Super Collider and Its Quest: Heart of Matter
The irony of high-energy physics is that it takes bigger and bigger machines to explore tinier and tinier crumbs of matter.
The proposed superconducting super collider would be the biggest accelerator yet, and it would search for the smallest particles that theoretical physicists have so far dared to guess at.
The super collider would do this by colliding protons, tiny particles found in the nucleus of atoms, at extremely high speeds--enough, it is believed, to tear apart tinier particles that cling together fiercely.
The protons would be accelerated with radio waves, which they ride much as surfers ride waves at the beach. This process, however, can take some seconds, during which the protons would travel millions of miles. The double-barrelled oval-shaped collider would essentially serve as an endless race track giving protons time to reach collision speed, which is near the speed of light. The beam in one tube would move clockwise while the other moved counterclockwise.
Protons are like any other solid object: once in motion, they tend to continue in a straight line, as speeding cars resist going around a corner. A magnetic field would be used to keep the protons inside the twin oval-shaped tubes. The 53-mile-long tubes would have relatively easy curves, which helps.
Because the protons would move so fast, very strong superconducting magnets would be needed. These magnets would be made with superconducting wire, which allows the free flow of electricity when refrigerated to extremely low temperatures.
At several points along the ring, the beams would be made to collide head-on in laboratories called collision halls. There, sensitive computers would track the debris produced by the collisions, looking for particles with predetermined characteristics.
Quarks and Leptons
Several existing colliders use this technology, but they are not powerful enough to break off certain elements of the atom. They have been able to reduce atoms to such fundamental particles as quarks and leptons and to classify six types of each.
One type of quark is the building block of protons and neutrons, which make up the nucleus of atoms. One type of lepton is the electron, which high school models show orbiting the nucleus much as planets orbit the sun.
Existing colliders have broken down these particles to discover other particles, called intermediate vector bosons, that act as a sort of subatomic glue holding the whole works together.
Theoretical physicists had predicted these particles by mathematically estimating the conditions that existed a quadrillionth of a second or less after the “Big Bang” that many scientists believe was the start of the universe.
The conditions that existed at that time--extremely high temperatures and pressures--are simulated on a very small scale by particle accelerators like the proposed super collider.
Not all the particles predicted by theorists have been found, however--the Higgs boson being the one most often cited--and no theory can explain the entire universe. That is why the super collider has been proposed. Scientists say it would be powerful enough to prove the existence of the Higgs boson, named after British scientist Peter W. Higgs, who predicted its existence, and could discover new clues for theorists to use in advancing theories of the universe.
“Higgs is the place-holder for the sum total of our ignorance,” said Leon Lederman, director of the Fermi National Accelerator Laboratory near Chicago. “It is the rug under which we sweep all that we don’t understand. It’s where we collect all our puzzles.”
Confirming that particle is very important to scientists, he said, although finding something else would almost be better.
“It is a little like Columbus sailing west from Spain,” explained Steven Weinberg, a theoretical physicist at the University of Texas. “He said he was going to the Indies. But if he had been more careful, he might have said that by sailing far enough west he was sure to get to the Indies--unless something equally interesting got in the way. As it happened, of course, a whole new world was in the way.”
The Department of Energy contends that high-energy physics already has produced ancillary benefits, from advances in nuclear medicine to the invention of ion implantation, which makes possible the atom-by-atom construction of materials with new properties.
The practical applications of much new knowledge will take time, scientists say, just as it took decades for James Maxwell’s unification of magnetism and electricity to produce radios, televisions and other devices.
THE SUPERCONDUCTING SUPER COLLIDER The superconducting super collider would be the largest and costliest scientific instrument in history. The goal is to accelerate streams of tiny subatomic particles in opposite directions at extremely high speeds, then smash them into one another. In theory, the high-powered collision would break apart the smallest known subatomic particles--quarks--into even tinier building blocks, helping scientists understand the basic structure of matter. How Small Can Matter Be? Imagine an atom being about as big a medium-sized office building. Its nucleus then, would be about the size of a basketball in the very center of the building. A proton inside the nucleus would be the size of a Ping-Pong ball. A quark, one of the smallest findamental particles yet discovered, would be a grain of sand. The new super collider would try to split that grain of sand. How the Super collider Would Work 1. Hydrogen atoms are electrically charged (ionized) so they can be aimed with magnets.
2. The ions atomsare injected into a linear accelerator (LINAC) which uses pulses of radio waves to accelerate them much as waves at the beach accelerate surfers.
3. At the end of the LINAC, the ions are swept into a low-energy booster that strips away the atoms’ two electrons, leaving electrically charged protons.
4. The protons are further accelerated in the medium-energy booster, and then in the high-energy booster.
5. In the double-barrelled main ring, thousands of extremely strong, 50-foot-long magnets keep the two powerful proton streams in alignment as they travel in opposite directions at nearly the speed of light. The streams are about the thickness of a drinking straw.
6. In “collision halls”--warehouse-sized laboratories-- focusing magnets reduce the streams to less than the width of a human hair. The opposing streams are aimed at each other to create the collisions.
