Three hundred feet below the ground in a tunnel that crosses between France and Switzerland, scientists are gearing up for the greatest physics experiment ever performed. The purpose? Nothing less than to discover the origins of the universe.
The experiment involves smashing subatomic particles together, in an effort to simulate the Big Bang — the model of the universe that says the universe came about through a huge explosion and has been expanding ever since.
Seventeen miles of underground tunnel have been modified to accommodate the Large Hadron Collider, the world’s largest particle accelerator. At one of the several intersection points along the way will be the portion that more than 40 faculty members, graduate students, postdoctoral researchers, engineers, technicians and undergraduates from UCSB have helped put together for eight years: the Compact Muon Solenoid.
The CMS is a particle detector aimed at what the scientists hope will be one of several collision sites.
“When two protons collide with a lot of energy, new particles are produced,” said Claudio Campagnari, one of the researchers in the UCSB group. “In other words, the energy of the collision can be used to create particles according to Einstein’s famous equation, E=mc^2.”
The CMS is designed to track and image what particles come out of the collision. It is analogous to an enormous and powerful digital camera, according to David Stuart, another UCSB researcher.
“In fact, the devices use technology (silicon sensors) similar in concept to what is at the heart of a digital camera,” he said. “But, each individual piece is much bigger than a camera’s sensor, and there are thousands of them placed all around the collision point.”
By tracking the path these particles take when bent by the strong magnetic field around them, the scientists can determine what kind of particle they are,
“From the amount of bend, we can measure the velocity of the particles,” Campagnari said.
It’s not the prospect of seeing what the CMS can easily detect that intrigues the scientists who helped put together the CMS. It’s what doesn’t interact with light, and what hasn’t yet been directly observable.
“For example, we know that some of the sub-atomic particles have mass, and indeed those masses have been precisely measured, but we have not yet convincingly explained what generates those masses,” Stuart said. The Higgs boson is an elementary particle that is still a theory, but one that has been widely accepted because of its ability to fill a rather large hole in the science of particle physics.
“You could say that the particles are part of a jigsaw puzzle. When you look at the properties of just some of the particles, you can tell that there are other particles missing,” researcher Jeff Richman said. By re-creating the Big Bang, the LHC will be able to create these so-called “God-particles” that have the ability to give these sub-atomic particles their mass.
If the scientists do find a particle after the billions of collisions per second that the CMS will be imaging, and determine it is indeed the Higgs boson, Scottish physicist Peter Higgs most likely would win the Nobel Prize, Richman said.
The collisions in the LHC are also predicted to create dark matter, matter that physicists believe makes up almost a quarter of the universe but remains invisible. In the closed environment of the particle accelerator, Stuart said, if the LHC does create dark matter, the CMS could show something about it.
It could take years, Richman said, “but we will get lots of data and, if we don’t observe the Higgs particle, we will conclude that either the particle does not exist or that it has properties that are different from what we expect.”
Despite all the time (15 years so far), money (about $10 billion) and even public outcry from people claiming that recreating the Big Bang will create tiny black holes that will gobble up the Earth (refuted by the American Physical Society and the LHC’s parent organization, CERN among others), the scientists remain excited about the prospects the collider offers when it performs its first experiments in a few weeks. The LHC powered up and sent a beam around for the first time last Wednesday.
“The reason that we are so interested in this particle is that it is part of a beautiful explanation that seems to make sense to us, but which is not yet proved,” Richman said. “This may not sound all that important. But mass is such a key property of matter that we really want to understand where it comes from.
“It won’t help anybody build a better mousetrap, but we will know a lot more about how the universe is put together.”
Noozhawk staff writer Sonia Fernandez can be reached at sfernandez@noozhawk.com.