Synchroscan streak camera imaging at a 15-MeV photoinjector with emittance exchange

At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a fast single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10-20ps. We have upgraded the camera system with the synchroscan module tuned to 81.25MHz to provide synchronous summing capability with less than 1.5ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of ~1ps over 10s of minutes. These steps allowed us to measure both the UV laser pulse train at 263nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 0.25-1nC per micropulse. The phase-locked delay box allowed us to assess chromatic temporal effects and instigated another upgrade to an all-mirror input optics barrel. In addition, we added a slow sweep horizontal deflection plug-in unit to provide dual-sweep capability for the streak camera. We report on a series of measurements made during the commissioning of these upgrades including bunch-length and phase effects using the emittance exchange beamline and simultaneous imaging of a UV drive laser component, OTR, and the 800nm diagnostics laser.Comment: 26 p

Single-shot electro-optic sampling of coherent transition radiation at the A0 Photoinjector

Future collider applications and present high-gradient laser plasma wakefield accelerators operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. Potential applications in shot-to-shot, non-interceptive diagnostics continue to be pursued for live beam monitoring of collider and pump-probe experiments. Related to our developing work with electro-optic imaging, we present results on single-shot electro-optic sampling of the coherent transition radiation from bunches generated at the A0 photoinjector.Comment: 3 p

Conversion of a transverse density modulation into a longitudinal phase space modulation using an emittance exchange technique

We report on an experiment to produce a train of sub-picosecond microbunches using a transverse-to-longitudinal emittance exchange technique. The generation of a modulation on the longitudinal phase space is done by converting an initial horizontal modulation produced using a multislits mask. The preliminary experimental data clearly demonstrate the conversion process. To date only the final energy modulation has been measured. However numerical simulations, in qualitative agreement with the measurements, indicate that the conversion process should also introduce a temporal modulation.Comment: 4 pages, 6 figures. Submitted to the proceedings of the Physics and Applications of High-Brightness Electron Beams (HBEB09), Nov. 16-19, 2009, Maui H

Initial beam-profiling tests with the NML prototype station at the Fermilab A0 Photoinjector

The beam-profile diagnostics station prototype for the superconducting rf electron linac being constructed at Fermilab at the New Muon Lab has been tested. The station uses intercepting radiation converter screens for the low-power beam mode: either a 100-\mu m thick YAG:Ce single crystal scintillator or a 1-\mu m thin Al optical transition radiation (OTR) foil. The screens are oriented with the surface perpendicular to the beam direction. A downstream mirror with its surface at 45 degrees to the beam direction is used to direct the radiation into the optical transport. The optical system has better than 20 (10) \mu m rms spatial resolution when covering a vertical field of view of 18 (5) mm. The initial tests were performed at the A0 Photoinjector at a beam energy of ~15 MeV and with micropulse charges from 25 to 500 pC for beam sizes of 45 to 250 microns. Example results will be presented.Comment: 3 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1 Apr 2011. New York, US

TeV/m Nano-Accelerator: Current Status of CNT-Channeling Acceleration Experiment

Crystal channeling technology has offered various opportunities in the accelerator community with a viability of ultrahigh gradient (TV/m) acceleration for future HEP collider. The major challenge of channeling acceleration is that ultimate acceleration gradients might require a high power driver in the hard x-ray regime (~ 40 keV). This x-ray energy exceeds those for x-rays as of today, although x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. Moreover, only disposable crystal accelerators are possible at such high externally excited fields which would exceed the ionization thresholds destroying the atomic structure, so acceleration will take place only in a short time before full dissociation of the lattice. Carbon-based nanostructures have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration. This paper presents a beam-driven channeling acceleration concept with CNTs and discusses feasible experiments with the Advanced Superconducting Test Accelerator (ASTA) in Fermilab.Comment: 5 pp. arXiv admin note: text overlap with arXiv:1502.0207