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Mission
Jefferson Laboratory's Center for Injectors and Sources (CIS) develops and maintains the sources of high polarization (85%) electron beams used in the CEBAF accelerator at Jefferson Laboratory. These sources are based upon photoemission from prepared gallium arsenide semiconductor material. Our group has interest in cutting-edge technologies of electron gun design, radio-frequency syncrhonized lasers, ultra-high vacuum and electron beam polarimetry.
EGG are (l to r) Ken Surles-Law, Jim Clark, John Hansknecht, Josh Brittian,
Phil Adderley, Marcy Stutzman, Joe Grames, and group leader Matt Poelker.
July 2006
Upon completion of a one month summer shutdown, all halls are being driven by fiber lasers. Hall C has a dedicated fiber laser. Hall A&B are sharing a second fiber laser.
Ti-Sapphire lasers are no longer needed. This would not have been possible had it not been for the advancements in photo-cathode material. Superlattice cathodes provide excellent polarization at the 780nm wavelength produced by the fiber lasers.
June 2006
John Hansknecht and Matt Poelker describe the new fiber laser system in a recently published paper, "Synchronous Photoinjection using a Frequency-Doubled Gain-Switched Fiber-Coupled Seed Laser and ErYb-Doped Amplifier".
May 2006
A significant portion of the CEBAF program was recently run using the new optical fiber based laser system built by John Hansknecht and Matt Poelker. This laser will replace our mode-locked Ti:Sapphire lasers owing to their permanent synchronization with the accelerator radio-frequency and exceptionally higher power output (>700 mW at 780 nm).
April 2006
Marcy Stutzman and the electron gun group are recognized in the laboratory newsletter OnTarget for contributing to the viability of high polarization superlattice photocathodes for the CEBAF program.
February 28, 2006
A defining moment in CEBAF history. At 22:30 the Hall C drive laser was switched from a Ti-Sapphire laser to the new experimental fiber laser. It was never to return.
November 2005
A fruitful time for meetings and discussion - Marcy Stutzman and Phil Adderley just returned from the AVS 2005 (American Vacuum Society) meeting in Boston, MA and Matt Poelker is preparing for PST 2005 (Polarized Sources and Targets) in Tokyo, Japan. Locally, the Hall A Proton Parity EXperiment (HAPPEX) has been running with high polarization (86%) from strained superlattice GaAs and our best ever parity quality beam.
July 2005
Jennifer Cooper, a student intern with our group last summer, has published her results from our Injector Test Stand in the undergraduate, peer-reviewed The Journal of Young Investigators. You can find her submission here, for which she won the Best Undergraduate Paper/Poster Award at the Davidson College Society of Physics Students conference in Charlottle, NC last year.
January 2005
Happy New Year! We began the year by delivering high average current (>200 microAmps) at high polarization (~85%) from a high polarization superlattice photocathode.
December 2004
This month Daniel Charles, a student in our group, receives his Bachelor of Science in Physics degree from Christopher Newport University (click here). Congratulations Daniel !
November 2004
Phil presents a poster at the American Vacuum Society 53rd International Symposium.
October 2004
Matt & Joe make presentations at the PESP 2004 workshop hosted in Mainz, Germany.
May 2004
A superlattice GaAs photocathode has been sucessfully installed and activated in Gun 3. It provided the highest polarization ever measured in the CEBAF accelerator (81%), with high quantum efficiency. It will be provide beam to the next experiment.
March 2002
Our Gun3 strained layer GaAs photocathode has delivered above 70% polarization for more than a year with only three activations.
January 2000
The CEBAF injector is augmented with two identical 100 keV polarized electron guns.
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Last maintained on Sept. 19, 2006 by grames@jlab.org.
