| Paper |
Title |
Page |
| PT01 |
Closed-orbit correction using the new beam position monitor electronic of Elsa Bonn
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153 |
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- J. Dietrich, I. Mohos, J. Keil
IKP, Forschungszentrum Jülich GmbH, Jülich, Germany
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RF and digital electronics, developed at the
Forschungszentrum Jülich/IKP were integrated to form
the new beam position monitor (BPM) system at the
Electron Stretcher Accelerator (ELSA) of the University
of Bonn. With this system the preservation of the
polarization level during acceleration was currently
improved by a good correction of the closed-orbit. All
BPM offsets relative to the magnetic quadrupole centers
were determined by the method of beam-based alignment.
The optics functions measured by the BPM system are in
good agreement with theoretical predictions.
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| PT02 |
Real-time betatron tune measurement in the accelerator ramp at COSY-Jülich
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156 |
| |
- J. Dietrich, I. Mohos
IKP, Forschungszentrum Jülich GmbH, Jülich, Germany
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A new real-time method for betatron tune measurements
at COSY was developed and tested from the
early 1997. A bandlimited broadband noise source was
used for beam excitation, the transversal beam position
oscillation was bunch-synchronous sampled and digitized
with a high resolution ADC. The Fourier transform of the
acquired data represents immediately the betatron tune.
After the first promising experiments an automatic
tunemeter was constructed. The tunemeter is used as
routine diagnostic tool since end of 1998.
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| PT03 |
Measuring beam intensity and lifetime in BESSY II
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159 |
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- R. Bakker, R. Georgen, P. Kuske, J. Kuszynski
BESSY, Berliner Speicherring-Gesellschaft für Synchrotronstrahlung mbH, Berlin, Germany
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The measurement of the intensity of the beam in the
transfer lines and the storage ring are based on current
transformers. The pulsed current in the transfer lines is
measured with passive Integrating Beam Current
Transformers (ICT). The bunch charge is transferred to a
DC-voltage and sampled with a multifunction I/O-board
of a PC. The beam current of the storage ring is measured
with a high precision Parametric Current Transformer
(PCT) and sampled by a high quality digital volt meter
(DVM). A stand alone PC is used for synchronisation,
real-time data acquisition and signal processing.
Current and lifetime data are updated every second and
send via CAN- bus to the BESSY II control system. All
PC programs are written in LabVIEW.
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| PT04 |
Radiation protection system installation for the accelerator production of tritium/low energy demonstration accelerator project (APT/LEDA)
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162 |
| |
- J.E. Wilmarth, M.T. Smith, T.L. Tomei
LANL, Los Alamos National Laboratory, Los Alamos, NM, USA
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The APT/LEDA personnel radiation protection system
installation was accomplished using a flexible, modular
proven system which satisfied regulatory orders, project
design criteria, operational modes, and facility
requirements. The goal of providing exclusion and safe
access of personnel to areas where prompt radiation in the
LEDA facility is produced was achieved with the
installation of a DOE-approved Personnel Access Control
System (PACS). To satisfy the facility configuration
design, the PACS, a major component of the overall
radiation safety system, conveniently provided five
independent areas of personnel access control. Because of
its flexibility and adaptability the Los-Alamos Neutron-
Science-Center-(LANSCE)-designed Radiation Security
System (RSS) was efficiently configured to provide the
desired operational modes and satisfy the APT/LEDA
project design criteria. The Backbone Beam Enable
(BBE) system based on the LANSCE RSS provided the
accelerator beam control functions with redundant,
hardwired, tamper-resistant hardware. The installation
was accomplished using modular components.
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| PT05 |
First results on closed-loop tune control in the CERN-SPS
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165 |
| |
- L. Jensen, O.R. Jones, H. Schmickler
CERN, Geneva, Switzerland
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This paper presents the first measurements performed
with the SPS Qloop. The emphasis will be laid on the
model used for designing the regulation loop and how
well it fits reality.
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| PT06 |
New digital BPM system for the Swiss light source
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168 |
| |
- M. Dehler, A. Jaggi, P. Pollet, T. Schilcher, V. Schlott, R. Uršič, R. deMonte
PSI, Paul Scherrer Institut, Villigen, Switzerland
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This paper presents a new digital beam position monitor
(DBPM) system which is currently under development
for the Swiss Light Source (SLS). It is designed to
provide sub-micron position data in normal closed orbit,
and feedback mode as well as turn by turn information
for machine studies and real time tune measurements.
The self calibrating four channel system consists of a RF
front end, a digital receiver and a DSP module. The same
electronics will be used in all sections of the SLS accelerator
complex. The system can be reconfigured in real
time to perform different kind of measurements like:
pulsed for linac and transfer lines, first turn, turn-by-turn,
closed orbit, feedback and even tune mode for booster
and storage ring. These reconfigurations only involve
downloading of new signal processing software and will
be performed via EPICS control system. An independent
system for monitoring mechanical drifts of the BPM stations
will be installed as well. The measured data will be
permanently updated in a database and taken into account,
when processing the final electron beam positions.
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| PT07 |
Emittance measurements at the new UNILAC-pre-stripper using a pepper-pot with a PC-controlled CCD-camera
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171 |
| |
- M. Dolinska, M. Domke, P. Forck, T. Hoffmann, D. Liakin, A. Peters, P. Strehl
GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
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The complex mathematical algorithms and procedures
to extract emittance data from intensity distributions
measured with a single shot pepper-pot device are
described. First results of mathematical evaluation from
the commissioning of the new GSI pre-stripper linac
structures are presented.
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| PT08 |
A fast protection system for narrow-gap insertion device vessels
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174 |
| |
- M.J. Dufau, R.J. Smith
CLRC, Daresbury Laboratory, Warrington, UK
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Presented in this paper are details of an electronic,
beam position based interlock system, which has been
designed to protect narrow - gap insertion device vessels
from the thermal damage that would result from mis
steered beam. Details of system design and operational
experience are presented, and the paper concludes with an
outline proposal for a system enhancement, that would
offer diagnostic information immediately prior to an
excessive beam displacement trip.
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| PT09 |
The closed-orbit measurement system for the CERN antiproton decelerator
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177 |
| |
- M. LeGras, L. Søby, D.J. Williams
CERN, Geneva, Switzerland
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The closed-orbit measurement system for the new
Antiproton Decelerator (AD) employs 59 electrostatic
pick-ups (PU). The intensity range from 2·1010 down to
107 particles poses challenging demands on the dynamic
range and noise of the head amplifier. A low noiseamplifier
has been developed, having an equivalent input
noise of 0.6nV/√(Hz), allowing beam positions to be
measured to ±0.5 mm with 5·106 particles. Two
different gains take care of the large dynamic range.
After amplification and multiplexing, the PU signals are
fed to a network analyser, where each measurement
point corresponds to one PU. The network analyser is
phase locked to the RF of the AD, thus acting as a
“tracking filter” instrument. An orbit measurement takes
from 0.2 to 12 s depending on the IF-bandwidth of the
network analyser, selected according to the beam
intensity, and the precision required. At the end of the
network analyser sweep the data are read via a GPIB
interface and treated by a real-time task running in a
VME based Power PC.
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| PT10 |
Emittance and dispersion measurements at TTF
|
180 |
| |
- M. Castellano, A. Cianchi, V.A. Verzilov
INFN-LNF, Laboratori Nazionali di Frascati dell'INFN, Frascati, Italy
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It is well known that beam dispersion , along with the
Twiss parameters and emittance, contributes to the beam
spot size. So that, in general, anomalous dispersion is an
undesirable event and must be minimized by careful tuning
the machine. If not, when the spot size is used to infer
beam emittances, as it is the case of the "quadrupole
scan" method, basically employed at TTF, the unknown
dispersion can lead to overestimated values for the emittance.
This paper presents the first attempt to determine the
dispersion function at several points of the TTF Linac and
to separate its contribution to the local emittance measurement,
performed by means of the OTR imaging technique.
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| PT11 |
Dipole modes study by means of HOM couplers at SBTF
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183 |
| |
- N. Baboi, M. Dohlus, A. Jöstingmeier, N. Holtkamp, M. Wendt, M. Nagl, J. Boster, H. Hartwig
DESY, Deutsches Elektronen Synchrotron, Hamburg, Germany
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High order modes (HOM) are generated by the interaction
of a bunched beam with an accelerator environment. They
may act destructively on following particle bunches, leading
to an increase of the transverse oscillation amplitude
and finally to the deterioration of the emittance. Dipole
modes have been studied at the S-Band Test Facility at
DESY. One accelerating structure, specially designed for
this test linac, is equipped with waveguide pick-ups for
measuring the HOMs. For one part of the experiments, a
modulation of the transverse offset of the bunches at the
structure entrance has been induced using a fast broadband
kicker and the effect was measured with a precise stripline
BPM. No high impedance modes were clearly found in the
structure, which has been detuned and damped by both the
tapered geometry of the structure and an absorbing stainless
steel coating applied on the iris tips.
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| PT12 |
Aspects of bunch shape measurements for low, intense ions beams
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186 |
| |
- P. Forck, F. Heymach, U. Meyer, P. Moritz, P. Strehl
GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
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For the characterisation of the ion beam delivered by
the new High Current LINAC at GSI, the time structure
of bunches and the knowledge concerning their intensity
distribution in longitudinal phase space is of great
importance. At least 100ps time resolution and the
capability of measuring long tails in the distribution were
design parameters. Taking advantage of Rutherford-scattering
to reduce the count rate, a direct time of flight
measurement technique using diamond detectors can be
applied. First results are reported. Plans for determine the
energy of individual ions by detecting secondary
electrons emitted from a thin C foil using 1m drift are
discussed.
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| PT14 |
Experience with stripline beam position monitors on the TESLA test facility LINAC
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190 |
| |
- P. Castro, P. Patteri, F. Tazzioli
DESY, Deutsches Elektronen Synchrotron, Hamburg, Germany
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Measurement and correction of beam position are very
important for the optimization of beam characteristics and
alignment in the Tesla Test Facility (TTF) linac. We
describe and present measurements with beam of the
performance of the stripline beam position monitors
(BPMs) in operation and in order to determine the beam
response.
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| PT15 |
High current precision long pulse electron beam position monitor
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193 |
| |
- S.D. Nelson, Y.J. Chen, T. Fessenden, C. Holmes
LLNL, Lawrence Livermore National Laboratory, Livermore, CA, USA
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Precision high current long pulse electron beam position
monitoring has typically experienced problems with high
Q sensors, sensors damped to the point of lack of precision,
or sensors that interact substantially with any beam
halo thus obscuring the desired signal. As part of the
effort to develop a multi-axis electron beam transport system
using transverse electromagnetic stripline kicker technology,
it is necessary to precisely determine the
position and extent of long high energy beams for accurate
beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs
beam pulse, sub millimeter beam position accuracy.)
The kicker positioning system utilizes shot-to-shot adjustments
for reduction of relatively slow (< 20 MHz) motion
of the beam centroid. The electron beams passing through
the diagnostic systems have the potential for large halo
effects that tend to corrupt position measurements.
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| PT16 |
Status of the delta synchrotron light-monitoring-system
|
196 |
| |
- U. Berges, K. Wille
DELTA, Institute for Accelerator Physics and Synchrotron Radiation, University of Dortmund, Germany
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A synchrotron radiation source like DELTA needs an optical
monitoring system to measure the beam size at different
points of the ring with high resolution and accuracy.
The measurements with the present synchrotron light
monitors show that beam sizes larger than 250 μm can be
measured. The measured emittance is of the order of the
theoretical values of the optics and goes down to 8 nm rad.
The magnification of the system can simply be increased
by adding another lens to measure smaller emittances and
beamsizes down to 100 μm. In this case you still have
an optical image of the beam available, but sometimes the
position of the camera has to be adapted due to the great
magnification of the optical system. The image processing
system which is based on a VME Framegrabber makes a
two dimensional gaussian fit to the images from different
synchrotron light-monitors.
First tests with monochromatic components of the synchrotron
radiation (500 nm and 550 nm) and with short
time cameras (shutter time down to 1/10000 s) have been
performed. A two-dimensional PSD has been installed to
measure slow beam motion. To measure small beam sizes,
especially in the vertical plane, diffraction elements will be
used.
This paper gives an overview over the present installation
and the results.
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| PT17 |
Role of pre-wave zone effects in TR-based beam diagnostics
|
199 |
| |
- V.A. Verzilov
INFN-LNF, Laboratori Nazionali di Frascati dell'INFN, Frascati, Italy
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Transition radiation (TR) is nowadays intensively exploited
by a number of techniques to characterize different beam
parameters. These methods are based, sometimes implicitly,
on standard formulae, and used often without paying
due attention to their applicability. In particular, standard
expressions are only first-order asymptotic, i.e., strictly
speaking, valid at infinity. In this paper TR is examined in a
spatial domain where conventional results are no more exact
and variations in radiation properties are observed. Under
certain conditions, for example, at long wavelengths or
very high energies the effect is so considerable that should
be taken into account in accurate beam measurements.
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| PT19 |
A method for measurement of transverse impedance distribution along storage ring
|
202 |
| |
- V. Kiselev, V. Smaluk
BINP, Budker Institute of Nuclear Physics, Novosibirsk, Russia
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A new method for measurement of transverse couple
impedance distribution along storage ring is described.
The method is based on measuring of a closed orbit
deviation caused by local impedance. Transverse
impedance acts on the beam as a defocusing quadrupole,
strength of which depends on the beam current. If a local
bump of closed orbit has been created at the impedance
location, then the orbit deviation occurs while varying
the beam current. The local impedance can be evaluated
using the orbit deviation measured. Measurement
technique is described, the method accuracy is
evaluated. The method described was successfully used
for measurement of the impedance distribution along the
VEPP-4M storage ring.
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