Sunday,
October 12, 1997
Sunday,
October 12, 1997
Monday,
October 13, 1997
Tuesday,
October 14, 1997
SUI1 Gravitational Wave Detectors
E. Coccia - Univ. Roma Tor Vergata
SUI2 Diagnostic Use of Digital Beam Feedback Systems
D. Teytelman - SLAC
SUI3 Beam Delivery Systems and Dose Verification Techniques at Heavy Ion Therapy Facilities
D. Schardt - GSI, Darmstadt, Germany
SUI4 Design of Low Coupling Impedance Diagnostics for e+e- Factories
M. Zobov - INFN-LNF
MOI1 Overview of Accelerator Diagnostics
A. Hofmann - CERN
MOI2 Time and Frequency Domain Measurements
K.H. Mess - DESY Hamburg
MOI3 Comparison of Different Methods for Emittance Measurement and Recent Results from LEP
C. Bovet - CERN
TUI1 Diagnostic and
Control of the Time Evolution of Beam Parameters
H. Schmickler - CERN
TUI2 Diagnostics for Ultra
Short Bunches
G. Krafft - TJNAF-CEBAF
TUI3 Low Intensity Ion Beam Diagnostics with Particle Detectors
P. Finocchiaro - INFN-LNS
TUI4 Optical Transition Radiation Diagnostic for Electron Particle Beams
D. Giove - INFN-LASA
SUO1 Integration of Data from the SRS Electron BPMs into the Control System: Present Status and Future Plans
B.G. Martlew, M.T. Heron, M.J. Pugh, W.R. Rawlinson - CLRC Daresbury Laboratory, Warrington, UK
The data from the electron BPMs on the SRS at Daresbury must be interfaced
into a general purpose control system in order to provide beam position
information for use by orbit servo software and for general monitoring
and diagnostic displays. This paper describes how this is currently achieved
and goes on to discuss how the system will be expanded to take account
of the needs of two new multipole wigglers. Possible ways of improving
the performance of the existing system will also be discussed.
SUO2 Latest Results with the ELETTRA Fast Digital Local Feedback
C. J. Bocchetta, D. Bulfone, A. Galimberti, M. Lonza, C. Scafuri, L. Tosi, R. Visintini - Sincrotrone Trieste, Italy
A number of fast digital local orbit feedback systems are being installed
at ELETTRA to improve the stability of the electron beam at the photon
source points. After a short overview of the system design issues, the
latest operational results are presented in terms of the long term behaviour
and the interaction between multiple active feedbacks.
SUO3 LHC BPM Design
J.P. Papis, L. Vos, H. Schmickler - CERN
Already in 1997, 8 years before the expected year of commissioning of
the LHC, the design of the detectors for the LHC orbit system has to be
completely termined. The paper describes the BPM design highlighting the
chain of arguments have led to this particular solution.
SUO4 The Integration of Diagnostics in the DAFNE Control System
C. Milardi, G. Di Pirro, G. Mazzitelli, A. Stecchi - INFN-LNF
Since the Control System of the DAFNE complex proved to be reliable,
from its architecture point of view, and flexible, in driving the machine
low level devices, the efforts were oriented in operating an organic integration
of the existing diagnostics. The very early stage of the DAFNE commissioning
involved elements such as beam position monitors, fluorescent screens,
current toroids, and synchrotron light monitors. A full remote control
for these diagnostics was provided, as well as for a variety of instrumentation:
oscilloscope, voltmeter and multiplexer sets both for analogic and video
signals. The user interfaces for this equipment were developed too, with
full integration in the Control System Graphic User Interface.
SUO5 The Different Uses of an Analog Signal Acquisition System for Beam Instrumentation in the SPS Complex
F. Ferioli, J.J. Gras - CERN
A single data acquisition system able to sample and store every 100
ns analog signals coming from different monitors (i.e. SEM or PhotoMultipliers)
has been used in the SPS complex by three different instruments: the "fast
spill ", allowing the user to observe the intensity evolution of the
extracted beams, the "fast position", giving the beam position
evolution of the injected beams and the "colmon" tracking the
beam losses in the SPS ring. This paper presents briefly the hardware and
the software shared by these instruments and then describes in more detail
these applications and their results.
MOO1 A Comparative Study of Fast Wire-Scanners,
Beamscope and Sem-Grids for Emittance Measurements in the PS Booster
M. Arruat, C. Carli, A. Jansson, M. Lindroos, M. Martini, J. Olsfors, U. Raich, H. Schonauer - CERN
The tight emittance budget , imposed on the production of the high-brilliance
beams in the LHC preinjectors, demands the elimination of all possible
sources of beam blow-up. A prerequisite for this is reliable instrumentation
and evaluation methods for comparison of their data. We have made a study
of three methods for emittance measurement in the PS Booster: fast wire-scanners,
BeamScope, and SEM-grids in a measurement line. For the fast wire-scanners,
a full Monte-Carlo simulation was made of the beam-wire interaction, for
an energy range from 100 MeV to 1 GeV, and compared to measured values.
Data from a scraping method (BeamScope) are compared to profile measurements,
using Abel-type integral transformations. Results will be presented.
MOO2 Beam Nonuniformities and Halo
N. Pichoff (1) and G. Haouat (2) - (1) CEA-Saclay, DSM/LNS-GECA, Gif-sur-Yvette, France - (2) CEA-Bruyeres, DAM/DRIF/DPTA/SP2A, Bruyeres-le-Chatel, France.
Halo formation induced by transverse-density nonuniformities in an intense
electron beam has been experimentally investigated. An experiment has been
performed with a 2 MeV electron beam from the photo-injector of the ELSA
linac. The initial beam profile is defined by masks of different shapes
in front of the photo-cathode, downstream of the drive-laser. The beam
transverse distribution is measured at three diagnostic stations located
along the transport channel. This experiment is unique in its ability to
perform profile measurements over a wide dynamic range. Data were obtained
for beam peak currents ranging from 10 to 100 A and for various transport
configurations. Experimental results and their interpretation in terms
of particle redistribution will be presented.
MOO3 First Results from the Enhanced Diagnostic in the Final Focus for the 1997 SLC Run
P. Raimondi, C. Field, D. McCormick, N. Phinney, M. Ross, R. Traller, T. Usher, M. Woodley, M. Woods, F. Zimmermann - SLAC
To improve the performance of the SLC FF, for the 1997 run, significant
upgrades were made to the diagnostic Systems. High resolution beam position
monitors provide an accurate determination of the beam trajectory and greatly
increase the accuracy of the beam size measurements. Additional wire scanners
were also installed in the middle of the Final Focus. New counters to detect
low angle scattered Bhabha particles and beamstrahlung radiation provide
enhanced luminosity diagnostics. An RF bunch length monitor was installed
near the Interaction Point to continuosly monitor the longitudinal beam
size.
MOO4 Commissioning the Beam Diagnostics for the PEP-II B Factory
A.S. Fisher, D. Alzofon, B. Collins, A. Gioumousis, T. Himel, R. Iverson, R. Johnson, A. Kulikov, R. Larsen, D. McCormick, J. Seeman, S. Smith, R. Stege, H.U. Wienands - SLAC; M. Chin, J. Hinkson, M. Zisman - Lawrence Berkeley National Laboratory
PEP-II is a 2.2-km-circumference collider with a 2.1-A, 3.1-GeV positron
ring (the Low-Energy Ring) 1 m above a 1-A, 9-GeV electron ring (the High-Energy
Ring); both rings are designed for a maximum current of 3 A. We describe
the beam diagnostics and present measurements from HER commissioning, expected
to start in April 1997. LER commissioning will begin with the injection
region in September, followed by full ring turns in early 1998. The beam
size and pulse duration are measured using near-UV synchrotron light extracted
by grazing-incidence mirrors that must withstand up to 200 W/cm. Normally
1658 of the 3492 buckets will be filled, and the charge must be equal within
2%. To measure the charge in each bucket with an accuracy of ~0.5%, the
sum signal from a set of 4 pickup buttons is digitized and averaged over
256 samples per bucket in every 60-Hz interval. The sum is then normalized
to the ring current, measured by a DC current transformer. The 300 beam-position
monitors per ring are multiplexed to share 171 processor modules, which
use DSPs for recording positions over 1024 turns and for calibration. For
both diagnostics and machine protection, 100 photomultipliers with fused-silica
Cherenkov radiators measure beam losses and can trigger a beam abort in
case of high loss. For the ring tunes, signals from a set of 4 pickup buttons
arecombined into horizontal, vertical, and sum signals. Two signals are
selected and downconverted into the range of a 10-MHz, 2-channel, programmable,
DSP-based spectrum analyzer, which is connected over ethernet to the control
room.
MOO5 Diagnostic System of INDUS-1
Anil Banerji - Centre for Advanced Technology, Indore, India
The INDUS-1 synchrotron radiation source is a 0.45 GeV electron storage
ring. It consists of a 20 MeV microtron, a booster synchrotron and full
energy injection into INDUS-1. Transfer line-1 and transfer line-2 connect
the microtron to the synchrotron and the synchrotron to INDUS-1, respectively.
The transfer lines have been provided with fluorescent screens, current
transformers and secondary emission wire grid monitors. The booster synchrotron
and INDUS-1 have fluorescent screens, fast current transformers, DC current
transformers, synchrotron light monitors, beam shakers and beam position
monitors.
MOO6 Operational Experience with the DAFNE Beam Diagnostics System
M. Serio, DAFNE Team - INFN-LNF
Overview and description of the diagnostic systems in the DAFNE complex
and their recent use in bringing up the accelerators and transfer lines.
TUO2 OTR Measurements for the TTF Commissioning
M. Castellano, L. Catani, A. Cianchi, D. Digiovenale, M. Ferrario, P. Patteri, S. Tazzari, F. Tazzioli - INFN-LNF
The TESLA Test Facility (TTF) Linac is a 500 MeV Superconducting Linac
in costruction at Desy Laboratory (Hamburg) by an international collaboration
aimed at establishing operative conditions for accelerating structures
with gradients above 15 MeV/m. TTF is the first machine in which Optical
Transition Radiation (OTR) has been considered from the design stage as
one of the main diagnostic tools. In this paper we will present the results
of OTR beam measurements performed in the TTF injector and module 1 commissioning.
In particolar, beam profiles as function of a quadrupole strength have
been used to derive the transverse emittance. Beam energy is obtained on-line
from the OTR angular distribution, giving a powerful instrument to the
operator in setting the RF parameters. The use of a gated intensified camera
allows also to measure the stability of the beam along the macropulse,
both in position and energy.
TUO3 Measurement Results with the BEXE Detector at LEP
C. Bovet, D. Cocq, A. Manarin, E. Rossa, H. Schmickler, G. Voors - CERN
Two detectors based on fast CdTe photoconductors are installed in LEP
for the measurement of the vertical beam profiles and for an observation
of the bunch length via autocorrelation. Due to the fast response time
of these detectors the beams can be observed turn by turn. With a fast
gating (10ns) of the polarization voltage of the detectors even single
bunches of LEP bunch trains can be selected for measurements. The paper
gives typical measurement examples and describes the calibration procedure.
Special emphasis is given on the use of the vertical profile monitors as
real time display in the LEP control room.
TUO4 Bunch Length Measurements at ELETTRA
M. Ferianis, M. Pros, A. Carniel, R. De Monte - Sincrotrone Trieste, Italy
ELETTRA is a third generation synchrotron light source in operation
in Trieste, Italy since 1993. A significant machine parameter to measure
is the bunch length, as it allows a direct derivation of fundamental machine
parameters, like its broadband impedance. This measurement is critical
in third generation synchrotrons due to the very short duration of the
synchotron ligth pulse which lies in the range of pico-seconds. Furthermore,
the measurement is critical due to low energy per pulse. In this paper,
a review of the Bunch Length measurements performed at ELETTRA is reported:
different methods are here described and the measured data presented. Particularly
interesting is the fact that methods using different acquisition techniques,
namely single-shot and sampling, have given consistent results. Some ideas
for future upgrading of the tested systems are also presented.
TUO5 Development of Jitter-Free, Laser Triggered X-Ray Streak Camera with Femto Second Time Resolution
K. Scheidt - ESRF, Grenoble, France
A collaboration project between the ESRF and the Centre for Ultra fast Optical Science (CUOS) aims at the development of an accumulating Streak Camera system with femto second time resolution for X-rays up to 40KeV. A technique innovated by the CUOS employs a GaAs photo-switch that provides a jitter-free High Voltage signal for the Streak Camera's deflection plates, the photo-switch itself is triggered by a small energetic fraction of a 1mJ, 150 femto second laser pulse provided by a commercial Ti:Saph laser and regenerative amplifier at up to 1Khz repetition frequency. The jitter-free triggered Streak Camera has to be seen as the ultra-fast detector in a specific measurement concept in which the same 150fs laser pulse optically stimulates an ultrafast reaction in a sample that is probed by a broad, say, 100ps X-ray pulse coming from a dedicated ESRF beamline. This concept allows to perform time resolved X-ray scattering experiments with sub-pico second time resolution determined by the Streak Camera and the laser as trigger & excitation source and not limited by the 100ps probing X-ray pulse as is the case in more classical measurement concepts. With special photo-cathodes of reasonable DQE for high energetic X-rays and a cooled CCD read-out system this jitter-free accumulating Streak Camera can obtain an excellent dynamic range on ultra fast phenomena of very weak amplitude.
SUP1 Beam Position Measurement inside the FEL-Undulator
at the TESLA Test Facility
R. Lorenz - TU Berlin, Berlin, Germany; T. Kamps - DESY-IfH Zeuthen; M. Wendt - DESY Hamburg
Beam-based alignment is essential for the operation of a SASE-FEL at
the TESLA Test Facility. It requires the transverse position to be measured
at several points inside and between the undulator modules with a resolution
of better than 5 microns. Between the undulator modules cylindrical cavities
will be used. The amplitude of the TM110-mode excited by an off-axis beam
will be detected in a homodyne receiver by mixing the cavity output and
a 12 GHz reference signal down to DC. Inside each module, a large number
of monitors according to the number of steering stations, will be installed.
They have to fit into the undulator gap of 12 mm. Two different monitor
concepts are considered. One is a modified button-type monitor, using small
rf-feedthroughs as antennae. The other one uses a new microwave concept.
It consists of four waveguides coupled by small slots to the magnetic field
of the electron beam. The averaged position of a bunch train will be measured
in a narrowband X-band receiver. Prototypes of all monitors were built
and tested. The paper summarizes the designs, signal processing schemes
and first test results for all monitors.
SUP2 Beam Position Monitor for the DAFNE Interaction Regions
A. Stella, A. Ghigo, F. Sannibale, M. Serio, C. Vaccarezza - INFN-LNF
In DAFNE, in order to achieve the high luminosity required, electrons
and positrons are stored in two separated storage rings laying in the same
horizontal plane, with horizontal crossing in 2x10m long interaction regions
(IR), at an angle of ±12.5 mrad. During the first period of operation
with DAFNE, redundant instrumentation has been placed in the IR's, to allow
fine tuning of the machine parameters, in particular to correlate beam
luminosity and position along the IR's. In these regions the small space
avalaible, together with the variable cross-section of the vacuum chamber,
prevents from the use of directional striplines to measure the position
of the two opposing beams. For this reason a particular configuration of
electrostatic beam position monitors (BPM) with six buttons has been developed.
This paper deals with the characterization of such a diagnostic device,
showing our approach to the problem of giving a measurement of one beam
position reasonably decoupled from the other. Numerical and measurement
data are compared for two configurations of six buttons BPM, actually installed
in the DAFNE main rings.
SUP3 Broadband Beam Position Monitor for TTF
M. Juillard, M. Lalot, Ch. Magne, A. Mosnier, B. Phung - CEA, Saclay, France
A beam position monitor for the Tesla Test Facility has been designed
and tested, following a principle initially proposed by R. Bossard from
CERN. The axial symmetry of the reentrant cavity and a calibration box
ensure a high precision measurement. The broadband operation allows a 5
micrometers resolution for the low charge bunches of the Injector 1 and
a 100 nanometers resolution for the 8 nC, 1 MHz electrons bunches of the
Injector 2. The BPM has undergone warm tests and calibration on bench at
SACLAY. Two monitors have been installed on the TTF Injector 1 at DESY,
one in the capture cavity cryostat, another before the first cryomodule,
an have also been successfully tested.
SUP4 A Fast Global Feedback System to Correct
the Beam Position Deviation in the ESRF Storage Ring
E. Plouviez - ESRF, Grenoble, France; S. Eandi - Politecnico Torino, Italy
ESRF is presently developping a fast global orbit correction system
in order to reduce the orbit vertical distortions due to the mecanical
vibration of the girders supporting the magnets. The main parameters of
this system have been determined according to our experience of other orbit
correction systems already implemented at ESRF: - The slow orbit correction
system already in operation. - A fast local feedback system implemented
on two straight sections. These parameters are: - bandwidth of the correction:
0.01 to 200 Hz - number of BPMs and correctors : 16 The correction is based
on the SVD analysis of the machine response to individual correctors. The
fast corrections will be computed by a floating point DSP connected to
the BPMs and correctors through a digital data link. We presents the implementation
of the system (BPMs RF and digital electronics), simulations and experimental
results and address what we think are the important issues for such a system.
SUP5 A New Automated Electron Beam Position Monitor Calibration Facility for the Synchrotron Radiation Source Upgrade at Daresbury
M.J. Collier, C.L. Dawson, D.M. Dykes, P.A. McIntosh, A.R. MacDonald, A.J.ÊMoss, R.J. Smith - CLRC Daresbury Laboratory, Warrington, U.K.
The future implementation of multipole wiggler (MPW) insertion devices
within the current Synchrotron Radiation Source (SRS) lattice has provided
the opportunity to develop a higher quality Electron Beam Position Monitor
(EBPM) calibration facility. This system will be compatible with the requirements
of a third generation light source such as DIAMOND, the proposed future
SRS replacement. The system is based on a precision stepper motor drive
arrangement, which will be used to sweep a wire through the vessel aperture.
This allows full two dimensional vessel mapping for calibration and to
establish the true electrical centre for vessel survey. The entire system
will be controlled by a LabVIEW Virtual Instrument to give automated operation
of wire position and data acquisition. Previous calibration methods relied
on careful control of pickup capacitance to allow low frequency calibration
to be performed. With this new facility, provision has been made to perform
reliable measurements at higher frequencies, including the actual operating
frequency.
SUP6 Recent Developments in Orbit Feedback on the SRS at Daresbury
B.G. Martlew, S. F.Hill, S.L. Smith - CLRC, Daresbury Laboratory, Warrington, U.K.
Local vertical and global horizontal orbit feedback systems have been
in routine use on the SRS at Daresbury since 1994 and are now an essential
element in providing a stable photon beam to experimental stations. A brief
review of the latest operational performance of these systems is followed
by details of enhancements under development including automatic global
orbit feedback during an energy ramp and techniques for improving the performance
of the local feedback systems.
SUP7 Trajectory Measurement of Bunches Ejected from the Cern PS Booster
M. LeGras and D.J. Williams - CERN
The PSB transfer line recombines beams from the 4 vertically stacked
rings of the Booster and sends them to 1 of 3 possible destinations: the
26 GeV PS, the ISOLDE facility, or a measurement line. To acquire the transverse
positions of the beam, there are 18 electrostatic pick-ups. Variable-gain
triple-channel amplifiers (Delta H, Delta V and Sum), with a calibration
system that operates on every cycle, are mounted on each pick-up. Digitisation
is achieved with 8-bit 250 MHz ADC VME modules. Data treatment allows simultaneous
calculation of the beam position, corresponding to each of the 4 rings,
for all pick-ups on every cycle, as well as calibration, base-line correction
and auto-ranging for optimising the resolution of the fast ADCs. Resolution
is 0.3 mm (FS=33 mm) over an intensity range of 100, for a maximum of 1E13
protons per ring. Data treatment is performed as a real-time task in a
VME crate equipped with a Motorola MVME147 CPU board and conforms with
the standard instrumentation protocol as well as the PS control system.
The PSB transfer line recombines beams from the 4 vertically stacked rings
of the Booster and sends them to 1 of 3 possible destinations: the 26 GeV
PS, the ISOLDE facility, or a measurement line. To acquire the transverse
positions of the beam, there are 18 electrostatic pick-ups. Variable-gain
triple-channel amplifiers (Delta H, Delta V and Sum), with a calibration
system that operates on every cycle, are mounted on each pick-up. Digitisation
is achieved with 8-bit 250 MHz ADC VME modules. Data treatment allows simultaneous
calculation of the beam position, corresponding to each of the 4 rings,
for all pick-ups on every cycle, as well as calibration, base-line correction
and auto-ranging for optimising the resolution of the fast ADCs. Resolution
is 0.3 mm (FS=33 mm) over an intensity range of 100, for a maximum of 1E13
protons per ring. Data treatment is performed as a real-time task in a
VME crate equipped with a Motorola MVME147 CPU board and conforms with
the standard instrumentation protocol as well as the PS control system.
SUP8 A DSP Controlled Position Measurement Equipment for Pulsed Beams in Tranfer Lines
M. Bengtsson, T. Bergmark, D. Reistad - The Svedberg Laboratory, Uppsala, Sweden
An equipment has been constructed and used for nondestructive measurements
of beam position in transfer lines from the Gustav Werner cyclotron. A
digital signal processor (DSP) is used to control measurement functions
such as triggering, gain/attenuation adjustments, channel normalization,
drift compensation, and position evaluation. Beam pulses or external signals
can trigger measurements. Interference from the cyclotron RF system is
reduced by operation at the 4th harmonic of the frequency of this RF system.
The DSP communicates to a higher level in the accelerator control system
where it will be possible to control and stabilize the beam position.
SUP9 Performance of the SSRL Beam Position Monitor Processing System
J. Sebek, R. Hettel, D. Martin, D. Mostowfi, R. Ortiz, J. Wachter - SSRL/SLAC
The Stanford Synchrotron Radiation Laboratory has developed a new beam
position monitor (BPM) processing system having first-turn, turn-by-turn,
and high resolution averaged orbit sampling capabilities. The 717 MHz beam
signals (second harmonic of the SPEAR ring RF) sensed by each of the four
BPM buttons are multiplexed into an RF-IF converter. The 6.4 MHz IF signals
(5 times the ring revolution frequency) from each BPM are further multiplexed
into an ADC (sampling at 32 times the revolution frequency) and digital
receiver that produces an I and Q amplitude for the detected signal once
every revolution period. This information can then be averaged over many
revolutions, or used for turn-by-turn orbit monitoring. When averaging
over a synchrotron oscillation period, a 4-channel digital processing system
can produce a complete orbit having a few microns resolution from the 37
active SPEAR BPMs on the order of a millisecond, suitable for use by a
fast global orbit feedback system. Design issues and performance of the
processing system will be presented.
SUP10 Operation and Control of the Slow Beam Motion Monitor at ELETTRA
M. Ferianis, M. Bossi, A. Carniel, R. De Monte, G. Mian - Sincrotrone Trieste, Italy
An electro-optical system has been developed at ELETTRA to monitor the
beam motion in the transverse plane. The system, which has been put into
operation, uses a two-dimensional linear position sensing photodiode on
which the synchrotron radiation used for the profile monitor is focused.
An analogue electronic front-end box computes the difference signals, of
both X and Y planes. A dedicated VME board digitizes these signals and
generates on a Local Process Computer (LPC) a time array of the digitized
data which is made available to the Control System workstations. The Photodiode
is mounted on a motorised two-axes translation stage driven by a real-time
process running on the LPC. This allows the automatic alignment of the
centre of the photodiode (10x10 mm wide) on the beam, so that small mis-alignments
from run to run are easily compensated. A resolution on the micrometer
level is obtained with this set-up in the full 10 mm range. The bandwidth
of the analogue front-end box exceeds 2.5 KHz.
SUP11 Extracted Beam Intensity and Position Measurements at the IHEP
A. G. Afonin, V. N. Gres, V. I. Terekhov - IHEP, Protvino, Russia
In the course of upgrading the Extraction System at the IHEP we are
developing new diagnostic tools to measure the beam intensity in the range
10E8 - 3*10E13 ppp for slow and nonresonant slow extraction as well as
the extraction efficiency and beam position on the bunch by bunch basis
for the fast extraction. A five-electrode second emission chamber as a
monitor followed by a Current-to- Frequency Converter with a conversion
ratio of 1 Hz/pA, is used to handle the problem of slow ejected intensity.
The precision measurement of ejected efficiency is solved by using a single
Beam Current Transformer, mounted in front of the exit window of the accelerator
so, that it envelops both the circulating and ejected beams. Readings of
the intensities of the bunches taken sequentially before and during extraction
allow one to calculate efficiencies for each bunch and overall. To monitor
the beam position signals from two opposite electrodes of PUs are time
multiplexed and procecced by a common electronics. This paper describes
the main components of the diagnostic tools, gives errors analysis and
calibration procedure.
SUP12 Status of the DELTA Beam Based BPM Calibration System
A. Jankowiak, K. Wille - Institute for Accelerator Physics / University of Dortmund, Germany
For a synchrotron radiation source it is necessary to operate a measuring
system which allows to determine the beam position with high resolution
and great accuracy with respect to the axis of the quadrupole magnets.
The results of the calibration measurements with the present bpm system
show that the design resolution (10um) of the system is reached but the
bpm offsets with respect to the magnetic center of the quadrupols is not
precise ascertainable. For some bpms it is in the order of several 100um.
Therfore it was decided to install a beam based bpm calibration system.
At the moment it is planed to install a system which allows to change the
focussing strength of each quadrupole either in a static or dynamic way.
By steering the beam in the quadrupole magnets and minimizing the resulting
orbit distorsion it is possible to determine the magnetic center of each
quadrupole and to get a absolut calibration of each bpm. Furthermore this
system provides the possibilty to measure the local beta-function in each
quadrupol. In this paper the present installation and first results of
test measurements will be presented.
SUP13 Measuring Thousand Turns of the ESRF's Closed Orbit with a Simple Extension to the Existing BPM System
K. Scheidt - ESRF, Grenoble, France
A relatively simple extension to the existing Beam Position Measurement
(BPM) system of the ESRF's Closed Orbit permits the measurements of the
beam position on a large number of individual orbit turns (Thousand Turns
or TT hereafter) on each BPM station. The existing BPM system has 2 modes
of operation : Closed Orbit with minimum integration time of 1ms, and First
Turn with measurement on only one of the first 8 turns after injection.
The ESRF orbit turn time of 2.8uS and the BPM system employing a RF multiplexing
concept would normally deem the system incompatible to perform rapid measurements
of local Beta values and phase advances in the ESRF machine which require
a largely superior bandwidth, acquisition rate and data storage of the
BPM system. However, the technique of a repetitive beam stimulation synchronised
with both the Qtune value and the acquisition of the TT extension, combined
with the use of available large bandwidth RF processor on existing electronics
and the development of a specific high rate digitizer makes it possible
to fulfil the desired functionality at reasonable costs.
SUP14 The DAFNE Broadband Button Monitor
F. Marcellini, M. Serio, A. Stella, M. Zobov - INFN-LNF
The Phi-factory DAFNE is a e+e- double ring collider designed to reach
a luminosity of 5*10^32 cm^-2 s^-1 at the energy of 1020 MeV in the centre
of mass. In order to achieve the required luminosity a very high average
current (up to 5.2 A), distributed over 120 bunches, has to be stored in
each ring. The multibunch operation needs the development of efficient
longitudinal and transverse bunch-by-bunch feedback systems in order to
damp possible beam instabilities. In the feedback systems, the DAFNE Broadband
Button Monitors will be used to detect the individual phase and transverse
offset of each bunch, without memory of preceding ones. Design criteria,
numerical simulations and measurements of transfer and coupling impedances
are described. The obtained results are in a good agreement with the analytical
estimates; in particular they show a flat and broad response in the frequency
range of interest (1.3Ö2.2 GHz), an acceptable transfer impedance
value (~0.5 Ohm) and no resonances within the bunch spectrum.
SUP15 Monitoring Bunch Transfers with Subnanosecond Accuracy Using a Time Vernier Technique
H. T. Duhme and S. Paetzold - DESY Hamburg
Transferring bunch groups of protons and positrons from the interim
ring-accelerator PETRA to the double storage ring HERA by controlling ejection/injection
timing is a complex task, handled by the Transfer Control Equipment. In
order to predict target buckets in HERA before the actual transfer is triggered,
an industrial time interval counter has been used in the past which measured
relative phase of HERA versus PETRA revolution pulses at the moment of
a proposed transfer. This crystal-controlled counter with an accuracy of
about one nanosecond will be replaced by a newly developed revolution watcher
showing an accuracy of better than 100 picoseconds by applying a special
vernier technique to the revolution pulses and the slipping bunch clocks
from the PIT (Petra Integrated Timing) and the HIT (Hera Integrated Timing)
time maker systems. It contains one fast D-Flipflop and some slow counters
in a programmed logic device only. By this mean not only the proton and
positron transfers can be monitored but also the critical synchronisation
process between the proton and positron bunches in the two HERA rings.
SUP16 VME-Based Remote Instrument Control without Ground Loops
J. Belleman, J. Calvin, J.L. Gonzalez - CERN
New electronics has been developed for the remote control of the pick-up
electrodes at the CERN Proton Synchrotron (PS). Communication between VME-based
control computers and remote equipment is via full duplex point-to-point
digital data links. Data are sent and received in serial format over simple
twisted pairs at a rate of 1 Mb/s, for distances of up to 300 m. Coupling
transformers are used to avoid ground loops. The link hardware consists
of a general-purpose VME-module, the 'TRX' (transceiver), containing four
FIFO-buffered communication channels, and a dedicated control card for
each remote station. Remote transceiver electronics is simple enough not
to require micro-controllers or processors. Currently, some sixty pick-up
stations of various types, all over the PS Complex (accelerators and associated
beam transfer lines) are equipped with the new system. Even though the
TRX was designed primarily for communication with pick-up electronics,
it could also be used for other purposes, for example to form a local area
network.
SUP17 EMC/EMI Measurements on Instrumentation VXI Modules (is CE Compliance Enough for Proper Operation in Accelerator Environments?)
M. Ferianis, R. De Monte, F. Pettarin, L. Cristoforetti *, L. Lunelli *, R. Pontalti * - Sincrotrone Trieste, Italy - * CMBM-ITC Trento, Italy
Electro-Magnetic Compatibility (EMC) and Electro-Magnetic Interference
(EMI) considerations play a key role in the design of electronic boards
for accelerator Diagnostics. This is due the severe Electro-Magnetic (EM)
environmental conditions which are normally found in areas where High Precision
electronic equipment has to operate. Furthermore, the CE marking on any
electronic product requires the equipment to be compliant to EMC european
directive. In this paper, the EMC/EMI tests performed on the electronic
boards designed at ELETTRA are presented. The obtained results are compared
both to the regulation masks and to the real EM levels that can be found
in an Accelerator environment. The purpose of such a comparison is to find
out whether the EMC/EMI european regulations, which holds for industrial
electronics, are also sufficiently adequate to assure proper operation
in the Accelerator environment.
SUP18 The PETRA Undulator Control and Interlock at DESY
Matthias Werner - DESY Hamburg
In March 1995, the PETRA Undulator at DESY was commissioned, now producing
a 5 kW photon beam from electrons or positrons of 12 GeV and 40 mA on a
target 130 m away from the source. The system is equipped with a position
control (based on tungsten blade photo monitors, reducing the position
error at the target to the order of 10-20 um) and a fast interlock (mainly
based on a carbon foil, protecting the beamline against damage from the
beam). The report describes the setup and the first operation experience
with the system, operated under routine machine conditions since spring
1996.
SUP19 A Single-Bunch Current Measurement System for Accelerators and Transport Lines at DESY
R. Neumann, M. Wendt - DESY Hamburg
At the Desy accelerator complex inductive pickups deliver suitable signals
for single bunch / single pass current data monitoring. A modular, PC-based
instrumentation system with analog and trigger signal processing sections
is presented.
SUP20 Use of DSP Based Systems for the ESRF Storage Ring Diagnostic & Beam Position Feedback
J.M. Koch - ESRF, Grenoble, France
The diagnostics and the position feedbacks are very demanding in signal processing. Using a DSP based system is a very powerful and flexible solution. Both fix point and floating point systems are used at the ESRF. A first application is a longitudinal beam instabilities detector. The algorithm computes a spectrum analysis of an energy related beam position signal and detects the frequency lines corresponding to the instability. Another application is a tune monitor. It is possible, using a floating point DSP board, to embed an algorithm which is able to reject some spurious lines from the very low level signal coming from the BPMs, and to give fast results. An application is under development that needs many DSPs: a global beam position AC feedback. From BPMs reading to steerers setting, the whole system is uniquely composed of DSP boards, this permits a correction rate of 4kHz with 16 BPMs and 16 steerers. The description of all the materiel and tools involved is given as well as precise details of how their integration within existing constraints has been handled.
MOP1 A Single Shot Emittance Measuring System
for Intense Heavy Ion Beams
M. Domke, Chr. Dorn, P. Forck, H. Kraus, A. Peters, P. Strehl - GSI, Darmstadt, Germany
The intensity upgrading program at GSI will result in considerable changes
in the prestripper region of the Unilac. A single shot emittance measuring
system has been designed to prove the performance of the new prestripper,
which will consist of an RFQ-section followed by an IH-DTL-structure. From
a single macropulse the transverse emittance of both planes will be evaluated
by using a pepperpot in front of a viewing screen and a modern high resolution
CCD-camera including appropriate optics. The video signals are on-line
digitized in the camera system and transmitted via fiber optics to a PC
which will be used for parameter setting signal evaluation and presentation
of results. The new device is also provided to avoid mismatching in the
prestripper, to study space charge effects and to assess new types of ion
sources. The relevant design parameters will be presented for discussion.
First results using a simulation of the ion beam by a light source will
be reported.
MOP2 Emittance Measurement at the Amsterdam Pulse Stretcher
R. Tamoschat (1), N. Marquardt (2), R. Maas (1), G. Luijckx (1) - (1) NIKHEF, (2) DELTA
First results of an experiment dedicated to determine the electron beam
transverse emittance at the Amsterdam Pulse Stretcher ring are presented.
The emittance is derived from measurements of the transverse beam profile
based on laser Compton scattering. The electron beam is scanned under 90
deg by a well focused, high power laser beam. From the change in the energy
rate of the Compton scattered photons due to the scanning the electron
beam profile is deduced. A comparison with data obtained by a profile monitor
using synchrotron radiation is given.
MOP3 Secondary Emission Electron Detectors for Fixed Target Experiments at Fermilab
Gianni Tassotto - Fermilab
Secondary Emission Electron Detectors (SEEDs) have been built and are
being tested for two 800 GeV hi-intensity experiments. These devices have
been designed to display beam profile and beam position to better than
25 micro meter accuracy.
MOP4 NIM-PC Based Read-Out Electronics For Residual-Gas Ionization Beam Profil Monitors at the CRYRING
A. Kallberg and A. Paal - Manne Siegbahn Laboratory at Stockholm University, Stockholm, Sweden; J. Gal, J. Molnar and G. Szekely - Institute of Nuclear Research, Debrecen, Hungary
Residual-gas ionization beam profile monitors have been developed for
the storage ring CRYRING to measure the horizontal and vertical profiles
of the cooled stored ion beams with a spatial resolution of +/-(0.2-0.3)mm.
Since the ion rates are relatively low in all monitors, a chevron assembly
is used with a resistive anode as a detector head. Four charge sensitive
preamplifiers integrate the charges at each corner of the resistive anode.
A fifth pre-amp is used for timing. The preamplifiers and the resistive
biasing network are mounted across the vacuum feedthroughs. After pulse
shaping, amplifying and stretching, the X and Y spatial coordinates of
each detected event are computed from the ratio of charge amplitudes with
the help of analog dividers. The digitized X and Y position data are stored
in a PC by a dedicated dual-port incrementing matrix memory card. Under
software control, data can be accumulated and simultaneously the matrix
can be read out and the display screen updated.
MOP5 Diamond Detectors for Beam Diagnostics in Heavy Ion Accelerators
P. Moritz, E. Berdermann - GSI, Darmstadt, Germany
The application of (CVD-) diamond detectors for beam diagnostics in
heavy ion accelerators will be presented. Recent developments of these
new particle detectors allow beamline particle counting for beam diagnostics
in a non-destructive transmission mode at moderate particle energy losses.
The generated very short detector pulses (<600ps pulse width) give count
rates well beyond 10E8 particles per second. The recommended electronics
and the solution of high frequency problems (e.g. transmission line matching
and frequency response equalization will be described.
MOP6 Optical and time-resolved diagnostics for AIRIX high current electron beam
C. Bonnafond, J. Bardy, A. Devin, E. Merle*, C. Vermare, D. Villate - CEA-CESTA, DEV/SRIA, Le Barp, France - *CEA-VM, Pontfaverger-Moronvilliers, France
AIRIX is a linear induction accelerator that will produce a 17 MeV,
3.5 kA, 60 ns electron beam. It is now in the PIVAIR prototype phase wich
is a validation for AIRIX at 8 MeV. Optical and time-resolved diagnostics
are studied in particular to measure the emittance of the beam. We present
two destructive techniques; the pepper-pot and three gradient method associated
respectively with a fast scintillator and an optical transition radiation
(OTR) or Cerenkov radiation (CR) target. In the first method, we analyse
the beam perturbations caused by the pepper-pot. In the second one, we
discuss about the differences we observe when we measure the beam diameter
with OTR and CR simultaneously, and we present the consequences for the
emittance measurement.
MOP7 Absolute Energy And Longitudinal Emittance Measurement Of Heavy Ion Beam Using Fast Faraday Cups
A. Dainelli, M. Poggi - INFN-LNL
The use of fast Faraday cups (FFC) as a tool to characterize the ion
beam from the point of view of its longitudinal emittance and absolute
energy measurements is here reported. An accuracy of 5x10-4 has been reached
for the beam energy. A review of the three gradients method for longitudinal
emittance measurement is also given.
MOP8 A Non Destructive Way to Measure Betatron Mismatch at Injection
K. Wittenburg - DESY Hamburg
Betatron mismatch in a chain of proton (or ion) accelerators will blow
up the emittance of the beam. Following the ideas of Ref. 1, we study the
use of the Residual Gas Ionization Profile Monitors to measure the mismatch
without disturbing the beam. A turn by turn readout can be performed by
electrical or video readout. The sensitivity of the monitor is adjustable
over a few decades by a local gas bump. First studies at DESY III will
be presented. Ref. 1: C. Bovet, R. Jung; LHC-Project-Report 3 (1996).
MOP9 Beam Diagnostic Instruments for RIKEN Ring Cyclotron
Masayuki Kase, Misaki Kobayashi, Akira Yoneda, Ichiro Yokoyama RIKEN (The Institute of Physical and Chemical Research) - Japan
All kinds of beam diagnostic instruments will be reported, which have
been used for the RIKEN Accelerator Research Facility (the K540 RIKEN Ring
Cyclotron and its two kinds of injectors, heavy ion linac RILAC and K70
AVF cyclotron). They include a wire scanner type profile monitor, a phase
measurement system using MCP, and emittance measurement using two gas counters
(PPAC). Every monitor is required to cover the wide range of beam energy
and beam intensity as well as beam kinds.
MOP10 Detectors for Slowly Extracted Heavy Ions at the GSI Facility
Peter Forck, Tobias Hoffmann, Andreas Peters - GSI, Darmstadt, Germany
At the GSI laboratory, Darmstadt, the whole spectrum of heavy ions can
be accelerated by the synchrotron SIS to energies between 50 MeV/amu and
2 GeV/amu. With a recently developed and successfully used triple of particle
detectors mounted on one feedthrough the whole range of particle currents
between 10^4 pps (particles per second) and 10^11 pps of slowly extracted
ions can be determined: Scintillators for intensities up to 10^6 pps, ionization
chambers for the intermediate range between 10^4 pps and 10^9 pps and secondary
electron monitors for high intensities up to the maximum of 10^11 pps.
While the plastic scintillators count directly the number of particles,
the ionization chambers are used in a DC mode: The number of extracted
ions is determined by the current of secondary ion-electron pairs produced
in a 80 % Ar and 20 % CO_2 gas mixture. The yield of charge from these
chambers will be compared to energy loss calculations. The signal from
the secondary electron monitors (SEM), which are made of three 100 um bent
Al foil, is proportional to the specific energy loss. The device is also
driven in a DC mode. The precision of these three devices will be discussed.
For high ion currents in the order of 10^9 pps the ionization chambers
starts to saturate due to recombinations in the plasma of secondary charges.
These limitations are compared to the non-saturatable SEM-device and will
be also presented.
MOP11 Evaluation of the Evolution of Secondary Emission Coefficients
G. Ferioli, R. Jung - CERN
Secondary Emission Monitors are used since many years in the SPS transfer
lines for the measurements of profile, position and absolute intensity
of proton beams. Important changes, up to 50% in the Secondary Emission
Coefficients (SEC) have been observed over the years in the foil region
where the beam impinges. A series of tests have been performed with different
types of foils: Al, Ti, Au, Al+Au, Ti+Au. The foils have been exposed to
a large integrated number of particles, more than 1x10 20 p/cm2 over two
years, and their SEC measured regularly to follow its evolution. The SEC
has also been calibrated once with the foil activation technique. The experimental
results of the calibration and the long-term stability of the SEC of the
various foils are presented.
MOP12 Beam Diagnostics at LNS
A. Rovelli, G. Ciavola, G. Cuttone, P. Finocchiaro, G. Raia - INFN-LNS; C. De Martinis, D. Giove - INFN-LASA
An overview of the beam diagnostics activity at LNS is presented. Devices
based on different techniques have been developed for the heavy ion accelerator
facility in order to measure the beam properties in the transverse plane;
they cover the energies range 100 keV/n - 100 MeV/n and the intensities
range 10e14 - 10e5 pps. Scanning wires and fluorescent screens are routinely
used along the beam lines and inside the cyclotron. Moreover, we will report
the results of the research activity on developing non destructive diagnostics
devices (mainly for low intensity beams) based on micro channel plates
coupled to a phosphorous screen and on micro strip gas chamber.
MOP13 Bunch Length and Phase Shift Measurements on DAFNE Accumulator
A. Ghigo, R. Boni, A. Drago, A. Gallo, F. Marcellini, M. Migliorati, F. Sannibale, M. Serio, A. Stella, G. Vignola, M. Zobov - INFN-LNF
The bunch length and the synchronous phase shift vs. the beam current
were measured in the DAFNE accumulator ring. These measurements allow to
estimate the real and immaginary part of the machine impedance respectively.
The bunch shape measurements were performed picking up the beam signal
from one 50 Ohm matched stripline and digitizing the strip signal by a
oscilloscope having a rise time of 17.5 psec. The synchronous phase shift
was measured with a Spectrum/Network Analyzer. A sample of the cavity voltage
and the longitudinal beam signal from stripline has been sent to the instrument.
The amplitude of the ratio of these signals vs. time gives the beam current
decay, while the phase gives a measurement of the synchronous phase shift.
The results of the measurements and their analysis, comparing the results
with numerical simulations based on the Accumulator ring wake field estimates,
are presented.
MOP14 DAFNE Linac Beams Characterization
F. Sannibale, G. Di Pirro, F. Marcellini, M. Vescovi - INFN-LNF
DAFNE, the Frascati phi-factory, is endowed with an injector system
composed by a 60 m Linac and by the Accumulator, a 30 m long ring for phase
space damping. The Linac, that produces and accelerates up to the Main
Rings operation energy both the electron and positron beams, is now fully
commissioned. Linac beams characterization includes measurements of current,
energy, energy spread and emittance. The beam instrumentation and the results
of the measurements for both electrons and positrons are presented.
MOP15 Luminosity Measurements at LEP
E. Bravin, B. Dehning, J.-P. Ferri, A. Forsstrom, M. Merkel, G. Morpurgo - CERN; K. Ye - IHEP, Beijing, China
Fast relative luminosity measurements are vital for the optimisation
of the machine conditions needed for physics. This has been achieved from
LEP start up by means of 16 small calorimeters made of tungsten absorbers
and silicon detectors to count Bhabha events around the four interaction
points. The high counting rates are achieved by placing the monitors inside
collimator jaws which are positioned close to the beams during data taking,
thus allowing small angle observation. With LEP1 working at 45 GeV per
beam, Bhabha events could be spotted by a mere time coincidence of the
two particles e+ and e- observed on both sides of the collision points.
The rate of fake coincidences, recorded from single background measurements,
was subtracted to correct the result. At LEP2 energies (>92 GeV) the
signal to noise ratio becomes too small for this procedure to be followed
and more sophisticated cuts (using the collinearity of Bhabha events) have
to be implemented with the help of additional silicon strip detectors placed
inside the calorimeters. The setup of the monitors and first results will
be presented.
MOP16 Absolute Measurements and Analysis of nA-Ion Beams
A. Peters, H. Reeg, C. Schroeder - GSI, Darmstadt, Germany; W. Vodel, H. Koch, R. Neubert - Friedrich-Schiller-Universitaet, Institut fuer Festkoerperphysik, Jena, Germany
Measuring function of the CCC-detector aims at the analysis of the beam's time structure to get information about beam spill fluctuations. With an extended bandwidth (0 - 20 kHz) of the detector system it is now possible to compare simulations [2] of extracted beams from synchrotons with measurements of the CCC. Furthermore a proposal for an improved version of the CCC with an enhanced slew rate of the electronics, an independent liquid helium supply and a complete remote control for the detector system will be discussed. References:
[1] I.K.Harvey, A precise low temperature dc ratio transformer, Rev. Sci. Instrumen., Vol. 43, p. 1626, 1972
[2] M.Pullia, Time Profile of the Extracted Spill, in: Proton-Ion Medical
Machine Study, CERN-Report, September 1996.
MOP17 Prospects for Improving the Performance of DC Beam Transformers
P. Odier - CERN
The two most important properties of a dc beam transformer are resolution
and drift. The greatest obstacles in achieving best possible performance
are noise in the dc BT's various components and spectral impurity of the
modulator signal. A new modulator was therefore developed, of great spectral
purity, with particular weight on minimizing the even harmonics. So far,
this has already led to reductions in initial drift (during the first hours
after turn-on), in drift caused by temperature variations, and in very-low
frequency noise. Other sources of drift and noise, formerly masked by the
modulator's imperfections, have now become apparent, and will be the target
of further studies and improvements.
MOP18 Recent Developments for Beam Intensity Increase at GANIL (THI Project)
Eric Petit, Christophe Jamet - GANIL
As part of beam intensity increase operation, new developments have
been required in instrumentation domain. Among them we can note a beam
profile called spiral scanner, a beam losses system detection to protect
accelerator and a new ejection probe to tune the beam at the ejection of
first cyclotron. Future goal is to equip accelerator of a non interceptive
beam power measurement system.
MOP19 Efficiency and Fast Spill-Measurements in the COSY Extraction
H. Labus, J. Dietrich, N. Dolfus - Forschungszentrum Julich GmbH, Germany
Combinations of a Multi Wire Proportional Chamber with a ionization
chamber or scintillator detector, respectively, are described to qualify
the extracted COSY beam. There are two major informations concerning beam
intensity, its time structure and its absolute value which is necessary
for extraction efficiency measurements. Typical spill measurements are
presented.
MOP20 Fast Measurement of Lifetime Changes and Beam Losses in DORIS by the Use of Bremsstrahlung from a Collimator
O. Kaul, B. Sarau, K. Wittenburg - DESY Hamburg
The synchrotron radiation source DORIS has typical beam lifetimes of more than 20 hours at beam currents of up to 100 mA. Very stable beam conditions are desired from the radiation users. The beam loss rate give a fast response of even very small changes of the beam parameters. By adjusting a pair of collimators close to the beam, all particals which are going to be lost will be scraped at this location. The detection of the high energy spectrum of the Bremsstrahlung created in the collimator jaws allows a high efficient detection of the total loss rate in the ring without additional background from the intense synchrotron radiation. First measurements will be presented.
TUP1 A New Method for Ultra-Short Electron
Bunch Shape Measurement Using Synchrotron Radiation from A Bending Magnet
J. Krzywinski - Institute of Physics, Polish Academy of Sciences and DESY; E.L. Saldin, E.A. Scneidmiller - Automatic System Corporation, Samara, Russia; M.V. Yurkov - Joint Institute for Nuclear Research, Dubna, Russia
A new, non-destructive method of determination of longitudinal profile
of subpicosecond electron bunches is proposed. The method is based on the
measurement of spectral intensity correlation in synchrotron radiation.
Statistical properties of the radiation from short electron bunches are
considered. Signal to noise ratio is analyzed in terms of the degeneracy
parameter equal to average number of detector counts that occur in a single
coherence interval of the incident radiation. The degeneracy parameter
roughly increases as a third power of the wavelength which makes the visible
range of synchrotron radiation to be a natural choice for the spectral
intensity correlation measurement. An example of experimental set-up is
also described.
TUP2 OTR Measurements at the ELETTRA LINAC
M. Ferianis, G. D'Auria, C. Rossi, Sincrotrone Trieste, Italy; D. Giove, C. De Martinis - INFN-LASA; A. Variola - LAL CLS
A new and very promising diagnostic technique for electron Linacs is
based on the observation of Optical Transition Radiation (OTR). ELETTRA
is a third generation synchrotron light source in Trieste in operation
since 1993. It is provided with a LINAC as an injector to the Storage Ring.
In collaboration with the LASA (INFN-MILAN) a first OTR measurement station
has been set-up on the 100 MeV LINAC section of the ELETTRA LINAC. In this
paper, the measurement station and the first observations made are presented.
OTR was observed at different electron beam energies (from 30 MeV to 100
MeV) and the variation of the spatial distribution with energy analyzed.
Future developments include further observations of the OTR emitted at
100 MeV with different kind of sensors as well as the set-up of a similar
station at higher energies to study its use as an on-line energy measurement.
TUP3 Photon Beam Position Monitors at DORIS
M. Seebach - DESY Hamburg
At DORIS both Insertion Device Beamlines and Bending Magnet Beamlines
have been equipped with new photoemission beam position monitors during
the last years. The monitors offer a resolution of few microns and a high
intensity range of more than 1000. The function of the monitors has been
improved several times by alteration of mechanical design and change of
materials. The monitors, their electronics and the latest experiences are
described.
TUP4 Bunch Phase Distribution Monitoring with Subpicosecond Resolution
Alexander M. Tron - MEPhI, Russia
Methods of longitudinal bunch charge distribution monitoring with subpicosecond
resolution using incoherent electron bunch radiation in the form of visible
light or bremsstrahlung and also secondary electron one are considered
and compared. Main restrictions on the resolution inhering in the above
mentioned techniques and possible ways of their overcoming will be presented
too. Work supported by RFFI.
TUP5 Status of the DELTA Synchrotronlight-Monitoring-System
K. Wille, Ulf Berges - Insitute for Acceleratorphysics/ University of Dortmund, Germany
A synchrotron radiation source needs an optical monitoring system to
measure the beam size at different points of the ring with high resolution
and accuracy. The first measurements with the present synchrotronlight-monitor
show that beam sizes greater than 400um can be measured. The measured emittance
is of the order of the theoretical values of the actual optics. At the
moment the resolution is not sufficient for smaller beamsizes, especially
concerning the vertical beamsize and the low emittance optics. The image
processing system which is based on a VME Framegrabber makes a gaussian
fit to the images from different synchrotronlight-monitors. At the moment
it is planned to operate with a higher and variable magnification to improve
the resolution of the system and to measure beam sizes down to 100 um,
so that it is furthermore possible to get an optical image of the beam
in the control room. To measure small sizes, especially in the vertical
plane, it is planned to use special diffraction elements and monochromatic
components of the synchrotronradiation. In addition to the imaging system
it is planned to measure the beam current and lifetime using a photodiode.
In this paper the present installation and first measurements will be reported.
TUP6 Ionizing and Optical Technique of Accelerated Ions Beams Diagnostics
A. A. Voronin, A. M. Voronin - Physics-Technical Institute, Ministry of Science, Academy of Sciences of the Republic of Kazakhstan, Alma-Ata, Kazakhstan
There were considered uncontact systems of diagnostics of low and mean
energy ion beams. They effectively allow to measure the time and spacial
characteristics of beams. Ionizing and optical detectors were studied as
primary converters on the isochronous cyclotron. Their design are given.
The ionizing profilemeter is constructed on the basis of electron-to-photon
converter with television pickup and its digital processing. Detectors
are placed along the ion pipe. The precision of coordinate measurement
is 0.1 mm when the picture size is 63 mm. x 43 mm. In the optical technique
there were used the probe made of cerium glass 25 mcm in diameter. It scans
ion beam across ion pipe. With the help of two detectors placed behind
and in front of bending magnet there can be determined not only beam profile
but time structure of accelerated ions bunch, energy and energy scattering
of isochronous cyclotron. The time resolution is 0.2 ns.
TUP7 Measurements of TTF Beam Characteristics Using Transition Radiation
R. Chehab , K. Honkavaara, M. Taurigna Quere, A. Variola - Laboratoire De L'Accelerateur Lineaire (L.A.L)
TESLA TEST FACILITY is a superconducting Linac realised by a collaboration
between American, French,German and Italian laboratories in order to study
the features of a possible future superconducting linear collider project.
In the commissioning phase of the 10MeV injector a large utilisation of
OTR diagnostics was performed, allowing a deep analysis of the beam dynamics
characteristics. With different experimental set up it was possible to
determine the 2D beam size and so the transverse emittance as well as the
bunch length using a streak camera. Special attention was also dedicated
to the analysis of the beam characteristics inside the macropulse selecting
time slices of one microsecond. We present here the results of all these
measurements together with the description of the instrumentation.
TUP8 Electron Bunch Length Monitors for the TESLA Test Facility Linac
Klaus Hanke - DESY for the TESLA collaboration
Coherent transition radiation from picosecond electron bunches can be
used for bunch length measurement. This is done by spectroscopy at wavelengths
of several millimeters. For the TESLA test facility linac, two types of
spectrometers have been developed and built. They use a photo-acoustic
detector for detection of the radiation. As an alternative, the use of
a Josephson junction as a spectrometer for millimeter waves and its possible
application for bunch length measurement is evaluated. It works at low
radiation intensity and has the potential of a fast, non-destructive measurement.
TUP9 Testing System for Relativistic Electron Beam Steering Configurations
F. Scarlat - Institute of Atomic Physics, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania
The verification of some new ideas or proposals for relativistic electron
beam (REB) steering device configurations imply the construction of a testing
system (TS) in order to choose one of them or for collecting experimental
data. This paper presents a TS based of the existing 30 MeV cyclic induction
accelerator in the Institute of Atomic Physics (IAP) supplying REBs with
energy between 3 MeV and 25 MeV. The presented schemes permit to study
of the following devices: different fotoelectric injector optics for a
free electron laser (FEL), the Smith-Purcell FEL in relativistic regime,
Cherenkov FEL, Laser Synchrotron Source and a novel FEL in ion-focused
regime using plasma or laser guiding.
TUP10 Characteristics, Uses and Developments of the Photon Counting System at the SRS
Hywel Owen - CLRC Daresbury Laboratory, Warrington, UK
The visible optical diagnostic station on the SRS electron storage ring
at Daresbury Laboratory includes a time-correlated single photon counting
system based around a Philips XP2020Q photomultiplier tube. The detection
electronics are described together with a discussion of system choice,
setting up, noise behaviour, overall system speed and resolution. Computer
control and analysis of the collected multichannel analyser data is performed
using a PC linked to the main accelerator control system. This is used
to make two principal measurements: firstly, contamination levels during
single-bunch running of the storage ring, and secondly, the measurement
of fill structures in the two modes of multibunch running - uniform filling
of the bunches in the storage ring and gapped fill structures. Sample data
are given and discussed. The options for future development are debated.
TUP11 A New Tune Measurement System for the HERA Proton Ring
J. Klute - DESY Hamburg
Knowledge of the betatron frequencies is essential for operation of
storage rings. There are various techniques to measure the betatron tunes
according to the type, requirements and mode of operation of an accelerator.
In general, the beam must be externally excited because of either the absence
of inherent oscillations or it is damped by a feedback system. Beam excitations
are, on the other hand unwanted especially in the case of proton machines
due to the resulting emittance growth. Under consideration of these aspects
a sophisticated Tune Indicator has been developed and put into operation
for the HERA proton ring. The device provides a continuous and fast tune
measurement at high accuracy (typ. 4e-4 ) and is therefore suitable to
determine other tune related parameters. It is integrated in the multibunch
feedback environment and gives the possibility of measuring the tunes even
while the feedback system is damping the beam. The method of operation
is described on this poster.
TUP12 Dynamical Tune Measurements at COSY-Julich
J. Bojowald, J. Dietrich, I. Mohos - Forschungszentrum Julich GmbH, Germany
Different methods for tune measurements in the COSY ramp are described
and compared. The tune is measured with proper beam excitation and a) by
conventional two channel spectrum analyser using iterative measurements
for getting the transversal and longitudinal lines at the same time in
the spectra; b) by network analyser in zero span mode and determining the
instantaneous revolution frequency from the digital data of the rf-system;
c) by conventional synchronized kick excitation of the beam; d) by automatic
tracking of the betatron frequency (tunemeter) and e) by a more sophisticated
automatic tunemeter method with bunchsynchronous signal recording and FFT
analysis.
TUP13 A Low Noise Detector for Transverse Beam Oscillations
D. Heins, J. Klute, R.D. Kohaupt, K.H. Matthiesen, S. Paetzold, J. Theiss - DESY Hamburg
Transverse beam oscillation detectors are needed in beam diagnostics,
feedback systems and tune measurement for example. Especially in proton
feedback systems low noise equipment is absolutely necessary in order to
avoid beam emittance growth. The highest possible signal power is gained
by using the full beam position pickup signal bandwidth. Peak detectors
fully utilize this total available signal power and provide therefore high
sensitivity. Only after detection the bandwidth is limited to a suitable
degree. According to the bunch spacing of 96 ns the detector generates
a 10.4 MHz rated bunch deviation signal which is digitized by a 12 bit
A/D converter. A special offset compensation loop using digital signal
processing technology eliminates the individual DC offset of each bunch.The
described peak detector is used in the multibunch feedback of the HERA
proton ring and feeds the tune indicators, as well.
TUP14 A System for the Fast Detection of Longitudinal Instabilities Caused by the RF Cavities Hom on the Esrf Storage Ring
J.M. Koch, E. Plouviez - ESRF, Grenoble, France
The 353.2 MHz RF cavities of the ESRF storage ring have higher order
modes of resonance(HOM) at about 500 MHz and 900 MHz. These modes can cause
longitudinal instabilities on the beam and result in partial or even total
beam loss. The unambiguous identification of these incidents required a
good understanding of the instability physics, a good skill in the handling
of a spectrum analyzer and some luck. For these reasons a special HOM detector
has been designed and implemented at the ESRF. The signature of a HOM instability
on the beam signal is the presence of synchrotron sidebands around a limited
number of high order harmonics of the beam revolution frequency. We have
developed an automatic detection system based on an optimized superheterodyne
receiver. A fast frequency hopping synthesizer allows the fast scanning
of the frequencies of interest. For each frequency step, a spectrum is
computed by a DSP running an FFT algorithm. We describe in detail the principle
of beam signal analysis performed by our system, and present data obtained
using this diagnostic both during machine physics run and operation.
TUP15 RF and Baseband Signal Processing functions in the PEP-II/ALS/DAFNE Longitudinal Feedback System*
A. Young, J. Fox, D. Teytelman, and I. Linscott - SLAC
The PEP-II/DAFNE/ALS feedback systems are complex systems requiring
analog, digital and microwave circuits. The front-end (beam motion detection)
and back-end (kicker signal modulator) functions are implemented using
VXI hardware which allows flexible system control via the EPICS control
system. The front-end module produces a baseband beam phase signal from
BPM pickups using a microwave comb generator. The back-end VXI module generates
an AM/QPSK modulated signal from a baseband correction signal computed
in the digital signal processing modules. The VXI implementation allows
mixed RF and digital functions in a single module and includes a system
operational and diagnostic functions such as 120 MHz bandwidth rms detectors
(for beam motion and kicker drive monitoring), attenuators, reference phase
servo, woofer link to the RF control system, standard VXI status/control,
and user defined registers. The details of the architecture, design and
implementation of the VXI modules are presented, as are operational results
from the PEPII and ALS system installations.* Work supported by Department
of Energy, contract DE-AC03-76SF00515
TUP16 Status of the DELTA Betatron-Tune-Monitoring-System
K. Dunkel, K. Wille - Institute of Accelerator-Physics/ University of Dortmund, Germany
The booster Bodo of the storage ring facility DELTA is a ramped storage
ring. Due to the low repetition rate of about 0.1 Hz the losses during
an acceleration cycle must be as low as possible. Therefore the betatron
tunes must be measured and kept constant during acceleration. With the
present installation recording the tune every 50 msec with a solution <1
percent is possible. The system consists of only a few analog electronic
circuits; a spectrum analyser is not necessary. Either an oscilloscope
or a computer read out is used to make the data available to the operator.
In this paper the present installation, results and future applications
will be reported.
TUP17 Operational Experience with Transverse Coupled Bunch Feedback in the ALS
John Byrd, Walter Barry - LBNL
The ALS has been operating at 400 mA total beam current in about 300
bunches with a spacing of 2 nsec for over 2 years. We present a summary
of our operational experience with the transverse coupled bunch feedback
system. We describe the diagnostics and techniques which have been used
to optimize system performance and how the system is used to study the
dynamics of beam instabilities. We also discuss a configuration of the
system which has been used to damp the single bunch mode coupling instability
in the vertical direction.
TUP18 KEKB Bunch Feedback Systems and Related Systems
Eiji Kikutani, M. Tobiyama - KEK, High Energy Accelerator Research Organization
A B-factory project at KEK, named KEKB, is now under construction. It consists of energy-asymmetric two rings. It is expected that strong coupled bunch instabilities will occur due to very high currents. To cure them we are planning to install powerful bunch feedback systems in both longitudinal and transverse planes. The construction of the feedback systems is now under way. We report the status of the construction of these feedback systems and related systems, such as a tune meter, bunch position memory systems.
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