Initial high-energy results reported from Jefferson Lab

17 Jun 2002

This new nuclear physics facility in Newport News, Virginia explores the interface between the physics of the nucleus and the physics of individual protons and neutrons(made of quarks held together by particles known as gluons).

The main machine at Jefferson Lab is the Continuous Electron Beam Accelerator Facility (CEBAF), which accelerates continuous streams of electrons to energies of 4 GeV (with amaximum energy of 8 GeV planned for the future); the electrons are then diverted to one of three experimental halls where they collide with fixed targets containing nuclei.

At the recent APS meeting Rolf Ent of Jefferson Lab described how electron collisions withnuclei are ejecting protons from nuclei at a greater rate than anticipated by the present theories on the subject. Exploring how gamma rays break up deuterons, Haiyan Gao of Argonne presented measurements showing that the quark substructure inside the deuteron must be taken into account to properly understand the breakup.