@UCSD: An Alumni Publication

An Alumni Publication   Archive vol1no3 Contact
 
Up Front: Letters to and from the editor
Shelf Life: Books
Cliff Notes: Student life and sports
Class Notes: Alumni profiles
Giving
Looking Back: Thoughts on UCSD
Credits: Staff and Contributors
Features
Looking for the God Particle
Time Capsule: 1960-2010
Student Central
The Cell
LOST
Campus Currents
Memories are Made of This
Robot Underwear
Scripps Ship Comes In
Here Comes the Sun
Sniffing Out Trouble
I Wanna Be In Pictures
Rug-Rat Race
Lunokhod Phone Home
Dancing with the Stars
Scripps Goes Google
More
Archive
 

Features May 2007: Volume 4, Number 2

Looking for the God Particle
By Kim McDonald

More than two dozen UC San Diego physicists have begun a search for a hypothetical subatomic particle below the Swiss-French border. If found, they hope that it will allow them to tie the fundamental forces and particles of nature into one grand theory.

Physics Professor Vivek Sharma will give a public talk this winter at UCSD on “What Gives Particles Mass? Searching for the Higgs.” For the latest information on his talk go here.

 

They are among the hundreds of physicists who collide beams of protons, moving in opposite directions at close to the speed of light, with an energy greater than has ever been produced before on Earth.

From the millions of subatomic particle collisions in a newly constructed collider at CERN, known as the Large Hadron Collider, or LHC, near Geneva, the scientists hope to generate tiny fireballs of pure energy from which new particles never before seen on Earth emerge. That should provide them with clues to improve on and go beyond their basic theory of nature—what they call the Standard Model.

“It’s taken us 25 years to build,” Vivek Sharma, a physics professor at UCSD now working at CERN, said of the LHC in interviews that appeared in newspapers, magazines and broadcasts worldwide (see video), since it was restarted in late 2009. “This is what it’s for. Finally the baby is delivered. Now it has to grow.”

The LHC is the world’s largest scientific experiment, involving an estimated 10,000 individuals from 60 countries, including more than 1,700 scientists and engineers from 95 U.S. universities and laboratories. It will attempt to reproduce, on a miniature scale, some of the same conditions that occurred during the first fractions of a second after the Big Bang, when our universe is thought to have come into being some 14 billion years ago.

The main object or particle of the LHC’s search is the Higgs boson, hypothesized by physicists to have been created in the Big Bang’s fireball and to imbue particles with mass. It has never been detected by any of the world’s previously built colliders. And it is thought to exist at energy levels that only the LHC can reach.

“Finding the Higgs Boson will be a marathon challenge, not an easy sprint,” said Sharma, who will be living at CERN during the next few years to direct and coordinate the Higgs boson search for several hundred physicists at more than 38 countries and 183 institutes worldwide. “But we have set the traps with considerable thought and are confident that we will find it in the not too distant future. The thrill of the chase is overwhelming and it will energize us through the course leading to its discovery.”

Sharma and 27 other UCSD physicists and technicians have been shuttling between La Jolla and CERN during their sabbaticals and teaching breaks, for more than a decade now, to make sure that when the LHC is properly operating, data can be collected from one of the European collider’s two big particle detectors—the Compact Muon Solenoid, or CMS.

“The CMS detector is 21 meters long, 16 meters in diameter and weighs around the same as 30 jumbo jets or 2,500 African elephants,” said Sharma “And though it is the size of a small cathedral, it contains detectors more precise than Swiss watches.”

Because of the huge volume of data expected from this experiment, the UCSD team has designed and built the largest data acquisition system in the world to analyze the more than 100,000 collisions per second that will be generated when beams of protons circulating at nearly the speed of light in opposite directions around the 27-kilometer LHC ring are brought together in violent collisions.

“When the two proton beams collide, they will generate, within a tiny volume, temperatures a billion times hotter than in the heart of our Sun,” said Sharma.

Sharma said the detector itself is capable of operating like a 100 megapixel digital camera taking 40 million photos a second. And the 15 million Gigabytes of data expected to be generated each year by the CMS experiment will produce the equivalent of 20 million CDs of data that will require the computing power of about 100,000 of the fastest PC computers.

“This is a seriously big electronics experiment,” said UCSD physics professor James Branson, who joined the project in 1994, when the U.S. abandoned construction of the Superconducting Supercollider (SSC), a bigger version of the LHC, in Texas.

The cancellation of the SSC was a personal blow to Branson and hundreds of other U.S. physicists who had hoped the Texas collider would maintain the U.S. leadership in high-energy physics—not to mention a shorter commute from their university campuses. However, the completion of the LHC has now brought the world’s physicists together for a common goal and reignited the excitement in their field.

“It’s been 20 years since we last made that kind of leap in our field,” said UCSD physics professor Frank Wuerthwein, who was a graduate student when the U.S. abandoned the Supercollider. “There was a sense of disappointment then. But this is now our machine. This is for my generation of physicists.”

“For me, it’s only an inconvenience to have the collider in Geneva instead of the U.S.,” said Branson. “This is one of the places where we’re going to find out about the great laws of physics. At the LHC, we will discover what the basic laws of nature are.”

Branson noted that much of the data from the CMS experiment will be analyzed by newly installed computers in Mayer Hall. “In the past, we’ve had to do the data analysis at the laboratory,” he said. “But we now have a computing center that has lots of power.”

Does that mean it’s possible that the first sighting of the Higgs boson—the Holy Grail of physics or what some have termed the “God particle”—could occur at UCSD? Possibly, although Branson said months or even years of statistical sampling from millions of proton collisions will be required before anyone could claim to have found the Higgs.

“Finding one Higgs particle will re­­quire carefully sifting through much more than 10,000,000,000,000 proton-on-proton collisions,” said Sharma.

Despite the long odds, physicists are glad to be on track. In late March, after a year and a half delay to fix problems with the LHC, the collider  finally started to collide protons at a rapid-fire rate, some 60 times a second. Sharma said he and the other UCSD scientists present for the occasion at CERN felt a sense of relief and exhilaration for the discoveries that are sure to come in the near future.

“My heart stopped when the first event was splashed on the screen,” he said. “The joy of watching CMS quickly and seamlessly take in all the LHC collisions and produce beautifully reconstructed events of proton-on-proton collisions is hard to communicate. LHC and CMS worked in tandem, like a dream machine.”

Kim McDonald is director of science communications at UC San Diego