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Super-collider enabled by EEs
R. Colin Johnson
EE Times
(09/08/2008 10:18 PM EDT)
PORTLAND, Ore.—The world's most powerful particle accelerator, the Large Hadron Collider (LHC), will attempt to form its first particle beam on Wednesday, Sept. 10th, enabled by EEs who designed its superconducting magnets, detectors and worldwide grid computing network.
The LHC was constructed at the CERN (Conseil Europeen pour la Recherche Nucleaire or European Council for Nuclear Research, Geneva).
View a live webcast of the event at 4 a.m. Eastern Time Sept. 10, 2008 athttp://webcast.cern.ch/
The LHC consists of a 16-mile long ring of superconducting magnets--1232 dipole magnets each 49 feet long which are used to bend the beams, and 392 quadrupole magnets, each 16-to-22 feet long, to focus the particle beams--cooled with 60 tons of liquid helium to -456 degree Fahrenheit.
Trillions of protons accelerate around the ring 11,245 times a second to achieve 99.99 percent the speed of light, resulting in 600 million collisions per second. Two beams of protons traveling opposite directions will each achieve an energy of 7 TeV (tera-electronvolts), resulting to head-to-head collisions of 14 TeV--seven times greater than the most power accelerator today at the Fermi National Accelerator Laboratory (Batavia, Ill.)
Many experiments will be performed by the LHC that plumb the mysteries of the universe by recreating the conditions of the Big Bang--producing subatomic particles that have not been seen since the beginning of time itself. Mysteries that the LHC will hopefully resolve include the origin of matter and mass, the existence of extra dimensions, and the whereabouts of dark matter and dark energy, which are estimated to compose 96 percent of the universe, but which are invisible to physics today. The LHC will also attempt to create microscopic black holes--an experiment that doomsayers predict will swallow the Earth, but which scientists at CERN say are created naturally all the time when cosmic rays his the atmosphere, but which can now be studied by detectors in the LHC.
Throughout the construction of the detectors installed there in the LHC, electrical engineers have been instrumental to its success, according to University of Nebraska at Lincolm professor Ken Bloom.
"EEs have helped us design a general purpose detector that could capture whatever the new physics could be," said Bloom. "And there is electrical engineering through out the whole experiment--from its ultra-low noise amplifiers to its realtime computing systems."
One of the most important experiments to be performed by the LHC depends on the Compact Muon Solenoid (CMS) detector which is built around a huge solenoid magnet wtih a 12,500 ton yoke and using a cylindrical coil of superconducting cable that generates a magnetic field of 4 teslas--100,000 times that of the Earth's magnetic field.
"The CMS experiment is one of the two big general purpose experiments at the CERN Large Hadron Collider," said Bloom. "Our goal is to discover and explore new physical phenomena that we expect to observe in these high-energy particle collisions. There may even be extra dimensions of space besides the three that we are used to."
According to Bloom, who is the project manager for tier-two grid computing in the U.S., grid computing was the only option available to the engineers making the CMS at the LHC a reality.
"Just the raw data coming off the detector will be petabytes per year, for which we have had to reinvent grid computing to handle," said Bloom. "There will be millions of collisions per second, yet we can only process that data at about 100 Hz, which means the EEs had to design a high-speed online system that was smart enough to record only the collisions of interest. Even so, it was not possible to get enough power and computing into a single data center to handle these massive data sets, so we have gone to a distributed model that is enabled by the fact that we have high-speed networks to move the data around the world."
The six experiments at the LHC, including the CMS, will produce about 15 petabytes of data per year, which will be recorded and stored at CERN, but will be analyzed by a worldwide grid computing network made accessible to over 5,000 scientists around the globe.
The Worldwide LHC Computing Grid is facilitated by the the Open Science Grid, which has more than 60 sites in the US and five sites in Brazil, Taiwan and England. The Worldwide LHC Computing Grid consists of seven tier-one data centers (including Fermi National Accelerator Laboratory and Brookhaven National Laboratory) which will partition the data sets into groups appropriate for the six experiments to be performed by LHC scientists. Finally, 40 tier-two data centers (including seven in the U.S.) will allow scientists to apply analytic algorithms to the data sets appropriate to their particular experiments. The U.S. data centers will provide more than 10 petabytes of disk cache for simulation and analysis.
The tier-one data centers are all connected by 10-Gbit per second fiber optic links which will be utilized around the clock to stream and partition the data into appropritate sets. The tier-two data centers in the U.S. will make use of the Energy Sciences Network (ESnet) and the Internet2.
U.S. funding was provided by the National Science Foundation and the US Department of Energy Office of Science.
