Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Characterization of the micropulse bunch lengths and phase stability of the drive laser and the electron beam continue to be of interest at the Fermilab A0 Photoinjector facility. Upgrades to the existing Hamamatsu C5680 streak camera were identified, and initially a synchroscan unit tuned to 81.25 MHz was installed to provide a method for synchronous summing of the micropulses from the drive laser and the optical transition radiation (OTR) generated by the e-beam. A phase-locked delay box was also added to the system to provide phase stability of ~1 ps over tens of minutes. Initial e-beam measurements identified a significant space-charge effect on the bunch length. Recent measurements with a re-optimized transverse emittance allowed the reduction of the micropulse number from 50 to 10 with 1 nC each to obtain a useful streak image. This increased signal also would facilitate dual-sweep operations of the streak camera to explore macropulse effects. Installation of the recently procured dual-sweep module in the mainframe has now been done. Initial commissioning results and sub-macropulse effects in the beams will be presented as available.
University of Pennsylvania, Philadelphia, Pennsylvania
Fermilab, Batavia
The Fermilab A0 Photoinjector is a 16 MeV high-intensity, low emittance electron linac used for advanced accelerator R&D. To achieve a high quality beam here it is important to maintain a stable laser in terms of both intensity and timing. This paper presents our measurement of the laser timing jitter, which is the random late or early arrival of the laser pulse. The seed laser timing jitter has been measured to less than 200 fs, by examining the power spectrum of the signal of a fast photodiode illuminated by it. The pulsed and pumped laser timing jitter has been measured with limited resolution to less than 1.4 ps, by examining the phase of a cavity impulsively excited by the signal from a fast photodiode illuminated by the laser pulse.
Rutgers University, The State University of New Jersey, Piscataway, New Jersey
Fermilab, Batavia
Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
An experiment has been developed at the Fermilab A0 Photoinjector Lab to demonstrate the exchange of longitudinal emittance with the horizontal emittance. Our apparatus consists of a 3.9 GHz TM110 deflecting rf cavity placed between two magnetic dogleg channels. The first dogleg generates the needed dispersion to appropriately position the off-momentum electrons in the TM110 cavity. The TM110 cavity reduces the momentum spread and imparts a time dependent transverse kick. The second dogleg finishes the exchange and yields the exchange of the emittances. We report on the measurement of the exchange beamline matrix elements as well as an inital report on measuring the exchange emittances directly.
