| Paper | Title | Other Keywords | Page | ||
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| IT01 | Review Of Diagnostics For Next Generation Linear Accelerators | diagnostics, linear-collider | 1 | ||
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New electron linac designs incorporate substantial advances in critical
beam parameters such as beam loading and bunch length and will require
new levels of performance in stability and phase space control. In the
coming decade, e- (and e+) linacs will be built for a high power linear
collider (TESLA, CLIC, JLC/NLC), for fourth generation X-ray sources
(TESLA FEL, LCLS, Spring 8 FEL) and for basic accelerator research and
development (Orion). Each project assumes significant instrumentation
performance advances across a wide front.
This review will focus on basic diagnostics for beam position and phase
space monitoring. Research and development efforts aimed at high precision
multi-bunch beam position monitors, transverse and longitudinal profile
monitors and timing systems will be described.
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| IT02 | Instrumentation And Diagnostics Using Schottky Signals | diagnostics, incoherent-effects | 6 | ||
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Schottky signal measurements are a widely used tool for the determination
of longitudinal and transverse dynamical properties of hadron beams in
circular accelerators and storage rings. When applied to coasting beams,
it is possible to deduce properties as the momentum distribution. the
Qx,y-values and the average betatron amplitudes. Scientific
applications have been developed in the past few years, as well, namely
nuclear Schottky mass spectrometry and lifetime measurements. Schottky
signals from a coasting beam are random signals which appear at every
revolution harmonic and the respective betatron sidebands. Their
interpretation is more or less straightforward unless the signal is
perturbed by collective effects in the case of high phase space density.
Schottky signals from bunched beams reveal the synchrotron oscillation
frequency, from which the effective rf voltage seen by the beam can be
deduced. The detection devices can be broad-band or narrowband. The
frequency range is usually in the range between a few hundred kHz up to
about 150 MHz. In connection with stochastic cooling, Schottky signals
are used at frequencies up to 8 GHz. Narrow-band devices are needed if
signal-to-noise problems arise, e.g. in the case of antiproton beams.
Heavy ion beams require less effort, it is relatively easy to detect
single circulating highly charged ions.
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| IT03 | Diagnostics and Instrumentation for FEL | diagnostics, free-electron-laser | 11 | ||
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Free Electron Laser are coherent sources of radiation based on the
interaction of a relativistic electron beam in an undulator field.
According to the energy of the accelerator, they presently cover a wide
spectral range, from the infra-red to the VUV. FELs combine the
diagnostics of typical laser systems (for the measurement of spectral and
temporal characteristics, the transverse mode pattern, the polarisation)
and the diagnostics of relativistic electron beams. The electron beam is
characterised in order to evaluate and control the FEL performances, but
also in order to measure the effect of the FEL on the electron beam. The
FEL characteristics are monitored with various types of detectors,
depending mainly on the spectral range. Diagnostics for Linac based Infra
Red FELs and storage ring FELs in the UV-VUV will be described.
Particular instrumentation, required for FEL operation, such as the
optical resonator, possible diagnostics inside the undulator will also be
analysed.
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| IT04 | Review of Emittance and Stability Monitoring Using Synchrotron Radiation Monitors | diagnostics, emittance, synchrotron-radiation, synchrotron | 16 | ||
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Different techniques of emittance and stability monitoring using bend
magnet and undulator radiation will be reviewed. Besides imaging methods
for emittance monitoring , the problem of XBPM's used for the measurement
of the centre of mass position of the undulator beams will be treated in
detail. The key feature of these monitors is a careful electron optical
design to take account of gap dependent changes of the shape and photon
energy of the undulator beam as well as spurious signals from dipoles and
high heat load. The reason for the fact that these monitors work well on
low energy machines like BESSY II but often fail due in high energy
machines will be demonstrated by experimental results obtained on
different types of BESSY II insertion devices such as undulators,
wavelength shifters, multipole wigglers and electromagnetic undulators.
Experimental results of global and local orbit monitoring and a proof of
principle of a XBPM-based local feedback will be shown.
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| IT05 | Results with LHC Beam Instrumentation Prototypes | diagnostics, collider, LHC, storage-ring | 21 | ||
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The beam instrumentation foreseen to provide the
necessary diagnostics in the transfer lines and in the main
rings of the LHC was conceived in the past years. The
requirements expected from the different systems are now
being closely analyzed and specified. In a few cases, tests
of prototypes have already been performed, profiting from
the facilities offered by existing machines.
The beam position measurement system had to be
tackled first, as the pick-ups had to be integrated into the
cryogenic part of the machine. Over the last two years
other topics started to be experimentally investigated in
order to define the best way to meet the requirements for
the LHC era. Amongst these different studies are
luminosity monitoring devices, various instruments for the
measurement of the transverse beam distributions, the use
of head-tail sampling to measure the beam chromaticity
and quadrupole gradient modulation to derive the local
amplitude of the lattice function.
The paper discusses the results of these tests.
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| IT06 | Measurement of Small Transverse Beam Size Using Interferometry | diagnostics, emittance, brillance | 26 | ||
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The principle of measurement of the profile or size of small objects
through the spatial coherency of the light is known as the van
Cittert-Zernike theorem. We developed the SR interferometer
(interferometer for synchrotron radiation) to measure the spatial
coherency of the visible region of the SR beam, and we demonstrated that
this method is able to measure the beam profile and size. Since the small
electron beam emits a SR beam which has a good spatial coherency, this
method is suitable for measuring a small beam size. In this paper, the
basic theory for the measurement of the profile or size of a small beam
via the spatial coherency of the light, a design of the SR
interferometer, and the results of beam profile measurement, examples of
small beam size measurements and recent improvements are described.
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| IT07 | Accelerator Physics Experiments with Beam Loss Monitors at BESSY | diagnostics, beam-losses, BESSY | 31 | ||
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The extended use of beam loss monitoring has led to a better
understanding of the linear and non-linear physics involved in the single
and multiple particle dynamics at BESSY. This knowledge has been used for
improving the performance of the light source in terms of lifetime, beam
stability, and stability of the energy.
The key to these experiments are loss monitors placed at strategic
locations of the ring with high sensitivity to Touschek or Coulomb
scattered particles.
Coulomb-scattering depends strongly on the transverse dynamics which is
determined by the magnetic guiding fields. Losses occur primarily at the
vertical aperture restrictions imposed by the flat insertion device
vacuum chambers. Tune scan measurements clearly show resonances produced
by the lattice magnets and by some of the insertion devices.
Touschek scattering depends on the 3-dimensional electron density and the
spins of the colliding particles. In transfer function type experiments
these dependencies have been used to observe the effect of resonant
transverse and longitudinal beam excitations. Loss monitors allow to
detect excited head-tail and higher longitudinal modes which are
invisible in the center of mass motion. Another application is the
detection of the resonant destruction of the spin polarization of the
ensemble of electrons. This is used routinely in order to determine the
beam energy with high accuracy.
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| IT08 | Breaking New Ground with High Resolution Turn-By-Turn BPMs at the ESRF | diagnostics, ESRF, pick-up | 36 | ||
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This High-Resolution, Turn-by-Turn BPM system is a low-cost extension to
the existing BPM system, based on the RF-multiplexing concept, used for
slow Closed-Orbit measurements. With this extension Beam Position
measurements in both planes, at all (224) BPMs in the 844 m ESRF Storage
Ring, for up to 2048 Orbit Turns with 1 μm resolution are performed.
The data acquisition is synchronised to a single, flat 1 μs, transverse
deflection kick to the 1μs beamfill in the 2.8μs revolution period.
The high quality of this synchronisation, together with the good
reproducibility of the deflection kick and the overall stability of the
Closed Orbit beam allows to repeat the kick and acquisition in many
cycles. The subsequent averaging of the data obtained in these cycles
yields the 1um resolution.
The latter allows lattice measurements with high precision such as the
localisation of very small focussing errors and modulation in Beta values
and phase advances. It also finds an unique application to measure,
model, and correct the (H to V) Betratron coupling which recently showed
successfully the reduction of coupling and vertical emittance below
respectively 0.3% and 12picometer×rad. This method takes full
benefit from 64 BPM stations situated around 32 straight-sections (no
focussing elements) of 6m length allowing the phase-space measurements in
their centers.
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| IT09 | Overview of RHIC Beam Instrumentation and First Experience from Operation
Work performed under the auspices of the U.S. Department of Energy |
diagnostics, storage-ring, RHIC | 41 | ||
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A summary of the beam instrumentation tools in place during the year 2000
commissioning run is given including the technical layout and the
appearance on the user level, here mainly the RHIC control room.
Experience from rst usage is reported as well as the lessons we have
learned during RHIC operation so far. Upgrades and changes compared to
the year 2000 systems are outlined. Described tools include beam position
monitors (BPM), ionization prole monitors (IPM), beam loss monitors
(BLM), bunch current measurements, luminosity monitors, tune meters and
Schottky monitors.
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| IT10 | 6-D Electron Beam Characterisation Using Optical Transition Radiation and Coherent Diffraction Radiation | diagnostics, emittance, linear-collider | 46 | ||
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The development of non-intercepting diagnostics for high charge density
and high energy electron beams is one of the main challenge of beam
instrumentation.
Diffraction Radiation based diagnostics, being non-intercepting, are
among the possible candidates for the measurements of beam properties for
the new generation linacs.
At the 1 GeV Sincrotrone Trieste linac, we are performing the first
measurements of beam transverse parameters using Diffraction Radiation
emitted by the electron beam passing through a 1 mm slit opened on a
screen made of aluminium deposited on a silicon substrate.
The analysis of the angular distribution of the Diffraction Radiation for
a given wavelength, slit aperture and beam energy gives information about
the beam size and its angular divergence.
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| IT11 | Possible Spin-Offs from LHC Physics Experiments for Beam Instrumentation | diagnostics, storage-ring, LHC, collider | 51 | ||
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This paper aims to introduce some of the new
technology and materials used in the construction of the
LHC physics experiments into the domain of the beam
instrumentalist. The development of radiation hard fibre-optic
technology, for example, can equally well be
applied to beam instrumentation systems for the direct
transmission of analogue or digital signals from high to
low radiation environments. Many electronics techniques
such as a system developed for the fast integration of
photomultiplier signals could also prove very useful in
the construction of new beam diagnostic instruments for
bunch-to-bunch measurements. Other topics covered will
include a fast beam synchronous timing system based on
laser technology and a look at pixel detectors as a
possible replacement for CCD cameras in imaging
applications.
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| IT12 | Investigations of Longitudinal Charge Distribution in Very Short Electron-Bunches | diagnostics, emittance, linear-collider | 56 | ||
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Electro-optical-sampling is a powerful technique to measure
the longitudinal charge distribution of very short electron
bunches. The electrical field moving with the bunch
induces an optical an-isotropy in a ZnTe crystal which is
probed by a polarized laser pulse. Two measurement principles
are possible. In the first one a short laser pulse of
lengths <50 fs is used directly to scan the time varying
optical properties of the crystal. In the second method the
laser pulse is frequency chirped and the temporal information
is encoded into the time ordered frequency spectrum,
which can be recovered by an optical grating and a CCD
camera.
A resolution in the 100 fs regime can also be achieved
with longitudinal phase space tomography. Acceleration
on the slope of the rf wave at different phases and measurements
of the energy profiles are sufficient for a reconstruction
algorithm based on maximum entropy methods.
The longitudinal phase space distribution can be obtained
without artifacts due to the limited angular range of the
projections.
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| CT01 | BPM Read-Out Electronics Based on the Broadband AM/PM Normalization Schema | diagnostics, pick-up, closed-orbit | 63 | ||
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Recently developed circuit modules, used for the processing of position
signals of electrostatic (“button”-type) pickups are presented. The
concept is based on the broadband (“monopulse”) AM/PM normalisation
technique. The short integration time (≈ 10 ns) makes this
read-out electronics suitable for single-bunch position measurements
nearby interaction areas and in linear accelerators. Details on circuit
design and technology, as well as the practical realization are shown.
The results discussed include beam position and orbit measurements made
with a set of 40 units at the FEL-undulator sections of the TESLA Test
Facility (TTF) linac.
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| CT02 | First Commissioning Results of the ELETTRA Transverse Multi-Bunch Feedback | diagnostics, feedback, ELETTRA | 66 | ||
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A wide-band bunch-by-bunch Transverse Multi-Bunch Feedback, developed in
collaboration with the Swiss Light Source (SLS), has been installed at
ELETTRA. After a description of the main hardware/software components,
the first commissioning results and the present status of the system are
given.
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| CT03 | Performance of the Digital BPM System for the Swiss Light Source | diagnostics, pick-up, PSI, closed-orbit | 69 | ||
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The accelerator complex of the Swiss Light Source (SLS) is presently
under commissioning at the Paul Scherrer Institute (PSI) in Villigen,
Switzerland. The newly developed digital beam position monitor (DBPM)
system has been successfully used to determine beam positions in the
pre-injector LINAC, the transfer lines, the booster synchrotron and the
storage ring. Instant and free selection of operation modes through the
EPICS-based SLS control system allows to choose between single turn,
turn-by-turn and closed orbit measurements. The operational experience
and performance of the DBPM system is presented, based on measurements,
taken during SLS commissioning. A monitoring system (POMS), which
measures the horizontal and vertical mechanical positions of each BPM
block in reference to the adjacent quadrupole magnets has been installed
and first results, indicating transverse movements of the BPM blocks as
a function of current in the storage ring will be presented.
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| CT04 | Fibre Optical Radiation Sensing System for TESLA | diagnostics, beam-losses, linear-collider, fibre-optics, TESLA, TTF | 73 | ||
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High energy accelerators generate ionising radiation along the beam-line
and at target places. This radiation is related to beam losses or dark
currents. The in-situ measurement of this ionising dose that is
distributed over long distances or large areas requires a new monitor
system. This paper presents first results and the concept of such a
monitor system at the Tesla Test Facility.
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| CT05 | Beam-Profile Instrumentation for a Beam-Halo Measurement: Overall Description, Operation, and Beam Data
Work supported by the US Department of Energy |
diagnostics, emittance | 76 | ||
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The halo experiment presently being conducted at the Low Energy
Demonstration Accelerator (LEDA) at Los Alamos National Laboratory
(LANL) has specific instruments that acquire horizontally and vertically
projected particle-density beam distributions out to greater than 105:1
dynamic range. We measure the core of the distributions using
traditional wire scanners, and the tails of the distribution using
water-cooled graphite scraping devices. The wire scanner and halo
scrapers are mounted on the same moving frame whose location is
controlled with stepper motors. A sequence within the Experimental
Physics and Industrial Control System (EPICS) software communicates with
a National Instrument LabVIEW virtual instrument to control the movement
and location of the scanner/scraper assembly. Secondary electrons from
the wire scanner 33 μm carbon wire and protons impinging on the
scraper are both detected with a lossy-integrator electronic circuit.
Algorithms implemented within EPICS and in Research Systems
Interactive Data Language (IDL) subroutines analyse and plot the
acquired distributions. This paper describes the beam profile
instrument, describes our experience with its operation, compares
acquired profile data with simulations, and discusses various beam
profile phenomenon specific to the halo experiment.
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| CT06 | The Measurement of Q' And Q'' in the CERN-SPS by Head-Tail Phase Shift Analysis | diagnostics, chromatic-effects, SPS | 79 | ||
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A so-called "Head-Tail" chromaticity measurement system has recently
been installed in the CERN-SPS, which allows the chromaticity (Q’) to be
calculated from several hundred turns of data after transverse
excitation. The measurement relies on the periodic dephasing and
rephasing that occurs between the head and tail of a single bunch for
non-zero chromaticity. By measuring the turnby-turn position data from
two longitudinal positions in a bunch it is possible to extract the
relative dephasing of the head and the tail, and so to determine the
chromaticity. In addition, by changing the orbit of the circulating beam
this technique allows the variation of chromaticity with radial position
(Q’’) to be measured with a much higher resolution than is currently
possible using RF modulation. This paper describes this "Head-Tail"
measurement technique and discusses some recent results obtained using
prototype LHC beam (25 ns spacing) in the CERN-SPS.
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| CT07 | Excitation of Large Transverse Beam Oscillations without Emittance Blow-Up Using the "AC-Dipole" Principle | diagnostics, emittance, SPS | 82 | ||
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The so-called "AC-Dipole" principle allows the excitation of transverse
oscillations to large (several σ) excursions without emittance
blow-up. The idea was originally proposed and tested at BNL for
resonance crossing with polarized beams, using an orbit corrector dipole
with an excitation frequency close to the betatron tune, hence
"AC-Dipole". This method of beam excitation has several potential
applications in the LHC, such as phase advance and β-measurements,
dynamic aperture studies and the investigation of resonance strengths.
The technique was recently tested in the CERN-SPS using the transverse
damper as an "AC-Dipole" providing the fixed frequency excitation.
results from this experiment are presented, along with an explanation of
the underlying principle.
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| CT08 | Measuring Beta-Functions with K-Modulation | diagnostics, emittance, SPS | 85 | ||
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The precise measurement of the local value of the beta-function at the
place of a beam size monitor is necessary for the precise determination
of the beam emittance. We developed a new method for the measurement of
the beta-function by using of continuous square-wave modulation of the
force of the quadrupole and by continuous tune tracking. Measurements
were performed at LEP in order to evaluate the precision that can be
achieved with this method in the LHC. The paper describes the method and
discusses in details the results obtained at LEP for colliding and
non-colliding beams.
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| CT09 | X-Ray Interference Methods of Electron Beam Diagnostics | diagnostics, emittance, synchrotron-radiation, ESRF | 88 | ||
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Electron beam diagnostics methods based interference and diffraction of
synchrotron radiation (SR) in hard X-ray range will be discussed. Two
simple optical schemes providing X-ray interference patterns highly
sensitive to transverse size of the emitting electron beam, will be
considered. For each scheme, the visibility of fringes in the pattern
depends on transverse size of the electron beam. However, the pattern is
also determined by the scheme geometry, shape and material of diffracting
bodies. Therefore, for correct interpretation of the experimental
results, high-accuracy computation of SR emission and propagation in the
framework of physical optics should be used. Examples of practical
measurements and processing of the results are presented.
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| CT10 | Beam Charge Asymmetry Monitors for Low Intensity Continuous Electron Beam
Work supported the Southeastern Universities Research Association (SURA) which operates the Thomas Jefferson National Accelerator Facility (JLAB) for the U.S. Department of Energy under contract DE-AC05-84ER40150 |
diagnostics, JLAB, synchrotron-radiation | 91 | ||
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Experimental Hall B at Jefferson Lab (JLAB) typically operates
with CW electron beam currents in the range of 1-10 nA. This
low beam current coupled with a 30 Hz flip rate of the beam
helicity required the development of new
devices to measure and monitor the beam charge asymmetry.
We have developed four independent devices with sufficient
bandwidth for readout at 30 Hz rate: a synchrotron
light monitor (SLM), two backward optical transition radiation
monitors (OTR) and a Faraday Cup. We present the
results from the successful operation of these devices during
the fall 2000 physics program. The reliability and the
bandwidth of the devices allowed the control of the current
asymmetry at the source laser by means of a feedback loop.
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| CT11 | New Development of a Radiation-Hard Polycrystalline CDTE Detector for LHC Luminosity Monitoring | diagnostics, collider, storage-ring, LHC, luminosity | 94 | ||
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Detectors presently considered for monitoring and
control of the LHC luminosity will sample the
hadronic/electromagnetic showers produced by neutrons
and photons in copper absorbers designed to protect the
superconducting magnets from quenching. At this
location the detectors will have to withstand extreme
radiation levels and their long term operation will have to
be assured without requiring human intervention. For this
application we have successfully tested thick
poly-crystalline-CdTe detectors. The paper summarizes
the results obtained on rise-times, sensitivity and
resistance to neutron irradiation up to a dose of
1015/cm2.
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| PS01 | Real-Time Tune Measurements on the CERN Antiproton Decelerator | diagnostics, CERN-AD, transverse-dynamics | 99 | ||
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A novel system for real-time tune measurement during deceleration of a
low-intensity particle beam is presented. The CERN Antiproton Decelerator
decelerates low intensity (2×107) antiproton beams from 3.5 GeV/c
to 100 MeV/c. Because of the eddy-currents in the magnets, a
tune-measurement during a pause in the deceleration would not be
representative. One must thus be able to measure the tune in real time
during the deceleration. The low intensity of the antiproton beam
prevents the use of standard Schottky techniques, and swept Beam Transfer
Function (BTF) measurements are too slow. A system was therefore
developed which uses an M-shaped power spectrum, exciting the beam in a
band around the expected frequency of a betatron side-band. Excitation at
the betatron frequency, where beam response is highest, is thus minimized
and measurements of BTF, and therefore the tune, can be made with much
reduced emittance blowup.
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| PS02 | Bench Test of a Residual Gas Ionization Profile Monitor (Rgipm)
Work supported by U.S. Department of Energy |
diagnostics, emittance, brillance, LANL | 102 | ||
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An RGIPM has been designed, constructed and bench tested to verify that
all components are functioning properly and that the desired resolution
of about 50μm× rms can be achieved. This paper will describe some system
details and it will compare observed results to detailed numerical
calculations of expected detector response.
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| PS03 | Optical Bunch-By-Bunch Diagnostic System in KEK-PF | diagnostics, KEK-PF, single-bunch | 105 | ||
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An optical bunch-by-bunch beam diagnostic system, which can detect
oscillations of individual bunches in a multibunch operation, has been
developed. The system is composed of a high-speed light shutter and an
optical beamoscillation detector. The shutter that consists of a pockels
cell and polarizers can be opened or closed in a bunch spacing time (2ns
in KEK-PF) and it can select a light pulse corresponding to a certain
bunch in a bunch train. The beam oscillation detector can detect
oscillations of the pickedout bunch with a spectral analysis method. The
diagnostic system has been installed in KEK-PF Beamline-21, and observed
vertical oscillation of individual bunches due to an instability in the
multi-bunch operation.
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| PS04 | Design of a Magnetic Quadrupole Pick-Up for the CERN PS | diagnostics, pick-up, CERN-PS, emittance | 108 | ||
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A quadrupole pick-up is sensitive to the quantity σ2x -
σ2y, where σx and σy are the horizontal and vertical
r.m.s. beam sizes. Since it is a non-invasive device, it is potentially
very useful for matching and emittance measurements. A magnetic
quadrupole pick-up has been developed for the CERN PS. By coupling to the
radial component of the magnetic field around the beam, it was possible
to eliminate the common-mode problem, which is usually a limiting factor
in the use of quadrupole pick-ups. This paper presents the final pick-up
design, which is the result of a series of simulations and test
prototypes. The performance of the pick-up and its associated electronics
is discussed. Preliminary results from the two pick-ups recently
installed in the PS machine are also presented.
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| PS05 | Measurement of the Time-Structure of the 72 MeV Proton Beam in the PSI Injector-2 Cyclotron | diagnostics, PSI, emittance | 111 | ||
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The time-structure monitor at the last turn of the 72MeV Injector-2
cyclotron has been improved in order to meet the stringent
time-resolution requirement imposed by the short bunch length. Protons
scattered by a thin carbon-fibre target pass through a first
scintillator-photomultiplier detector and are stopped in a second one.
The longitudinal bunch shape is given by the distribution of arrival
times measured with respect to the 50 MHz reference signal from the
acceleration cavities. From a coincidence measurement, the time
resolution of the detectors has been determined to be 51 ps and 31 ps
fwhm. Longitudinal and horizontal bunch shapes have been measured at beam
currents from 25μA to 1700μA. Approximately circular bunches were
observed with diameter increasing with current. The shortest observed
proton bunch length was 38 ps fwhm.
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| PS06 | Laser Profile Measurements of an H-Beam | diagnostics, SNS, emittance | 114 | ||
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A non-intercepting beam profile monitor for H--beams
is being developed at Brookhaven National Lab.
An H- ion has a first ionization potential of 0.75eV.
Electrons can be removed from an H--beam by passing
light from a near-infrared laser through it. Experiments
have been performed on the BNL linac to measure the
transverse profile of a 750keV beam by using a Nd:YAG
laser to photoneutralize narrow slices of the beam. The
laser beam is scanned across the ion beam neutralizing the
portion of the beam struck by the laser. The electrons are
removed from the ion beam and the beam current notch is
measured.
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| PS07 | New Schottky-Pickup for COSY-Jülich | diagnostics, COSY, pick-up | 117 | ||
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A new Schottky-pickup for the Cooler Synchrotron COSY at the
Forschungszentrum Jlich was developed, tested and installed. The new
pickup with four diagonally arranged plates replaces the two 1 m long
Schottky-pickups used until now in COSY. The previous ones were removed
mainly to gain space for new installations (e.g. rf-cavity, experimental
devices), but also to increase the horizontal aperture. The available
space for the new pickup is only 0.8 m. The pickup plates can be combined
by means of relays to measure either in the horizontal or in the vertical
plane. The pickup can also be used either as a sensitive broadband beam
position monitor or as a tuneable narrowband pickup for Schottky-noise
analysis with ultahigh sensitivity. A new method for resonant tuning of
the Schottky-pickups for transversal measurements was developed. The
differentially excited resonant circuitry enhances the sensitivity by
about a factor of 30. The pickups are also used for dynamical tune
measurements (tune meter) in the acceleration ramp.
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| PS08 | Current Transformers for GSI's KeV/u to GeV/u Ion Beams - An Overview | diagnostics, GSI, linac, isotope-production | 120 | ||
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At GSI's accelerator facilities ion beam intensities usually are observed
and measured with various types of current transformers (CT), matched to
the special requirements at their location in the machines.
In the universal linear accelerator (UNILAC), and the high charge state
injector (HLI) as well, active transformers with 2nd-order feedback are
used, while passive pulse CTs and two DC-CTs based on the magnetic
modulator principle are implemented in the heavy ion synchrotron (SIS)
and the experimental storage ring (ESR). In the high energy beam transfer
lines (HEBT) the particle bunch extraction/reinjection is monitored with
resonant charge-integrating types.
Since more than 10 years number and significance of beam current
transformers for operating GSI's accelerators have grown constantly. Due
to increased beam intensities following the last UNILAC upgrade,
transmission monitoring and beam loss supervision with CTs have become
the main tools for machine protection and radiation security purposes.
All CTs have been constructed and developed at GSI, since no commercial
products were available, when solutions were needed.
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| PS09 | Transverse Beam Profile Measurements Using Optical Methods | diagnostics, GSI, linac, emittance | 123 | ||
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Two different systems are currently under development at GSI's heavy ion
facility to measure transverse beam profiles using optical emitters. At
the GSI-LINAC for energies up to 15 MeV/u residual gas fluorescence is
investigated for pulsed high current beams. The fluorescence of N2 is
monitored by an image intensified CCD camera. For all ion species with
energies above 50 MeV/u slowly extracted from the synchrotron SIS a
classical viewing screen system is used. Three different target materials
have been investigated and their behavior concerning efficiency,
saturation and timing performance is evaluated. Both systems (will) use
CCD cameras with a digital read out using the IEEE 1394 standard.
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| PS10 | Control and Data Analysis for Emittance Measuring Devices | diagnostics, controls, GSI, emittance | 126 | ||
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Due to the wide range of heavy ion beam intensities and energies in the
GSI linac and the associated transfer channel to the synchrotron, several
different types of emittance measurement systems have been established.
Many common devices such as slit/grid or dipole-sweep systems are
integrated into the GSI control system. Other systems like the single
shot pepper pot method using CCD-cameras or stand-alone slit/grid set-ups
are connected to personal computers. An overview is given about the
various systems and their software integration. Main interest is directed
on the software development for emittance front-end control and data
analysis such as evaluation algorithms or graphical presentation of the
results. In addition, special features for improved usability of the
software such as data export, project databases and automatic report
generation will be presented. An outlook on a unified evaluation
procedure for all different types of emittance measurement is given.
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| PS11 | Test of Different Beam Loss Detectors at the GSI Heavy Ion Synchrotron | diagnostics, beam-losses, GSI, synchrotron | 129 | ||
|
For the sensitive process of slow extraction from a synchrotron
a reliable control of the beam losses is needed.
We have tested several types of particle detectors mounted
at the extraction path of the SIS: A BF-tube for pure neutron
detection, a liquid and a plastic scintillator detecting
neutrons, gammas and charged particles and an Argon filled
ionization chamber mainly sensitive to charged particles.
While the count rate is quite different, the time evolution of
all detector signals during the spill are similar, but the plastic
scintillator has the highest dynamic range. This type is
going to be used for beam alignment.
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| PS12 | Source Imaging with Compound Refractive Lenses | diagnostics | 132 | ||
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| PS13 | A Zone Plate Based Beam Monitor for the Swiss Light Source | diagnostics, PSI, emittance | 133 | ||
|
At the Swiss Light Source, a source imaging set-up is planned on a
dedicated dipole magnet beam-line. A transmission Fresnel Zone Plate will
be used to generate a demagnified image of the source at a photon energy
in the 1.8 keV range. The image will be acquired by scanning a pinhole in
the image plane. A diffraction limited spatial resolution of
approximately 2 microns can be anticipated. The concept has the advantage
of having no components operated in reflection, and no components inside
the frontend.
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| PS14 | Microwave Pickups for the Observation of Multi GHz Signals Induced by the ESRF Storage Ring Electron Bunches | diagnostics, pick-up, ESRF, storage-ring, emittance | 136 | ||
|
The length of the bunches stored in ESRF lies in the 30 ps to 120 ps
range (FWHM). The observation of single bunch phenomena like transverse
or longitudinal oscillations or bunch length variation requires the
acquisition and analysis of signals at frequencies higher than 10 GHz. A
set of microwave cavity pick ups operating at 10 GHz and 16 GHz together
with the appropriate electronics has been implemented on the ESRF storage
ring; it detects the wall currents on the vacuum chamber due to the
electron beams circulation. We describe the design of these cavities,
give the result and analysis of measurements performed with the pick ups
and indicate how we plan to use these devices as beam diagnostics
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| PS15 | A New Wirescanner Control Unit | diagnostics, controls, DESY, emittance | 139 | ||
|
Wires scanners are standard instruments for beam size measurements in
storage rings: A wire is crossing the beam at a given speed and the
secondary emission current of the wire and/or the photomultiplier signals
produced from Bremsstrahlung or particles scattered at the wire are
recorded together with the wire positions. The control unit described
here is based on a previous CERN design. It now has additional features:
Triggered fast scans (1m/s) with a trigger uncertainty below ±30μs
(mechanics + electronics) used at the TTF Linac and at the proton
synchrotron DESY III, Slow scans (e.g. 50μm/s) for the TTF Linac,
Positioning of the wire within ±3μm for tail scans at the storage
rings PETRA and HERA, A 10.5MHz data acquisition rate for bunch-by-bunch
acquisitions in the accelerators at DESY. Another important design goal
was the compatibility with CERN scanners; it is foreseen to operate them
at LHC with the new control unit. First measurements with the new control
unit at TTF and HERA will be presented.
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| PS17 | Beam Size Measurement of the Spring-8 Storage Ring by Two-Dimensional Interferometer | diagnostics, synchrotron-radiation, SPring-8, emittance | 142 | ||
|
Two-dimensional interferometer using visible
synchrotron radiation was developed in order to measure
beam sizes at a source point in a bending magnet of the
SPring-8 storage ring. The theoretical background of this
method is described in the framework of wave-optics.
Assuming designed optics parameters, transverse
emittance was evaluated from measured beam size.
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| PS18 | Planned X-Ray Imaging of the Electron Beam at the SPRING-8 Diagnostics Beamline BL38B2 | diagnostics, synchrotron-radiation, SPring-8, emittance | 145 | ||
|
X-ray imaging observation of the electron beam is
planned at the SPring-8 storage ring diagnostics beamline
BL38B2 to evaluate small vertical emittance. The
resolution target is 1 micron of electron beam size (1s).
The synchrotron radiation from a dipole magnet source
will be imaged by a single phase zone plate.
Monochromatic X-ray with energy of 8keV will be
selected by a double crystal monochromator. The
magnification factor of the zoneplate is 0.27, and an X-ray
zooming tube will be used as a detector to compensate
for demagnification.
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| PS19 | Status of the Delta Synchrotron Light-Monitoring-System | diagnostics, DELTA, synchrotron-radiation, controls | 148 | ||
|
Synchrotron radiation sources like DELTA need an optical monitoring
system to measure the beam size at different points of the ring with high
resolution and accuracy. An investigation of the emittance of the storage
ring can also be done by these measurements.
Scope of this paper is the investigation of the resolution limit of the
different types of optical synchrotron light monitors at DELTA, a third
generation synchrotron radiation source. At first the normal synchrotron
light monitor is analysed. The minimum measurable electron beamsize at
DELTA is about 80μm. Emphasis is then put on a special synchrotron
light interferometer, developed for DELTA, which has been built up and
tested. This interferometer uses the same beamline and can measure
beamsizes down to about 8μm. So its resolution is about ten times
better and sufficient for the expected small vertical beamsizes at DELTA.
Measurements of the electron beamsize and emittance were done with both
(synchrotron light monitor and interferometer) at different energies.
The image processing system based on a PC Framegrabber generates a
gaussian fit to the images from different synchrotron light-monitors and
calculates the beamsizes and positions.
An investigation of possible reasons of beam movements will be appended,
because the theoretical values of the present optics are smaller than the
measured emittance.
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| PS20 | Beam Diagnostic for the Next Linear Collider | diagnostics, linear-collider, NLC | 151 | ||
|
The Next Linear Collider (NLC) is proposed to study
e+-e--collisions in the TeV energy region. The small beam spot size
at the interaction point of the NLC makes its luminosity sensitive to
beam jitter. A mechanism for aligning the beams to each other which acts
during the bunch-train crossing time has been proposed to maintain
luminosity in the presence of pulse-pulse beam jitter. We describe a
beam-beam deflection feedback system which responds quickly enough to
correct beam misalignments within the 265 ns long crossing time. The
components of this system allow for a novel beam diagnostic, beam-beam
deflection scans acquired in a single machine pulse.
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| PS21 | Diagnostics for the Photon Injector Test Facility in Desy Zeuthen | diagnostics, PITZ, free-electron-laser, linac, emittance | 154 | ||
|
A Photo Injector Test facility (PITZ) is under construction at
DESY-Zeuthen. The aim is to develop and operate an optimized photo
injector for future free electron lasers and linear accelerators. This
concerns especially minimal transverse emittances and proper
longitudinal phase space. The commissioning of the photo injector will
take place in summer 2001. In the rst phase the energy of the produced
electrons is about 5 MeV. A short description of the setup and beam
parameters are given. Optimization of an electron gun is only possible
based on an extended diagnostics system. The diagnostics system for the
analysis of the transversal and longitudinal phase space will be
described. It consists of a measurement system of the transversal
emittance, a TV-based image measurement system, a streakcamera
measurement facility, a spectrometer using a dipole magnet and further
detectors. Problems of the measurement of the longitudinal phase space
are discussed in detail.
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| PM01 | Position Monitoring of Accelerator Components as Magnets and Beam Position Monitors | diagnostics, DELTA, alignment, pick-up | 159 | ||
|
In third generation light sources a large amount of heat load from
synchrotron radiation must be dissipated from the vacuum chamber. The
synchrotron radiation hits the outer chamber wall and leads to a bending
of the vacuum chamber.
Due to the fact that very often beam position monitors are included into
the vacuum chamber, they start to move with increased heat load onto the
vacuum chamber.
An inexpensive and precise method to monitor this movement has been
tested at the Dortmunder Electron Test Accelerator (DELTA). Commercially
available Linear Variable Differential Transformers (LVDTs) have been
used.
In addition it was possible to demonstrate that due to the vacuum chamber
contact to quadrupole magnets the quadrupoles were moving with increasing
beam current leading to a significant orbit drift.
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| PM02 | Signal Processor for Spring8 Linac BPM | diagnostics, linac, pick-up, controls, SPring-8 | 162 | ||
|
A signal processor of the single shot BPM system consists of a
narrow-band BPF unit, a detector unit, a P/H circuit, an S/H IC and a
16-bit ADC. The BPF unit extracts a pure 2856MHz RF signal component from
a BPM and makes the pulse width longer than 100ns. The detector unit that
includes a demodulating logarithmic amplifier is used to detect an S-band
RF amplitude. A wide dynamic range of beam current has been achieved;
0.01 ~ 3.5nC for below 100ns input pulse width, or 0.06 ~ 20mA for above
100ns input pulse width. The maximum acquisition rate with a VME system
has been achieved up to 1kHz.
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| PM03 | Accuracy Of The LEP Spectrometer Beam Orbit Monitors | diagnostics, pick-up, closed-orbit, LEP, energy-calibration | 165 | ||
|
At the LEP e+/e- collider, a spectrometer is used to determine
the beam energy with a target accuracy of 10-4.
The spectrometer measures the lattice dipole bending angle
of the beam using six beam position monitors (BPMs).
The required calibration error imposes a BPM accuracy of
1 æm corresponding to a relative electrical signal variation
of 2×10-5. The operating parameters have been compared
with beam simulator results and non-linear BPM response
simulations. The relative beam current variations between
0.02 and 0.03 and position changes of 0.1mm during the
fills of last year lead to uncertainties in the orbit measurements
of well below 1μm. For accuracy tests absolute
beam currents were varied by a factor of three. The environment
magnetical field is introduced to correct orbit readings.
The BPM linearity and calibration was checked using
moveable supports and wire position sensors. The BPM
triplet quantity is used to determine the orbit position monitors
accuracy. The BPM triplet changed during the fills
between 1 and 2μm RMS, which indicates a single BPM
orbit determination accuracy between 1 and 1.5μm.
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| PM04 | Stripline Beam Position Monitors For "ELBE" | diagnostics, ELBE, pick-up, linac | 168 | ||
|
At the Forschungszentrum Rossendorf (FZR), the
superconducting electron linear accelerator ELBE is under
construction. It will deliver an electron beam with an
energy of up to 40 MeV at an average beam current of up
to 1mA. The accelerator uses standing wave DESY type
RF cavities operating at 1.3 GHz. A non-destructive
system for the measurement of the beam position at about
30 locations is needed. To obtain the required resolution
of 100μm, a system of stripline beam position monitors
(BPM) is under design.
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| PM05 | Functionality Enhancement of the Multiplexing BPM System in the Storage of SRRC | diagnostics, SRRC, pick-up, closed-orbit, synchrotron | 171 | ||
|
An extension of existing multiplex BPM electronics to provide capability
for turn-by-turn beam position and phase advance measurement is
implemented. The system can be configured as turn-by-turn beam position
measurement or phase advance and coupling measurement. For turn-by-turn
mode, the system performed four consecutive measurements of four BPM
buttons. Data acquisition is synchronize with beam excitation.
Turn-by-turn beam position is reconstructed by these four independent
measurements. This system was named as pseudo-turn-by-turn beam position
monitor system (PTTBPM). Resonance excitation of the stored beam and
adopting lock-in techniques can measure betatron phase and local
coupling. Design considerations of the system and preliminary beam test
results are presented in this report.
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| PM06 | The Low Gap BPM System at ELETTRA: Commissioning Results | diagnostics, ELETTRA, synchrotron, closed-orbit, pick-up | 174 | ||
|
Two Low Gap BPMs have been successfully installed
at ELETTRA and have now completed the commissioning
phase. The main purpose of these new devices is to
provide stable beam position measurement, at sub-micron
level, to monitor the stability of the light delivered to the
Users. The improvements with respect to the normal BPM
system have been obtained adopting both a new Low Gap
BPM sensor and a new non-multiplexed BPM detector,
the latter being developed in co-operation with the SLS
diagnostic group at the PSI. Beside the Closed Orbit
mode, thanks to the digitally selectable bandwidth, the
new BPM detector can be operated also in the Turn-by-Turn
mode and provide the position signal to feedback loops.
In this paper we first briefly review the system
architecture, describing its mechanical and electronic
parts. Then, we present the digital BPM detector set-up
used at ELETTRA and the associated firmware required
by the four-channel BPM detector to guarantee
performance over the full dynamic range. The BPMposition
monitoring system is also described and its
integration in the BPM system presented. Laboratory tests
confirmed sub-micron resolution at 10kHz data rate. A
series of beam based measurements have been performed
in order to test this system and to verify the improvement
in performance. The system is presently used in the
control room as a powerful beam quality monitor; its
extension to other Storage Ring straight sections is under
evaluation.
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| PM07 | Orbit Control at the Advanced Photon Source
Work supported by the US Department of Energy |
diagnostics, controls, closed-orbit, APS, pick-up | 177 | ||
|
The Advanced Photon Source (APS) began operation in 1995 with the
objective of providing ultra-stable high-brightness hard x-rays to its
user community. This paper will be a review of the instrumentation and
software presently in use for orbit stabilization. Broad-band and
narrow-band rf beam position monitors as well as x-ray beam position
monitors supporting bending magnet and insertion device source points are
used in an integrated system. Status and upgrade plans for the system
will be discussed.
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| PM08 | Advanced Photon Source RF Beam Position Monitor System Upgrade Design and Commissioning | diagnostics, controls, closed-orbit, APS, pick-up | 180 | ||
|
This paper describes the Advanced Photon Source (APS) storage ring
mono-pulse rf beam position monitor (BPM) system upgrade. The present rf
BPM system requires a large dead time of 400 ns between the measured
bunch and upstream bunch. The bunch pattern is also constrained by the
required target cluster of six bunches of 7 mA minimum necessary to
operate the receiver near the top end of the dynamic range. The upgrade
design objectives involve resolving bunches spaced as closely as 100 ns.
These design objectives require us to reduce receiver front-end losses
and reflections. An improved trigger scheme that minimizes systematic
errors is also required. The upgrade is in the final phases of
installation and commissioning at this time. The latest experimental and
commissioning data and results will be presented.
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| PM09 | Design of a Multi-Bunch BPM for the Next Linear Collider
Work supported by the US Department of Energy, contract DE-AC03-76SF00515 |
diagnostics, NLC, pick-up, linear-collider | 183 | ||
|
The Next Linear Collider (NLC) design requires
precise control of colliding trains of high-intensity
(1.4×1010 particles/bunch) and low-emittance beams.
High-resolution multi-bunch beam position monitors
(BPMs) are required to ensure uniformity across the
bunch trains with bunch spacing of 1.4ns. A high
bandwidth (~350 MHz) multi-bunch BPM has been
designed based on a custom-made stripline sum and
difference hybrid on a Teflon-based material. High
bandwidth RF couplers were included to allow injection
of a calibration tone. Three prototype BPMs were
fabricated at SLAC and tested in the Accelerator Test
Facility at KEK and in the PEP-II ring at SLAC. Tone
calibration data and single-bunch and multi-bunch beam
data were taken with high-speed (5Gsa/s) digitisers.
Offline analysis determined the de-convolution of
individual bunches in the multi-bunch mode by using the
measured single bunch response. The results of these
measurements are presented in this paper.
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| PM10 | A Logarithmic Processor for Beam Position Measurements Applied to a Transfer Line at CERN | diagnostics, pick-up, closed-orbit, beam-transport, controls | 186 | ||
|
The transfer line from the CERN proton synchrotron
(PS) to the super proton synchrotron (SPS) requires a new
beam position measurement system in view of the LHC.
In this line, the single passage of various beam types
(up to 7), induces signals with a global signal dynamics of
more than 100 dB and with a wide frequency spectral
distribution.
Logarithmic amplifiers, have been chosen as technical
solution for the challenges described above.
The paper describes the details of the adopted solutions
to make beam position measurements, with a resolution
down to few 10-4 of the full pickup aperture over more
than 50 dB of the total signal dynamics.
The reported performances has been measured on the
series production cards, already installed into the machine
and on one pickup in the transfer line.
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| PM11 | Injection Matching Studies Using Turn-By-Turn Beam Profile Measurements in the CERN PS | diagnostics, emittance, pick-up, injection, CERN-PS | 189 | ||
|
The very small emittance beam needed for the LHC requires that the
emittance blow-up in its injector machines must be kept to a minimum.
Mismatch upon the beam transfer from one machine to the next is a
potential source of such blow-up. The CERN PS ring is equipped with 3
Secondary Emission Grids (SEM-Grids) which are used for emittance
measurement at injection. One of these has been converted to a multi-turn
mode, in which several tens of consecutive beam passages can be observed.
This allows the study of mismatch between the PS-Booster and the PS. This
paper describes the instrument and experimental results obtained during
the last year.
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| PM12 | The SPS Individual Bunch Measurement System | diagnostics, pick-up, CERN-SPS, controls | 192 | ||
|
The Individual Bunch Measurement System (IBMS)
allows the intensity of each bunch in an LHC batch to be
the measured both in the PS to SPS transfer lines and in
the SPS ring itself. The method is based on measuring the
peak and valley of the analogue signal supplied by a Fast
Beam Current Transformer at a frequency of 40MHz. A
12 bit acquisition system is required to obtain a 1 %
resolution for the intensity range of 5×109 to 1.7×1011
protons per bunch, corresponding to the pilot and ultimate
LHC bunch intensities. The acquisition selection and
external trigger adjustment system is driven by the
200MHz RF, which is distributed using a single-mode
fibre-optic link. A local oscilloscope, controlled via a
GPIB interface, allows the remote adjustment of the
timing signals. The low-level software consists of a realtime
task and a communication server run on a VME
Power PC, which is accessed using a graphical user
interface. This paper describes the system as a whole and
presents some recent uses and results from the SPS run in
2000.
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| PM13 | Control Modules for Scintillation Counters in the SPS Experimental Areas | diagnostics, controls, beam-transport, CERN-SPS | 195 | ||
|
The hardware used in the SPS Experimental Areas to control the beam
instrumentation electronics and mechanics of the particle detectors is
based on CAMAC and NIM modules. The maintenance of this hardware now
presents very serious problems. The modules used to operate the
Experimental Areas are numerous and older than 20 years so many of them
cannot be repaired any more and CAMAC is no longer well supported by
industry. The fast evolution of technology and a better understanding of
the detectors allow a new equipment-oriented approach, which is more
favourable for maintenance purposes and presents fewer data handling
problems. VME and IP Modules were selected as standard components to
implement the new electronics to control and read out the particle
detectors. The first application implemented in this way concerns the
instrumentation for the Scintillation Counters (formerly referred to as
triggers). The fundamental options and the design features will be
presented.
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| PM14 | LHC Beam Loss Monitors | diagnostics, beam-losses, LHC, collider, simulation | 198 | ||
|
At the Large Hadron Collider (LHC) a beam loss
system will be installed for a continuous surveillance of
particle losses. These beam particles deposit their energy
in the super-conducting coils leading to temperature
increase, possible magnet quenches and damages.
Detailed simulations have shown that a set of six
detectors outside the cryostats of the quadrupole magnets
in the regular arc cells are needed to completely diagnose
the expected beam losses and hence protect the magnets.
To characterize the quench levels different loss rates
are identified. In order to cover all possible quench
scenarios the dynamic range of the beam loss monitors
has to be matched to the simulated loss rates. For that
purpose different detector systems (PIN-diodes and
ionization chambers) are compared.
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| PM15 | Sensitivity Studies with the SPS Rest Gas Profile Monitor | diagnostics, emittance, CERN-SPS | 201 | ||
|
During the SPS run in the year 2000 further test
measurements were performed with the rest gas monitor.
First, profiles of single circulating proton bunches were
measured and the bunch charge progressively reduced, in
order to determine the smallest bunch intensity which can
be scanned under the present operating conditions. The
image detector in this case was a CMOS camera.
Using a multi-anode strip photo-multiplier with fast
read-out electronics, the possibility to record profiles on a
single beam passage and on consecutive turns was also
investigated. This paper presents the results of these tests
and discusses the expected improvements for the
operation in 2001.
Moreover, the issue of micro channel plate ageing
effects was tackled and a calibration system based on
electron emission from a heating wire is proposed. The
gained experience will be used for the specification of a
new monitor with optimised design, to be operated both in
the SPS and in the LHC.
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| PM16 | The Measurement and Optimisation of Lattice Parameters on the ISIS Synchrotron | diagnostics, ISIS, lattice, synchrotron | 204 | ||
|
The ISIS Synchrotron accelerates a high intensity proton beam from 70 to
800 MeV at 50 Hz. Recent hardware upgrades to the diagnostics,
instrumentation and computing have allowed turn by turn transverse
position measurements to be made. A special low intensity beam can also
be injected for detailed diagnostic measurements. The analysis of such
data at many points around the ring has allowed the extraction of lattice
parameters. This information will have significant application for
improved beam control. The methods of analysis as well as some
applications for setting up and optimising the machine are described in
this paper. Future plans and relevance for high intensity performance is
also given.
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| PM17 | First Beam Tests for the Prototype LHC Orbit and Trajectory System in the CERN-SPS | diagnostics, pick-up, closed-orbit, LHC, collider, controls | 207 | ||
|
The first beam tests for the prototype LHC orbit and
trajectory system were performed during the year 2000 in
the CERN-SPS. The system is composed of a wide-band
time normaliser, which converts the analogue pick-up
signals into a 10 bit position at 40MHz, and a digital
acquisition board, which is used to process and store the
relevant data. This paper describes the hardware involved
and presents the results of the first tests with beam.
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| PM18 | Beam Diagnostics for Low-Intensity Radioactive Beams | diagnostics, isotope-production, EXCYT, emittance | 210 | ||
|
In order to perform imaging, profiling and identification of low
intensity (Ibeam<105 pps) Radioactive Ion Beams (RIB), we have
developed a series of diagnostics devices, operating in a range of beam
energy from 50 keV up to 8 MeV/A. These characteristics do them
especially suitable for ISOL RIB facilities.
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| PM19 | The Dynamic Tracking Acquisition System for DAΦNE e+/e--Collider | diagnostics, pick-up, closed-orbit, controls, collider, DAPHNE | 213 | ||
|
The goal of this paper is to describe the dynamic tracking acquisition
system implemented for the DAΦNE e+/e--collider at LNF/INFN. We have
been using the system since last year and it has been possible to collect
useful information to tune-up the machine.
A four-button BPM is used to obtain the sum and difference signals in
both the transverse planes. The signals are acquired and recorded by a
LeCroy LC574A oscilloscope with the capability to sample the input
waveforms using a beam synchronous external clock generated by the DaFne
Timing System. The start of acquisition is synchronised to a horizontal
kick given by an injection kicker. After capturing up to 5000 consecutive
turns, data are sent through a GPIB interface to a PC, for processing,
presentation and storage. A calibration routine permits to convert
voltage data to millimeters values. The acquisition and control program
first shows the decay time in number of turns. Then it draws a trajectory
in the phase space (position and speed) in both the transverse planes. To
do this the software builds a data vector relative to a second "virtual"
monitor advanced by 90 degrees. This is done by two alternative ways:
applying the Hilbert transform or using the transport matrix method.
Examples of data acquired during the collider tune-up are shown.
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| PM20 | A High Dynamic Range Bunch Purity Tool | diagnostics, ESRF, synchrotron-radiation, emittance | 216 | ||
|
The European synchrotron radiation facility uses a
stored electron beam in order to produce x-rays for the
study of matter. Some experiments make use of the time
structure of the x-ray beam which is a direct reflection of
the time structure in the electron beam itself. Avalanche
photo-diodes have been used in an x-ray beam in a photon
counting arrangement to measure the purity of single or
few bunch filling modes. Conventional techniques
measuring the photon arrival times with a time to
analogue converter (TAC) achieve dynamic ranges in the
10-6 range. We report here the use of a gated high count
rate device achieving a measurement capability of 10-10.
Such high purity filling modes are required in synchrotron
light sources producing x-ray pulses for experiments
looking at very weak decay signals as seen in M”ssbauer
experiments..
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| PM21 | DSP and FPGA Based Bunch Current Signal Processing | diagnostics, ESRF, closed-orbit, controls, simulation | 219 | ||
|
The current in electron storage rings used as synchrotron light sources
must be measured to a very high precision in order to determine the
stored beam lifetime. This is especially so in high-energy machines in
which the lifetime may be very high. Parametric current transformers
(PCT) have traditionally been used to measure the DC or average current
in the machine, which offer a very high resolution. Unfortunately these
do not allow the different components of a complex filling pattern to be
measured separately. A hybrid filling mode delivered at the ESRF consists
of one third of the ring filled with bunches with a single highly
populated bunch in the middle of the two-thirds gap. The lifetime of
these two components may be very different. Similarly the two components
are injected separately and can be monitored separately using a fast
current transformer (FCT) or an integrating current transformer (ICT).
The signals from these devices can be analysed using high speed analogue
to digital converters operating at up to 100MHz and digital signal
processing (DSP) techniques involving the use of field programmable gate
arrays (FPGAs) in order to process the continuous data stream from the
converters.
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| DS03 | Industrial Products for Beam Instrumentation
Session 3: Monday Afternoon (16:30--18:00 Hrs) |
227 | |||
|
In various branches of high technology industry there has been considerable progress
in the past years which could be used for beam instrumentation.
The subject will be introduced by two short demonstrations:
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