Compton X-Ray Laboratory
|In collaboration with U.C. Davis,
a program is underway at SLAC to develop a source for generating
monoenergetic, tuneable X-rays in the multi-keV domain (20-85
keV). The goal is to demonstrate a proof-of principle device
useful in the diagnosis and treatment of cancer.
The X-rays are generated via the Compton Effect in a (nearly) head-on collision of a multi-MeV electron beam with a high power, infrared laser beam (1-2 TW). The backscattered photons will be in the KeV energy regime, determined by the electron beam energy. Since the requirement of monoenergetic X-rays depends critically on the electron beam energy-uniformity and quality, a laser driven RF gun is used to generate sub-picosecond electron bunches. Further acceleration is accomplished through the use of a high gradient X-band accelerator structure developed for the Next Linear Collider (NLC).
The key beamline components in this experiment are the RF gun, emittance compensating solenoid, mirror chamber, accelerator, magnetic focusing elements diagnostic chamber, an interaction chamber where the photon and electron beams collide and a final observation chamber. Each of the chambers is equipped with a removable Ce:YAG scintillator to permit beam optimization along the beamline. In addition, metallized pellicles are installed in some of the chambers for OTR observation and slits for emittance measurements. A schematic of the setup is shown below. The RF setup and the high power laser system are located in a radiation shielded enclosure with RF power supplied externally by two X-band 60 MW NLC klystrons. Table 1 lists the overall capabilities and design requirements of the complete system.
Table 1. Operating parameters