale Testing for the Experiment Program '09, threw huge amounts of data around the distributed computing project, which uses dedicated optical-fiber networks to distribute data from CERN (European Organization for Nuclear Research) to 11 main computer centers in Europe, Asia, and North America.

From these centers, data is dispatched to over 140 centers in 33 countries around the globe, where the LHC data is managed and processed. The recent grid tests, which lasted for two weeks, were completed before the beginning of July.

Click image for gallery on the Large Hadron Collider.

(Credit: Maximilien Brice for CERN)

LHC computing-grid project leader Ian Bird said Friday that CERN had tried to break the grid but had not succeeded.

"People were trying to break the system by seeing how much data we could push through it, but we didn't (break it)," Bird told ZDNet UK. "The test was successful."

Data from all the experiments running at CERN--including analyses from the Atlas particle accelerator, which is linked to the LHC--were processed through the grid, according to Bird. While the amount of data expected from the LHC will be in the area of 1.3GB per second, the grid systems were bombarded with 4GB per second. "The data volume got to a much larger scale than is needed," Bird said.

CERN plans to restart the LHC in October, following an incident last September that halted the experiment. A fault, caused by imperfect welding, led to a leak of liquid helium that caused damage when it heated and expanded.

At present, the LHC itself is not generating any data, as no experiments are being conducted, Bird said. However, the experiment was gathering data from cosmic rays hitting the experiment until testing of the machine stopped the collection. This data is due to be collected again "in a few weeks," Bird added.

Bird did not rule out a further major test of the computing grid before the LHC's October restart, as some parts of the grid had been offline during the testing due to scheduled downtime.

Tom Espiner of ZDNet UK reported from London.

The flagship particle accelerator at the European Organisation for Nuclear Research is to be restarted in October, as opposed to September.

Click image for gallery on the Large Hadron Collider.

(Credit: Maximilien Brice for CERN)

The Large Hadron Collider has been offline since an incident on September 19, when an equipment failure caused extensive damage. James Gillies, CERN's head of communications, said on Monday that an internal schedule set in February to restart the experiment has been pushed back by two or three weeks, but that the restart would still commence in the fall.

"The situation is a retreat from February," Gillies told ZDNet UK. "We had aimed for the end of September, but we're now looking at somewhere in October."

CERN has revised its LHC restart date a number of times. An original October 2008 estimate of an April 2009 restart was pushed back to the end of the summer, and was then revised to September.

The experiment, which is designed to improve scientific understanding of the nature of matter, had to be halted nine days after it was fully powered up, after an electrical malfunction caused a leak of liquid helium.

In May, details emerged that the malfunction had been caused by a faulty splice between two of the busbars that carry the superconducting cable in the LHC. Gillies said that the problem had not been in the design, but rather in the implementation of the electrical circuits for the quench system.

"It was a quality control flaw," Gillies said. "Most of the splices were done well, but a few of the solder joints were not perfectly carried out. We know there were a number of faulty splices in the machine. We've repaired a few, and we'll be repairing more."

CERN has developed noninvasive ways of testing the electrical circuits in some of the systems, which have remained cooled to 80 Kelvin (negative 315.67 degrees Fahrenheit), Gillies said. In circuits where faults have been found, Gillies said the surrounding sectors will be warmed to room temperature, and then the circuits will be repaired and tested again.

Gillies said CERN won't be able to give an exact restart date until August, when testing is completed. CERN has not decided whether to run the experiment at 4 teraelecton volts or at 5TeV. The world's most powerful particle accelerator, the Tevatron at Fermilab near Chicago, runs at 1TeV.

Tom Espiner of ZDNet UK reported from London.

The Large Hadron Collider, currently undergoing repairs, will change its schedule and run through the winter to make sure the experiment provides workable results.

The European Centre for Nuclear Research (CERN) flagship particle accelerator has been out of action since September, when an electrical fault called a halt to an experiment to understand the fundamental physics of matter. It is scheduled to restart in September 2009.

Click image for gallery on the Large Hadron Collider.

(Credit: Maximilien Brice for CERN)

On Wednesday, James Gillies, head of communications at CERN, said the LHC could carry on running over the subsequent months. Normally, CERN particle-acceleration operations cease in November for the winter, because energy costs throughout the winter months are prohibitively high.

"The schedule is fairly tight," Gillies told ZDNet UK. "Instead of shutting down for the winter, this year, we will start up in September, October, or later, and run continually until we have enough data in the can. We will run straight through the winter if necessary."

CERN is able to cover the energy cost of running the LHC during outside its schedule because it had had less expenditure while the experiment was halted, Gilles said. "We're getting the money from the standard CERN budget," he said. "If we hadn't had the incident last year, we would be running the LHC."

Gillies added that CERN would continue to be supplied by EDF on the French side and EOS on the Swiss side, and that EOS would provide energy through the cold season.

The energy demands of the LHC are high. The particle beams are designed to run at a maximum of 7 TeV, and have run at around 5 TeV. There is 350MJ stored in each beam, which CERN scientists estimate has enough energy to drill a 30m hole in copper.

The LHC experiment, designed to smash beams of nuclear particles into each other, was brought to a halt nine days after it was started. A fault in a copper bus-bar caused a resistive zone, which then prevented the normal operation of a quench. This caused an electrical arc, which punctured the cavity containing liquid helium used to supercool both the experiment and the magnets which direct and focus the particle beams.

The fault was the result of an insufficiently welded joint between two of the bus-bars, which are used to carry the superconducting cable. CERN beams department scientist Jorg Wenninger said in a presentation (PDF) on Monday that all the approximately 1,700 joints had been inspected. Many were found to have bad soldering or reduced electrical contact, the same problem that caused the initial incident.

A new quench-monitoring and protection system has been implemented that will give an early warning if any part of the superconducting coils or bus-bars develops high resistance, Gilles noted. He also said that more helium safety valves with a higher capacity were being installed.

Tom Espiner of ZDNet UK reported from London.

The final replacement magnet for the Large Hadron Collider has been lowered into the giant particle accelerator's tunnel.

The European Organization for Nuclear Research (CERN) announced on Thursday the completion of the LHC's above-ground repair work. Work is still going on below ground to connect the 53 reinstalled magnets, which are used in the scientific project to guide particles around a 17-mile tunnel under the Alps. The LHC fires two high-speed particles streams around the tunnel in opposite directions, smashing them together at certain points in order to learn more about scientific mysteries such as the nature of matter.

This photo from last year shows two of the most severely broken interconnects, which were between the magnets in LHC sectors three and four.

(Credit: CERN)

The LHC went offline in September 2008--just days after the LHC was turned on for the first time.

The problem started when a faulty electrical connection between two of its magnets caused a malfunction in the cooling system that keeps the machine below -271 degrees C. That malfunction subsequently led to a liquid helium leak, resulting in a need for widespread repairs. By CERN's latest reckoning, the system will be turned on again in late September of this year.

"This is an important milestone in the repair process," Steve Myers, CERN's director for accelerators and technology, said in a statement. "It gets us close to where we were before the incident, and allows us to concentrate our efforts on installing the systems that will ensure a similar incident won't happen again."

The magnet that was lowered underground on Thursday was a quadrupole: one of the magnets that focuses the particle stream, rather than one of the dipole magnets that keep the stream on course.

Click image for a 2008 gallery on the LHC.

(Credit: Maximilien Brice for CERN)

Of the 53 magnets that were affected by the malfunction, 16 were refurbished and put back into the tunnel, while 37 were replaced by spares. The replaced magnets will themselves be refurbished to provide spares for the future.

Apart from the repair itself, the LHC is also gaining systems to monitor its functioning, in order to avoid a repeat of the September incident. Extra pressure valves are also being installed to make any helium releases less disastrous to the project.

David Meyer of ZDNet UK reported from London.

The Large Hadron Collider will come back online in late summer 2009 at the earliest, and not in June as previously expected.

The LHC was shut down in September, nine days after it was first fully powered up, following a helium leak caused by an electrical fault. The world's most powerful particle accelerator is designed to smash beams of protons into each other, test fundamental physics theories, and help understand the nature of matter.

The machine is located at the European Center for Nuclear Research (CERN), where it straddles the Swiss-French border.

CERN director Robert Aymar said in October that the LHC would come back online at the beginning of April 2009, following CERN's annual maintenance period. Earlier this month, that date was revised to June 2009.

However, the plan now is to restart the experiment in late summer next year, CERN's head of communications, James Gillies, told ZDNet UK on Friday.

The accelerator operations group at CERN came up with two possible plans to restart the LHC, details of which are included in a CERN presentation. According to the document, written by Jorg Weninger, a member of the operations group, "Plan A" called for a restart of the experiment in late summer 2009, with the beam energy and intensity limited to minimize the risk of another accident. "Plan B" delayed switching on the beam until there had been a complete upgrade to the pressure-relief system, which would mean the LHC would be restarted in 2010 at the earliest.

Gillies confirmed Plan A rather than Plan B will now be implemented. "The priority is to get collision data from the experiment," said Gillies. "The LHC will run next year."

The liquid helium leak in September caused damage to the LHC, mainly as a result of the helium expanding as it warmed. Under Plan B, CERN would have installed pressure-release valves on each of the super-conducting magnets' cryostats. To do that, it would have had to warm the whole 17 miles of the LHC ring.

Each of the eight sectors of the LHC are independently cooled, Gillies said, and at the moment three of the sectors are warm. The plan is to modify these sectors, which will include fitting pressure-release valves to the cryostats on the dipole magnets, to try to prevent damage in the event of another accident. The remaining five sectors will be kept cool, and they will have pressure-release valves fitted as and when other repairs or modifications are needed.

The beam energy of the LHC is designed to eventually be 7 tera electron-volts (TeV), said Gillies, who added that CERN was hoping the experiment would run at approximately 5 TeV next year.

"The five undamaged sections can run at 5 TeV, and the rest of the machine can run at 4 TeV." said Gillies. "The highest we're hoping to run next year will be lower than 7 TeV."

Tom Espiner of ZDNet UK reported from London.