439 research outputs found
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
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