| Paper | Title | Other Keywords | Page | ||
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| CT01 | BPM Read-Out Electronics Based on the Broadband AM/PM Normalization Schema | instrumentation, diagnostics, pick-up | 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, pick-up, PSI | 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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| PM03 | Accuracy Of The LEP Spectrometer Beam Orbit Monitors | instrumentation, diagnostics, pick-up, 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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| PM05 | Functionality Enhancement of the Multiplexing BPM System in the Storage of SRRC | instrumentation, diagnostics, SRRC, pick-up, 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, pick-up | 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, APS, pick-up | 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, APS, pick-up | 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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| PM10 | A Logarithmic Processor for Beam Position Measurements Applied to a Transfer Line at CERN | instrumentation, diagnostics, pick-up, 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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| PM17 | First Beam Tests for the Prototype LHC Orbit and Trajectory System in the CERN-SPS | instrumentation, diagnostics, pick-up, 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, pick-up, 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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| PM21 | DSP and FPGA Based Bunch Current Signal Processing | instrumentation, diagnostics, ESRF, controls, simulation | 219 | ||
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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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| DS01 | Orbit Feedbacks for Synchrotron Light Sources
Session 1: Monday Afternoon (16:30--18:00 Hrs) |
feedback | 225 | ||
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The session is meant to serve as a survey giving an overview on the current status of
closed orbit stabilisation and on future needs. Therefore we would be interested to
have from each laboratory/project, where appropriate, transparencies on the following
discussion topics.
The first general part are noise sources for the beam.
The second part concentrates on closed orbit feedbacks including its components.
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