Researchers from the Physics Department at UNM, in collaboration with researchers at the Collider Detector at Fermilab or CDF and the Department of Energy’s Fermi National Accelerator Laboratory, recently discovered a rare type of particles that are exotic relatives of the much more common proton and neutron.
Photo: The Fermilab accelerator complex accelerates protons and antiprotons close to the speed of light. The Tevatron, four miles in circumference, is the world’s most powerful accelerator, producing collisions which recreate the conditions of the early universe.
UNM Professors Igor Gorelov and Sally Seidel and post-doctorate fellow Elena Vataga worked in close collaboration with CDF physicists from Fermilab and Johns Hopkins University on this significant discovery.
The CDF is a collaboration of 700 physicists studying high-energy particle collisions in the CDF detector at the world’s most powerful particle accelerator Tevatron, located outside of Chicago in Batavia, Ill. The goal is to discover the identity and properties of the particles that make up the universe and to understand the forces and interactions between those particles.
Protons and neutrons, which form the nucleus of an atom, are made up of still smaller particles called quarks. The new particle discovered by UNM researchers is named Sigma-sub-b [Σb]. Sigma-sub-b is similar to a proton or neutron in which one of the light quarks is substituted by the second-heaviest quark called the bottom quark.
“Sigma-sub-b’s are the exotic heavy partners of protons. They abundantly existed at the very first moments of the formation of our universe right after the so-called Big Bang explosion,” Gorelov said.
According to scientists, the particles are like rare jewels mined out of the research data. Piece by piece, researchers are developing a better picture of how matter is built out of quarks. In the process more is learned about the subatomic forces that hold quarks together and tear them apart.
The Tevatron collider accelerates protons and antiprotons close to the speed of light and makes them collide. In the collisions, energy transforms into mass, according to Einstein’s famous equation E=mc2. To beat the low odds of producing bottom quarks – which in turn transform into the Sigma-sub-b according to the laws of quantum physics – scientists take advantage of the billions of collisions produced by the Tevatron each second.
“We ran our software over hundreds of terabytes of data from hundred trillion proton-antiproton collisions recorded by the CDF detector and we found only about 240 Sigma-sub-b candidates,” Vataga said.
Photo: The CDF detector, about the size of a 3-story house, weighs about 6,000 tons. Its subsystems record the “debris” emerging from high-energy proton-antiproton collisions, unveiling the secrets of the early universe. The detector surrounds the collision point and records the path, energy and charge of exotic, short-lived particles emerging from the collisions.
Photos courtesy Fermilab Visual Media Services
Contact: Steve Carr, (505) 277-1821; e-mail: scarr@unm.edu