The ratios μpGEp/GMp from two JLab recoil polarization experiments, compared to the Rosenbluth separation data (left) and with several theoretical calculations (right).
Jefferson Lab has four experimental halls. The smallest of these is Hall B, measuring roughly 98 ft in diameter and 65 ft from floor to ceiling. From 1995 to 2012, the heart of the Hall B physics program involved the use of a particle detector system known as “CLAS,” an acronym that stands for the CEBAF Large Acceptance Spectrometer. This magnetic spectrometer was based on a superconducting toroid and measured the trajectories of charged particles created in interactions of the beam with a fixed target to determine their momenta.
An effect of color confinement in quantum chromodynamics (QCD) is that traditional perturbation theory breaks down at large distances and low energies. A quantitative understanding of the strong interaction in this region remains one of the greatest intellectual challenges in physics. The symmetries of QCD in the chiral limit (in which the quark mass vanishes) are an important element in resolving this problem.
One of the principal challenges of QCD is to bridge the small- and large-scale behavior of the strong nuclear interactions. At short distances, perturbative QCD is very successful in describing nucleon structure in terms of quarks and gluons. At large distances, the effects of confinement impose a more efficient description in terms of collective hadron degrees of freedom. Despite this apparent dichotomy, an intriguing connection has been observed between the low- and high-energy data on nucleon structure functions, which is referred to as "quark-hadron duality."
Jefferson Lab has four experimental halls. Hall A is the largest of these four experimental staging areas. It is 174 feet across and 80 feet tall from the floor to the highest spot on its domed ceiling. The foundation for the hall is 35 feet below ground.
Hall A is outfitted with two primary detector systems – both high-resolution spectrometers, each weighing about 3 million pounds or 1,500 short tons. The hall is used primarily for experiments that study the structure of the nucleus and the protons and neutrons it contains.
Jefferson Lab has four experimental halls. Hall C is 150 feet in diameter and 60 feet tall.
Hall C houses two large spectrometers, the High Momentum Spectrometer and the new Super High Momentum Spectrometer. The hall also provides space for temporary installation of other detectors such as the Neutral Particle Spectrometer and the Large Acceptance Detector.
The research equipment in Hall C is used to study form factors and 3-D structure of simple quark systems, and short range structure in nuclei.
Thomas Jefferson National Accelerator Facility is a U.S. Department of Energy Office of Science national laboratory. Jefferson Lab's unique and exciting mission is to expand our knowledge of the universe by studying the basic building blocks of matter within the nucleus: subatomic particles known as quarks and gluons.
