Initial tests of the dual-sweep streak camera system planned for APS particle-beam diagnostics Page: 1 of 5
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INITIAL TESTS OF THE DUAL-SWEEP STREAK CAMERA SYSTEM
PLANNED FOR APS PARTICLE-BEAM DIAGNOSTICS*
A. Lumpkin, B. Yang, and W. Gai
Argonne National Laboratory, 9700 S. Cass, Argonne, IL 60439 USA
W. Cieslik
Hamamatsu Photonic Systems, Bridgewater, NJ 08807 USAAbstract
Initial tests of a dual-sweep streak system planned for use
on the Advanced Photon Source (APS) have been performed
using assets of the Argonne Wakefield Accelerator (AWA)
facility. The short light pulses from the photoelectric injector
drive laser in both the visible (=496 nm, At-1.5 ps (FWHM)),
and the ultraviolet (X= 248 nm, At-5 ps (FWHM)) were used.
Both a UV-visible S20 photocathode streak tube and a UV-to-
x-ray Au photocathode streak tube were tested. Calibration
data with an etalon were also obtained. A sample of dual-
sweep streak data using optical synchrotron radiation on the
APS injector synchrotron is also presented.
I. INTRODUCTION
The Advanced Photon Source will be a third-generation
synchrotron radiation facility for the hard x-ray (10-100 keV)
research community. The need to measure and monitor parti-
cle and photon beam parameters in the single bunch (10 ps),
bunch-to-bunch (3 to 180 ns), and turn-by-turn (3.68 )is) times-
cales has resulted in the choice of a dual-sweep streak camera
system [1]. Initial laboratory tests with 50- and 80-ps
(FWHM) laser diodes were performed. Tests at the Argonne
Wakefield Accelerator [2,3] (AWA) using the short-pulsed
photoelectric injector drive laser were undertaken to test both
UV-visible (S20) and UV-x-ray (Au-based) photocathode
streak tubes. The 1.5-ps (FWHM), 496-nm component and the
5-ps (FWHM), 248-nm component were used. Plans to use
bremsstrahlung x-rays generated by the linac beam in a short
pulsed mode hitting a foil were limited by inadequate photon
statistics in the first geometry tried.
II. EXPERIMENTAL BACKGROUND
The initial evaluations of the streak camera were with
laser diodes whose bunch lengths were many times longer than
the specified camera resolution. The nominal 1.5 ps (FWHM)
resolution could be better evaluated with a short bunch in the
1-2 ps regime that was available at the AWA.
The AWA project in its early phase includes an L-band,
20-MeV drive linac with a high brightness photoelectric injec-
tor (PEI) capable of delivering 2-MeV, 100-nC, 20-ps
(FWHM) bunches to the linac (see Fig. 1). The drive laser for
this source is a pulsed laser system constructed jointly by
Coherent-Lambda Physics which is described in [3]. A har-
monic tripled mode-locked Nd:YAG laser is used to pump the
* Work supported by the U.S. Department of Energy, Office of Basic
Energy Sciences, under Contract No. W-31-109-ENG-38.
D~STRIB 1SON OF THIS DOCUMENT IS UNL[MITEDdye laser. For our test purposes, the laser was adjusted to pro-
vide 1-2 ps (FWHM) pulses at 496 nm. Amplification of the
subsequent short UV pulses at 248 nm was done in a single
stage KrF excimer laser whose observed output pulse length
was 4 to 5 ps (FWHM).
J f
PHOTOCATHODE
CONTROL LASER tOM
ROOM
Figure 1: Schematic of the Argonne Wakefield Accelerator Facility.
The drive laser and lab, the control room, and the accelerator in the
shielded tunnel are indicated.
In our initial setup, as shown in Fig. 2, we used the
amplified, 248-nm component from the drive laser system to
evaluate the streak camera tubes' resolutions. An autocorrela-
tor that was on-line, but sampling the green component, served
as an independent bunch length monitor. The Hamamatsu
C5680 with a single-shot fast sweep plug-in unit was aligned
to the laser beam. A beam splitter was used to provide both a
signal to a photodiode whose output generated an electrical
trigger for the camera sweep and a laser beam that was appro-
priately delayed by transport distance to the entrance slit of the
streak tube.
In a second mode, shown in Fig. 3, we split off part of the
dye laser component at 496 nm which was also being moni-
tored by the autocorrelator. The autocorrelator monitor nomi-
nally indicated bunch lengths of 1 to 2 ps (FWHM) in the
baseline operating mode.
Both the UV-visible (S20) photocathode (PC) tube and the
Au photocathode tube were evaluated. In the latter case, a
quartz window on the front flange allowed UV photons to hit
the PC. We also used a front flange with a Be window for the
planned test with x-rays. A portable pumping station was used
to take the tube pressure to 2x 10- Torr. For both these tests,
the camera was positioned off-axis near the end of the linac.
Part of the drive laser beam for the PEI was directed to the
streak camera.MASILn
The submitted manuscript has been authored
by a contractor of the U. S. Government
under contract No. W-31-109ENG-38.
Accordingly, the U. S. Government retains a
nonexclusive, royalty-free license to publish
or reproduce the published form of this
contribution, or allow others to do so, for
U. S. Government purposes.
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Lumpkin, A.; Yang, B.; Gai, W. & Cieslik, W. Initial tests of the dual-sweep streak camera system planned for APS particle-beam diagnostics, article, July 1, 1995; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc787799/m1/1/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.