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| IT05 | Single Shot Electron-Beam Bunch Length Measurements | diagnostics, instrumentation, monitoring, electro-magnetic fields, wakefield | 20 | ||
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It is recognised by the Instrumentation community that 4th generation
light sources (like TESLA, LCLS) are posing some of the most stringent
requirements on beam diagnostics. Among these, the single-shot
electro-optic measurement of the bunch length and shape in the
sub-picosecond domain is an ongoing development.
The electro-optic detection method makes use of the fact that the local
electric field of a highly relativistic electron bunch moving in a
straight line is almost entirely concentrated perpendicular to its
direction of motion. This electric field makes an electro-optic crystal
placed in the vicinity of the beam birefringent. The amount of
birefringence depends on the electric field and is probed by monitoring
the change of polarization of the wavelength components of a chirped,
synchronized Ti:sapphire laser pulse.
This talk will provide details of the experimental setup at the Free
Electron Laser for Infrared eXperiments (FELIX) in Nieuwegein, The
Netherlands, where single shot images have been obtained of 1.7 ps long
electron bunches (beam energy 46 MeV, charge per bunch 200 pC).
Furthermore, future upgrading possibilities will be discussed.
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| CT03 | Beam Instrumentation for the Single Electron DAΦNE Beam Test Facility | diagnostics, instrumentation, linac, controls, positrons | 59 | ||
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The DAΦNE Beam Test Facility (BTF) has been successfully commissioned in
February 2002, and started operation in November of the same year.
Although the BTF is a beam transfer line optimized for single particle
production, mainly for high energy detectors calibration, it can provide
electrons and positrons in a wide range of multiplicity: between 1-1010,
with energies from a few tens of MeV up to 800 MeV. The large
multiplicity range requires many different diagnostic devices, from
high-energy calorimeters and ionization/fluorescence chambers in the few
particles range, to standard beam diagnostics systems. The schemes of
operation, the commissioning results, as well as the beam diagnostics are
presented.
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| CT04 | The Beam Inhibit System for TTF II | diagnostics, instrumentation, linac, free-electron-laser | 62 | ||
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The new generation of light sources based on SASE Free-Electron-Lasers
driven by LINACs operate with electron beams with high beam currents and
duty cycles. This is especially true for the superconducting machines
like TTF II and the X-RAY FEL, under construction or planning at DESY.
Elaborate fast protections systems are required not only to protect the
machine from electron beams hitting and destroying the vacuum chamber,
but also to prevent the machine from running at high loss levels,
dangerous for components like the FEL undulator.
This paper will give an overview over the different protection systems
currently under construction for TTF II. The very fast systems, based on
transmission measurements and distributed loss detection monitors, will
be described in detail. This description will include the fast
electronics to collect and to transmit the different interlock signals.
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| CT05 | Beam Loss Detection at Radiation Source ELBE | diagnostics, instrumentation, linac, radiation, beam-losses, beam-transport | 65 | ||
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The Rossendorf superconducting Electron Linac of high Brilliance and low
Emittance (ELBE) delivers an 40 MeV, 1 mA cw-beam for different
applications such as bremsstrahlung production, electron channelling,
free-electron lasers or secondary particle beam generation. In this
energy region in case of collisions of the electron beam with the pipe
nearly all beam power will be deposited into the pipe material. Therefore
a reliable beam loss monitoring is essential for machine protection
at ELBE. Different systems basing on photo multipliers, compton diodes
and long ionization chambers were studied. The pros and cons of the
different systems will be discussed. Ionization chambers based on
air-isolated RF cables installed some cm away parallel to the beam line
turned out to be the optimal solution. The beam shut-off threshold was
adjusted to 1 μC integral charge loss during a 100 ms time interval. Due
to the favourable geometry the monitor sensitivity varies less than ±50%
along the beam line (different shielding conditions).
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| PM05 | Optical Transmission Line For Streak Camera Measurements at Pitz | diagnostics, gun, longitudinal-dynamics, optics, PITZ | 98 | ||
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The photoinjector injector test facility at DESY Zeuthen (PITZ) [1]
produces electrons with a momentum of about 4 MeV/c. It is the aim to
measure the temporal characteristics of the electron bunch train and
single bunches with high accuracy of the order of 1 ps and less. Several
types of streak cameras will be used in combination with different
radiators which transform particle energy in light. The problem to be
solved is the light transport over a distance of about 27 m. Basic demands
to the optical system and design principles will be explained. The
optical and technical solutions will be presented. The strategy of
adjustment and commissioning of the optical system will be described. The
system contains switchable optics to use different radiators (OTR,
Cherenkov radiators). Diagnostic tools are foreseen at different
positions along the optical axis. The results of different measurements
in the lab and using the original system will be presented. The problems
on the minimalization of the time dipersion in the system will be
discussed.
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[1] F.Stephan, et al., Photo injector test facility under construction at DESY Zeuthen, FEL 2000, Durham |
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| PM10 | Characterisation of Fast Faraday Cups at the ELETTRA Linac | diagnostics, ELETTRA, instrumentation, linac | 113 | ||
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A major upgrade of the ELETTRA injector is currently on going: the 1 GeV
LINAC will be replaced with a 100 MeV LINAC and a 2.5 GeV Booster
Synchrotron. A new set of diagnostics is now under development for these
two new machines. The new Fast Tune measurement system for the Booster
represents a significant improvement as compared to the present Tune
measurement system.
With the Booster cycling at 3 Hz, horizontal and vertical tunes have to be
measured during the energy ramp, whose duration is 160 ms. To completely
characterise the dynamics of the Booster during the energy ramp, a set of
25 tune values has been required, corresponding to a 6.4 ms interval
between successive measurements. The accuracy of this measurement is
<10-3. Such frequency spans are achievable using a Real Time Spectrum
Analyser (Tektronix 3026), which is a fast sampling instrument with
built-in FFT algorithm and data presentation.
In this paper, after describing the system specifications and
architecture, we present the results of the preliminary tests, which have
been carried out both in the laboratory and on the Storage Ring.
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| PT16 | A High Dynamic Range Beam Position Measurement System for ELSA-2 | linac, diagnostics, instrumentation | 205 | ||
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New beamlines are presently under construction for ELSA, a 20 MeV
electron linac located at Bruyères-le-Châtel. These lines need a beam
position measurement system filling the following requirements: small
footprint, wide dynamic range, single-bunch/multi-bunch capability,
simple design. We designed a compact 4-stripline sensor and an
electronic treatment chain based on logarithmic amplifiers. This paper
presents the design, cold and hot test results.
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| PT20 | A New Wide Band Wall Current Monitor | diagnostics, instrumentation, CTF3 | 216 | ||
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Wall current monitors (WCM) are commonly used to observe the time profile
of particle beams. In CTF3, a test facility for the future CERN Linear
Collider CLIC, high current electron beams of 1.5 μs pulse length are
bunched at 3 GHz and accelerated in a Linac working in fully loaded mode,
for which a detailed knowledge of the time structure along the pulse is
mandatory. The WCM design is based on an earlier version developed for
CTF2, a previous phase of the test facility, in which the beam duration
was only 16 ns. Due to the longer pulse width the low frequency cut-off
must be lowered to 10 kHz while the high frequency cut-off must remain at
10 GHz. The new WCM therefore has two outputs: a direct one for which an
increase of the inductance results in a 250 kHz to 10 GHz bandwidth while
the second one, using an active integrator compensating the residual
droop, provides a 10 kHz to 300 MHz bandwidth. The new WCM has been
installed in CTF2 late 2002 in order to test its high frequency
capabilities prior to its use in CTF3. Design considerations and first
results are presented.
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| PT22 | Measurement of the longitudinal phase space at the Photo Injector Test Facility at DESY Zeuthen | diagnostics, longitudinal-dynamics | 222 | ||
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The photo injector test facility at DESY Zeuthen (PITZ) has been
developed with the aim to deliver low emittance electron beams and study
its characteristics for future applications at free electron lasers and
linear accelerators. The energy of the electron beam varies in the range
between 4 and 5 MeV. One of the important properties of the delivered
beam is the longitudinal phase space of the electron beam. Measurements
of the momentum distributions show a small energy spread. The principle
of the measurement of the bunch length will be discussed, time
resolutions will be shown and preliminary results will be given. The
design to measure the correlation between momentum and time distribution
of the electron bunch will be shown with calculated resolutions.
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| PT24 | Development of a Bunch-Length Monitor with Sub-Picosecond Time Resolution and Single-Shot Capability
Funding: SNF (Schweizer National Fonds) |
diagnostics, instrumentation, linac, bunching, SLS | 228 | ||
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A bunch-length monitor with single-shot capability is under development
at the 100 MeV pre-injector LINAC of the Swiss Light Source (SLS). It is
based on the electro-optical effect in a ZnTe crystal induced by coherent
transition radiation (CTR). A spatial autocorrelation of the CTR in the
EO-crystal rotates the polarisation of a mode-locked Nd:YAG laser to
produce an image on an array detector representing the Fourier components
of the CTR spectrum. Up to now a theoretical model for the emission of
transition radiation has been developed in order to design optics
allowing efficient transport of the CTR onto the EO-crystal. The
frequency dependency of the CTR due to the finite size of the target
screen has been measured in the sub-THz regime at the SLS Linac. The
results strongly support the theoretical descriptions of the radiation
source. By expanding the intensity pattern in higher-order
Laguerre-Gaussian modes, the transmission through the optical transfer
system is calculated.
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| PT25 | Fast Tune Measurement System for the ELETTRA Booster | booster, diagnostics, instrumentation, storage-ring | 231 | ||
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Since several years, the Diagnostic Group at Laboratori Nazionali di
Legnaro (LNL) has been designing Fast Faraday Cups (FFC) to be used on
their Heavy Ion Accelerators; latest developments in this field include a
stripline FFC, jointly developed with SNS, Oak Ridge. A collaborative
partnership has been set-up between LNL and ELETTRA Laboratory to fully
characterize new FFCs, using as electron source the ELETTRA 1 GeV Linac.
Two FFCs, the stripline FFC, built at SNS, and a coaxial FFC, made at
LNL, have been installed at ELETTRA who provided the wideband data
acquisition and the remote control of the measurement. The first
measurements carried out using 1 GHz oscilloscope allowed the proper
set-up of remote control and a low jitter triggering. Wideband
measurements were performed with a sampling scope equipped with 50 GHz
head whereas the bandwidth of the stripline FFC is in the order of 10 GHz.
A complete set of tests has been carried both on the coaxial FFC and on
the stripline FFC. Thanks to the information provided by these wideband
measurements, the Linac working point has been further optimized as well
as the injection process into the ELETTRA SR.
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