| Paper | Title | Other Keywords | Page | ||
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| IT08 | Breaking New Ground with High Resolution Turn-By-Turn BPMs at the ESRF | instrumentation, diagnostics, ESRF | 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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| CT01 | BPM Read-Out Electronics Based on the Broadband AM/PM Normalization Schema | instrumentation, diagnostics, 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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| CT03 | Performance of the Digital BPM System for the Swiss Light Source | instrumentation, diagnostics, 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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| PS04 | Design of a Magnetic Quadrupole Pick-Up for the CERN PS | instrumentation, diagnostics, 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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| PS07 | New Schottky-Pickup for COSY-Jülich | instrumentation, diagnostics, COSY | 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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| PS14 | Microwave Pickups for the Observation of Multi GHz Signals Induced by the ESRF Storage Ring Electron Bunches | instrumentation, diagnostics, ESRF, storage-ring, emittance | 136 | ||
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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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| PM01 | Position Monitoring of Accelerator Components as Magnets and Beam Position Monitors | instrumentation, diagnostics, DELTA, alignment | 159 | ||
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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 | instrumentation, diagnostics, linac, controls, SPring-8 | 162 | ||
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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 | instrumentation, diagnostics, closed-orbit, LEP, energy-calibration | 165 | ||
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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" | instrumentation, diagnostics, ELBE, linac | 168 | ||
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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 | instrumentation, diagnostics, SRRC, closed-orbit, synchrotron | 171 | ||
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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 | instrumentation, diagnostics, ELETTRA, synchrotron, closed-orbit | 174 | ||
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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 |
instrumentation, diagnostics, controls, closed-orbit, APS | 177 | ||
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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 | instrumentation, diagnostics, controls, closed-orbit, APS | 180 | ||
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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 |
instrumentation, diagnostics, NLC, linear-collider | 183 | ||
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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 | instrumentation, diagnostics, closed-orbit, beam-transport, controls | 186 | ||
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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 | instrumentation, diagnostics, emittance, injection, CERN-PS | 189 | ||
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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 | instrumentation, diagnostics, CERN-SPS, controls | 192 | ||
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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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| PM17 | First Beam Tests for the Prototype LHC Orbit and Trajectory System in the CERN-SPS | instrumentation, diagnostics, closed-orbit, LHC, collider, controls | 207 | ||
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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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| PM19 | The Dynamic Tracking Acquisition System for DAΦNE e+/e--Collider | instrumentation, diagnostics, closed-orbit, controls, collider, DAPHNE | 213 | ||
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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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