Thomas Jefferson National Accelerator Facility

The Thomas Jefferson National Accelerator Facility (Jefferson Lab from now on) is a new $600 million laboratory in the Tidewater region of Virginia. It employs approximately 500 people.

The Accelerator

The electron beam begins its first orbit at the injector and proceeds through the underground racetrack-shaped accelerator tunnel at nearly the speed of light. Here is a movie of the process.

The accelerator uses superconducting radio-frequency technology to drive electrons to higher and higher energies. A refrigeration plant, called the Central Helium Liquifier, provides liquid helium for ultra-low-temperature (-456 F), superconducting operation.

Jefferson Lab 's accelerator tunnel has more than 2,200 magnets in 58 varieties. They range in size from a few inches to two yards and weigh as much as 5 tons. The accelerator is controlled and monitored by computers in the Machine Control Center that track, manage, and respond to the more than 100,000 simultaneous signals and 25,000 hardware control points.

Jefferson Lab 's electron beam travels around the 7/8 mile tunnel five times in 30 millionths of a second. At that speed, the electron beam could circle the earth 7 1/2 times in one second.

The mass of an object increases as its speed increases. At nearly the speed of light, the electrons in Jefferson Lab's beam increase in mass 7,830 times. The electron beam can be split for use by three simultaneous experiments in the end stations, which are circular, domed chambers with diameters ranging from 98 to 172 feet. Special equipment in each hall records the interactions between incoming electrons and the target materials. The continuous electron beam is necessary to accumulate data at an efficient rate yet ensure that each interaction is separate enough to be fully observed.

The laboratory gives scientists a unique and unprecedented probe to study quarks, the particles that make up protons and neutrons in the atoms nucleus. The accelerator delivers a continuous beam to a target, like hydrogen, carbon, gold or lead. When the beam collides with its target,particles scatter. By studying the speed , direction , and energy of the scattered particles scientists will learn more about how the nucleus is put together.

Detectors

The electrons end their journies in one of the experimental halls at the western end of the site. There information on the collision is collected and analysed by a bank of workstations.

Jefferson Lab's Purpose

Jefferson Lab was designed to investigate how quarks and gluons combine to create nucleons and nuclei. It will also be able to search for fundamentally new types of particles called hybrids and glueballs.