| Paper | Title | Page |
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| MOPEA084 | Timestamping for Relativistic Electron Diffraction | 271 |
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High brightness ultrashort electron beams have been produced at the UCLA Pegasus photoinjector lab for use in time-resolved electron diffraction applications. Beams have been generated with high enough brightness to obtain single shot diffraction patterns of thin solid targets. These beams contain a few pC at 3.5 MeV in a 200 fs pulse. Pump-probe experiments on thin metal foils have already shown promising results on picosecond time scales*. Current research focuses on materials with processes that are observable on the sub-100 fs scale. To overcome rf jitter and synchronization problems, electro-optic sampling is used as a single shot time-of-arrival diagnostic** to help reconstruct the melting "movie." *P. Musumeci, et al., Rev. Sci. Instrum. 80, 013302 (2009) |
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| MOPE092 | Ultrashort Bunch Length Diagnostic with Sub-femtosecond Resolution | 1200 |
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For successful operation and beam characterization, fourth generation light sources require the observation of sub-picosecond bunches with femtosecond resolution. In this paper, we report on the design and development of a novel technique to achieve sub-femtosecond temporal resolution of high brightness bunches. The technique involves the coupling of the electron beam to a high power laser in an undulator field, which is optimized to maximize the angular deviation of the bunch. The beam angular components are imaged on a distant screen yielding a sweep across angles in one dimension. The addition of an x-band deflecting cavity downstream of the undulator creates another sweep of the beam, in the perpendicular dimension. The temporal resolution of the bunch is dependent on the seed laser wavelength and the spatial resolution of the screen. Initial calculations show that for a CO2 laser (T~30fs) and a phosphor screen (~50micron spatial resolution), the longitudinal resolution is approximately l/200 of the laser wavelength, or ~150 attoseconds. |
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| TUPE021 | Electron Beam Conditioning with IR/UV Laser on the Cathode | 2182 |
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Shining a photocathode at the same time with an UV laser able to extract electrons and an IR laser properly tuned could influence the way the electron beam is generated. Such a process is under investigation at SPARC, through direct measurements, as much as through computer codes assessment studies. |
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| THPEC015 | Breaking the Attosecond, Angstrom and TV/m Field Barriers with Ultra-fast Electron Beams | 4080 |
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Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This uses of very low charge beams, which may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the Stanford X-ray FEL (LCLS, first of its kind, built with essential UCLA leadership) have produced ~2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments at UCLA in cryogenic undulator technology, to create compact accelerator/undulator systems that can lase below 0.15 Angstroms, or be used to permit 1.5 Angstrom operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications. |