Inside a 27-kilometer tunnel below the surface of France and Switzerland, the world’s largest particle supercollider is beginning to rise out of dormancy to begin running fundamental physics experiments once again.
The Large Hadron Collider is expected to restart collisions in mid-November, according to Michael Witherell, professor of physics and vice chancellor of research for UCSB.
The collider began to run experiments in September 2008 but was shut down nine days later by a liquid helium leak caused by a fault in the electrical connection between two of the machine’s magnets. After a year of extensive repairs, the collider is almost ready once again for research. As of today, the facility has been cooled to 1.9 degrees Kelvin — colder than outer space — and the particles have since once again been injected into the collider and circulated partially, indicating that the LHC is coming closer to full operation in the next few weeks.
The Muon, the Machine, the Mission
According to CERN, the European Organization for Nuclear Research, the Large Hadron Collider was built as a tool to further research on dark matter, dark energy, additional dimensions, the Higgs boson and supersymmetry. The facility was built to achieve a beam with an energy of 7 tera electron volts, or TeV, and to reach 14 TeV by colliding two particle beams at 7 TeV together. At this level of energy, according to Joe Incandela, a physics professor at UCSB who is currently stationed at CERN, there is a new frontier of scientific knowledge to discover.
“We are hoping in 2010 to get to higher energy levels, such as 7 TeV,” Incandela said. “That will be new territory. We may see some new physics, evidence of whole new dimensions … a whole new spectrum of particles, supersymmetry. … There is a lot of new territory to mark out.”
The most popular study is the search for the Higgs boson, a particle which gives objects mass. The Higgs, if found, is expected to tie together the weak and electromagnetic forces in physics, shortening the number of fundamental forces and moving scientists toward a Grand Unified Theory. Incandela said it may be quite a while before CERN may — or may not — find the boson.
“We are looking for the Higgs; we know it’s there somewhere, but we don’t know its mass. We know all the ways it can decay; it’s very rare to produce. … [The Higgs is] hard to distinguish from other beings, others produce a signature similar to the Higgs,” Incandela said. “We don’t expect to see anything about the Higgs for a few years.”
Data collected from the experiments will also go toward a better understanding of supersymmetry, a very interesting theory for physicists because it may provide more information on dark matter and energy, which together make up 96 percent of the universe, but have remained an enigma, according to CERN.
The LHC itself is a great feat of science and engineering, and its creation alone should count as a triumph, according to Incandela.
“I am very impressed with the accelerator, it sends a beam of protons, … [the magnets] accelerate the beam, every time it goes around, it gets a kick from the magnets, and all the magnets have to change 50 times a second [to accommodate the beam],” Incandela said. “If you really understand everything involved, you’re surprised it even works at all.”
While there is no immediate application of the LHC research, Incandela said the study can have great uses in the future.
“These things, of course, will not have an impact on your daily life for some time,” Incandela said. “What we do is pure physics; if there was an application it would be called applied physics.”
UCSB: University (that helped make the) Compact (Muon) Solenoid (to search for) Bosons
UC Santa Barbara has contributed a great deal to the project by being part of the Compact Muon Solenoid project. The CMS is a machine able to detect the various particles produced within an LHC collision. According to Incandela, the detector is able to pick up particles moving at almost the speed of light.
“The Compact Muon Solenoid, this experiment that UCSB is on, has roughly 80 million channels of electronics,” Incandela said. “Those 80 million channels have to register collisions between beams that may be as little as 20 nanoseconds apart. When the particles are moving at near the speed of light, they can move 25 feet [within that time]. Our detector is bigger than 25 feet, so we have particles inside the detector at any one time that can be from more than on such beam-beam collision.”
Incandela said the CMS, which is structured in layers that each provide data on certain particles that are generated by the collision, is a highly complicated machine that will require a large amount of calibration to provide data, and is critical to the studies being done at the LHC.
“The CMS [contains] particles from multiple collisions, [so] it needs to be highly synchronized,” Incandela said. “It’s a combination of science and art; it really takes a kind of artist to get the most out of these things.”
The CMS, which will spend a large amount of time calibrating due to the necessary preciseness of the measurements, will begin to produce data before 2010 and will generate a massive amount of data over the summer, Incandela said.
“By summer, we expect to collect one million collisions per hour, each will produce 350kb of data in a compressed form,” Incandela said. “To even handle that amount of data flow, we have around 200,000 core computers to analyze the data. … Just understanding the detector [will take some time].”
Can’t Collide Without Controversy
The LHC project has not been without criticism. In the early days of the project and some time before the initial experiments in September 2008, there were protests claiming that the LHC’s ability to produce miniature black holes would end the world. However, these concerns were found by CERN to be unfounded, according to Incandela. Since the LHC will not produce higher-energy collisions than naturally occurring cosmic rays, which have been observed to not produce significant black holes, Incandela said he feels that the experiments are safe.
“The beams we produce are much less than cosmic rays,” Incandela said. “We feel pretty confident [that the LHC is safe].”
Most recently, however, an Algerian physicist working at the LHC was found to have ties to terrorist groups, causing worry that the LHC might be a target of or a tool for terrorism. CERN released a statement that said the suspect, who was not a CERN employee, was targeting France in general, rather than the LHC and did not have access to critical systems.
“CERN … has particularly strict access protocols for areas deemed sensitive for personal or operational safety,” the press release said. “The person arrested … did not have access to any such areas.”
Incandela said the LHC, while using significantly high-energy beams, cannot cause more damage than a stick of dynamite.
LHC Is Not Just a Supercollider, It Is a State of Mind
According to Incandela, the LHC is beyond a science project; it is a social experiment.
“The LHC is a result of collaboration by people all over the planet. We have built these devices with microscopic precision even while having people [working on the project] all over the world.”
Incandela said. “People can get along if they have the right attitude. We have people here from Iran, Taiwan and China. … Scientists get along, and that gives me the hope that people [in general] can get along.”