Charlie Sinclair: His Distinguished Career

During his early professional career, Dr. Sinclair played a lead role in the development of methods for the generation of highly polarized and monochromatized high energy gamma ray beams. Polarized gamma beams were successfully developed by three techniques:

  • Compton backscattering of polarized laser light;
  • collimation of coherent bremsstrahlung from very thin diamond radiators;
  • and attenuation of bremsstrahlung by coherent pair production.
He was a member of the experimental groups which employed these beams in photoproduction studies utilizing both bubble chambers and magnetic spectrometers. These studies provided the first demonstration of s-channel helicity conservation in vector meson photoproduction, and the dominance of unnatural parity exchange in all pseudoscalar meson photoproduction reactions.

Following this work, Dr. Sinclair's interests moved to the production, measurement, and experimental utilization of high energy polarized electron beams. He participated in the development of the first Mφller polarimeter to measure high energy electron polarization, and in the first measurements of polarized electron-polarized proton scattering at high energy. He played a very major role in the development of the GaAs polarized electron source as an accelerator injector, and in the use of this source at SLAC for the first measurements of parity non-conservation in high energy inelastic electron scattering from deuterium. He was an active member of a small group which developed the first laser Compton polarimeter, and made the first measurements of the polarization of a circulating positron beam in an electron-positron storage ring. More recently, he has led the development of a very high precision Mott polarimeter operating at MeV energies.

Soon after the discovery of the J/φ and φ' particles, he worked with a group which made the first measurements of the photoproduction of these particles, clearly demonstrating their hadronic character.

Over time, Dr. Sinclair's interests moved into a variety of accelerator physics and technology related areas. He has developed several high peak current and very high voltage photoemission electron guns employing GaAs cathodes, and has planned and conducted a number of experiments designed to bring photoemission cathodes to their full potential. He had a lead role in the development of the high current single bunch injector for the Stanford Linear Collider. He participated in the first development of a superconducting RF electron gun with a photoemission cathode.

Since coming to Jefferson Laboratory (formerly CEBAF), Dr. Sinclair has worked primarily on the development of various accelerator subsystems, including the original thermionic injector, the vacuum system for the full accelerator, the polarized injector for the accelerator, the RF separators for beam extraction, the high voltage DC injector for the FEL, many beam diagnostic devices, and the beam dumps for the full power accelerated beam. He led the CEBAF Front End Test, which demonstrated high average current energy recovery, and established the stability of the CEBAF accelerator against transverse beam breakup. He served as the Head of the Accelerator Operations Department during the commissioning of the full accelerator. He led the Injector Group for many years. More recently, he served as Associate Director (acting) of the Accelerator Division, and is now Deputy Head of the Accelerator Division.

Dr. Sinclair has participated in the research of six Ph.D. students (Bruce Dunham, Nicholas Sereno, David Engwall, and Joseph Grames at the University of Illinois, Achim Michalke at the University of Wuppertal, and Thomas Venhaus at the College of William and Mary). He has taught a course on Electron Injectors in conjunction with the U.S. Particle Accelerator School in Beijing (November 1998) and at Vanderbilt University (January 1999).