A top priority for the field of nuclear physics in the U.S. since the late 1970's, the Thomas Jefferson National Accelerator Facility (TJNAF) was approved for construction by Congress in 1987. This project was originally called CEBAF, the Continuous Electron Beam Accelerator Facility. It came into operation in Newport News, Virginia, in 1994. The first physics results were reported at the Particles and Nuclei International Conference (PANIC) held at the College of William and Mary in Williamsburg in 1996. The experimental program at TJNAF is now fully underway, and one can look forward to a steady output of significant experimental results providing insight into the structure of hadronic matter well into the 21st century.

Some of the new experimental results from TJNAF have already been referred to in this book, and we discuss more of the anticipated program in the next chapter. In order to fully understand the future opportunities this facility provides, we present a brief overview of the existing accelerator and major experimental equipment.

There is no single feature that makes TJNAF unique; each of the characteristics has been achieved previously at one location or another. Rather, it is the combination of properties that makes TJNAF (CEBAF) the world's most powerful microscope for looking at the nucleus. A schematic of the accelerator complex at TJNAF is shown in Fig. 29.1.

The accelerator itself is in the form of a racetrack 10m underground. The basic accelerating structure is a superconducting niobium cavity fed with microwave power at a frequency of v = 1497 MHz.