Title: Flexible bearings for high precision positioning and
stabilization
S. Henein, CSEM
This paper presents flexible bearings and how they can be used in high precision positioning or stabilization mechanisms, highlighting their compatibility with vacuum and cryogenic environments. Flexible bearings are mechanical linkages just like conventional bearings. In the latter, linkage is assumed by friction or a rolling motion between two solid bodies. Flexible bearings on the other hand depend on the elastic properties of matter. Many advantages are derived from this approach: no friction, no wear, no lubrication, no backlash, no risk of jamming, high stiffness. Combined with adequate non-contact actuators and sensors they allow to reach nanometric positioning resolutions. These mechanisms are perfectly well suited to the precise positioning of a large variety of components which are used in particle-beams or synchrotron facilities. The basis of a design methodology of flexures is presented in the first part of the paper. The method covers simple 1 degree of freedom bearings as well as complex mechanical structures having up to 6 degrees of freedom. In a second part, several examples of mechanisms which have been developed at CSEM for space and astronomical applications are presented.
Title: Circular accelerator low level Radio Frequency feedback loops
E. Onillon, CSEM
This paper presents an approach of designing feedback loops for a circular particle accelerator with low level Radio Frequency (RF). It includes phase, radial feedback loops as well as synchronization loops between an injector and the main accelerator. The feedback design is based on a state space approach. A state space model linking the main variables typically used to describe a RF system is introduced before presenting the feedback design.
Title: Simulation of Laser-wires at the Linear Collider
G.A.Blair, Royal Holloway, Univ. of London
Compton scattering of laser light of electron bunches in the beam delivery system of the linear collider provides a promising method to measure the transverse electron bunch size. Detection of the scattered photons and electrons from the beamline requires careful design and optimisation. First simulation of these issues are presented using Geant4 techniques.
Title: A plan of ATF Final Focus Test Beam Line
Your-Name, Your-Institute S.Kuroda, J.Urakawa, T.Okugi, K.Kubo, T.Tauchi/KEK
Your Abstract We have been done a simulation to get 50nm flat beam using extracted beam from the ATF. Detail design and beam tuning method will be discussed.
Title: Experimental Study of Laser-Compton Scattering in Non-linear
Regime
Y. Kamiya, Tokyo Metropolitan University T. Kumita, Tokyo Metropolitan University
S. Kashiwagi, Waseda University T. Hirose, Waseda University M. Washio, Waseda University
T. Omori, High Energy Accelerator Research Organization (KEK) J. Urakawa, High Energy Accelerator Research Organization (KEK) K. Yokoya, High Energy Accelerator Research Organization (KEK)
Ilan Ben-Zvi, Brookhaven National Laboratory Karl Kucshe, Brookhaven National Laboratory Igor Pogorelsky, Brookhaven National Laboratory Peter Siddons, Brookhaven National Laboratory Vitaly Yakimenko, Brookhaven National Laboratory
We have performed an experiment for generating high brightness X-ray via Compton scattering of 60MeV electron beam and high power CO2 laser at the Accelerator Test Facility in Brookhaven National Laboratory. This is one of the approaches to compact light sources utilized for various fields such as biology, biochemistry and high energy physics.
In near future, our CO2 laser will be upgraded and the power will reach to 1 TW. We expect to observe non-linear Compton scattering of the electron and laser beams in this situation.
In this talk, we give an overview of the experiment and describe a two- dimensional x-ray spectrograph designed to monitor energy spectrum and angler distribution of x-rays for each pulse.
Title:
Your-Name, Your-Institute
Your Abstract
Title: Charged Particle Storage Ring as Detector of Gravitational
Waves
Dong Dong, Huang Chao Guang, Institute of High Energy Physics, Chinese Academy of Sciences
Your Abstract
Title: E-beam stabilization experiences at the ESRF
L Zhang, L Farvacque European Synchrotron Radiation Facility
Since the construction and operation of the ESRF, great efforts have been made to improve the e-beam stability. These include ground vibration measurements, internal and external vibration sources identification and elimination, girder design optimisation, development and implementation of vibration damping system for magnet girder assembly, investigation of fluids induced vibration. These achievements on mechanical vibration are very benefit for the machine and e-beam stabilisation. Global and local feedbacks have been also implemented. Significant improvement on e-beam stability is achieved.
Title: Development of Soft X-ray Source using Laser Compton Scattering
R. Kuroda/Waseda University, S. Kashiwagi/Waseda University, M. Washio/Waseda University, T. Hirose/Waseda University, J. Urakawa/KEK, H. Hayano/KEK
Development of pulsed soft X-ray source has been started at Waseda University. The soft X-ray pulse is generated via laser Compton scattering between a pico-second electron beam and a pulsed laser beam. The pico-second electron beam is produced by a photo-cathode rf gun and the energy of the electron beam is about 5 MeV. The pulsed laser beam is obtained from an all-solid state Nd:YLF laser, which has a fundamental wavelength of 1047 nm(IR). By the laser Compton scattering between the 5 MeV electron beam and the IR laser, it is possible to generate soft X-ray pulse in the water-window energy region (200 to 500 eV). This soft X-ray is very useful tool for an X-ray microscopy. It will be applied to the biological observation. In this workshop, our system for the soft X-ray generation and preliminary results of beam experiments will be described.
Title: The ESRF HLS - Twelve Years Experience With a Large Scale
Hydrostatic Leveling System
Martin, David ESRF
The European Synchrotron Radiation Facility (ESRF) located in Grenoble France is an accelerator laboratory producing high quality x-rays for use by scientists from Europe and around the world. Alignment tolerances are typically less than 1 mm and often in the order of several micrometers over the approximately 844 m circumference. To accommodate these tolerances, a high quality hydrostatic leveling system (HLS) was conceived and installed on the principal accelerator -the Storage Ring- during the construction of the facility. This system is composed of 288 devices (HLS pots and captors) installed on 96 magnet supports evenly distributed around the ring. It has a resolution of better than 1 µm and a precision in the order of the micron (over the period of several hours). This paper will discuss the ESRF experience with this system since it's installation in 1991.
Title: Vibration Control Feedback R&D at University of British
Columbia
Thomas Mattison University of British Columbia
Our group is developing sub-nanometer vibration measurement and control technology for future linear colliders. We use laser interferometry, capacitive displacement sensors, or geophones for position measurement, and piezoelectric actuators for position control. We have been pursuing the "Optical Anchor" concept of using feedback to artificially stiffen a support system, using a one-degree-of-freedom horizontal test fixture. Results and lessons-learned will be presented.
Title: Plans and Priorities for the CLIC Stability Study
R. Assmann
The CLIC stability study aims at demonstrating the feasibility of nano-metre size colliding beams, as they are foreseen for the CLIC design. The plans and priorities for future work are shortly presented.
Title: Results from the CLIC Stability Study
R. Assmann, W. Coosemans, G. Guignard, N. Leros, S. Redaelli, W. Schnell, D. Schulte, I. Wilson, F. Zimmermann, CERN
The CLIC stability study has set-up a test-stand on the CERN site to study magnet vibrations in the nanometre regime. The measurements achieved with and without advanced stabilization equipment are presented.
Title: The Effect of Cooling Water on Magnet Vibrations
R. Assmann, W. Coosemans, S. Redaelli, W. Schnell, CERN
The effect of cooling water on CLIC prototype quadrupoles has been quantified in the nanometre regime. The measurements and their analysis are presented.
Title: Orbit Control at the SLS Storage Ring
M. Böge, J. Chrin, P. Pollet, T. Schilcher, V. Schlott Paul Scherrer Institute (PSI), Villigen, Switzerland
Precise orbit control is one of the crucial ingredients for stable operation of the SLS storage ring. A digital BPM system measures the orbit with sub-micron resolution at sampling rates of up to 4 kHz at 72 locations in the ring. Orbits are corrected with respect to a user defined reference by applying SVD techniques and a direct response matrix inversion. A slow global orbit feedback operating at correction rates of up to 1 Hz stabilizes the orbit to within ~0.5 micrometer RMS at the locations of the insertion devices. Energy drifts are automatically corrected using the RF frequency as an additional corrector, thus providing a long term energy stability of dE/E = 2e-5. Operational results are presented along with the status of the upgrade to a fast orbit feedback running at 4 kHz sampling rate.
Title: Requirements to beams sizes at photon colliders and problems of
realization
Valery Telnov/Budker INP and DESY
Photon colliders in sub-TeV energies can work with beam sizes much smaller in e+e- collision (especially in horizontal direction). At present, there are no beam sources with adequate emittances, beside, existing final focus systems can not focus electron beams to their natural limits due to chromo-geometric aberration. Solution needs joint efforts. In the talk the problem is formulated and some ideas are discussed.
Title: Measurement of the absolute energy at LC using spin precession
Valery Telnov, Budeker INP and DESY
Measurement of electron beam polarization before and after bend at various directions of spin vector at the entrance of linac allows to deteremine the beam energy with a high accuracy
Title: Ground Motion Activities at DESY - An Overview
Christoph Montag, BNL
Ground motion studies have been performed at DESY for more than a decade, covering beam motion in the two-ring e-p collider HERA, luminosity preservation in Linear Colliders, and active stabilization methods. An overview of past and present activities will be given.
Title: Observation of Mechanical Triplet Vibrations in RHIC
Christoph Montag, BNL
Mechanical vibrations of the RHIC IR triplets has been identified as the dominant source of horizontal orbit jitter in the frequency domain below 20 Hz. Results of detailed measurements will be reported that were performed to characterize these effects.
Title: 2002 Results from FNAL MI-8 and Aurora mine ground motion
experiments
V.Shiltsev, D.Plant, J.Lach /FNAL A.Chupira, A.Erokhin, M.Kondaurov, A.Medevedko, S.Singatulin, E.Shubin / BINP A.Kuznetsov/NSU, A.Seryi/SLAC
We present status and recent results from two slow ground motion experiments for FNAL future collider projects: an underground experiment in Aurora dolomite mine and in MI-8 injection line tunnel.
Title: Magnet vibrations and orbit motion in the Tevatron
V.Shiltsev, X.L.Zhang, T.Johnson /FNAL
We present results of recent observation and measurements of baem orbit and magnet vibrations in the proton-antiproton collider Tevatron.
Title: Linearizing Intra-Train Beam-Beam Deflection Feedback
Stephen R. Smith, Stanford Linear Accelerator Center
Beam-beam deflection feedback acting within the crossing time a single bunch train may be needed to keep linear collider beams colliding at high luminosity. In a short-pulse machine such as the Next Linear Collider (NLC), with bunch trains only 250 ns-long, this feedback must converge quickly to be useful. The non-linear nature of beam-beam deflection vs. beam-beam offset in these machines precludes obtaining both rapid convergence and a stable steady-state lock to beam offsets with a linear feedback algorithm. High gain is needed at large beam-beam offsets to get rapid convergence, but then the increasing slope of beam-beam deflection curve at small offsets leads to instability when approaching head-on collisions. We show that a simply realizable programmable non-linear amplifier in the feedback loop can linearize the feedback loop, approximately compensating the beam-beam deflection non-linearity. Performance of a prototype non-linear amplifier is shown. Improvement of convergence and stability of the beam-beam feedback loop is simulated.
Title: The method of temperature compensation for permanent magnet
final focus quadrupole
session: no
Evgeny Antokhin, BINP
The method for decreasing temperature dependence of magnetic field of pure permanent magnet magnets is suggested to application for final focus quadrupole of Japanese Linear Collider. The method is based on using two permanent magnet materials with different temperature coefficients of remanence field. It is possible to decrease by such way the temperature dependence of magnetic field of permanent magnet quadrupole in factor more than 50. The design of final focus quadrupole with temperature compensation is described.
Title: Beam-Beam Scans within a Bunch-Train Crossing at a Linear
Collider
session: 7 - Tuning, Feedback, Diagnostics
Stephen R. Smith, Stanford Linear Accelerator Center
Beam-beam deflection scans provide an important beam diagnostic at the interaction point of a linear collider. Beam properties such as spot sizes, alignment, and waists are measured by sweeping one beam across the other. Proposed linear colliders use trains of bunches; if beam-beam scans can be done within the time of a bunch-train crossing rather than integrating over the bunch train, the acquisition rate of diagnostic information can be dramatically increased and the sensitivity of the scan to pulse-to-pulse jitter and slow drifts can be dramatically reduced. The existence of intra-train deflection feedback provides most of the hardware needed to implement intra-train beam-beam scans for diagnostic purposes. A conceptual design is presented for implementation of such a fast diagnostic beam-beam scan.
Title: CLIC Damping Ring Status Report
session: 8 - Generation Low Emittance Beams
Maxim Korostelev, CERN, Geneva, Switzerland
Intense bunches injected into the main linac of Compact Linear Collider (CLIC) must have unprecedentedly small emittances to achieve the design luminosity. The positron and electron bunch trains will be provided by the CLIC damping ring complex. Damping-ring design parameters for CLIC are optimized by taking into account the combined action of radiation damping, quantum excitation and intrabeam scattering. We present a ring optics which provides such low-emittance beam.
Title: CLIC Damping Ring Status Report
session: 8 - Generation Low Emittance Beams
Maxim Korostelev, CERN, Geneva, Switzerland
Intense bunches injected into the main linac of Compact Linear Collider (CLIC) must have unprecedentedly small emittances to achieve the design luminosity. The positron and electron bunch trains will be provided by the CLIC damping ring complex. Damping-ring design parameters for CLIC are optimized by taking into account the combined action of radiation damping, quantum excitation and intrabeam scattering. We present a ring optics which provides such low-emittance beam.
Title: Permanant Magnet Quadrupole Lens with Variable Strength
session: 2 - Beam delivery, Final Focus, Collimation
Y. Iwashita, Kyoto University, Japan
Permanant Magnet Quadrupole Lens is one of the candidates for the final focus lens, because of its compactness and less power consumption, while one drawback is its fixed strength. We can change the total strength of the lens by rotating subdivided pieces separately. The mechanical scheme will be discussed.
Title: Feedback Experience in the SLC and PEPII
session: 7 - Tuning, Feedback, Diagnostics
Linda Hendrickson, Nan Phinney /SLAC
Feedback systems were essential to the successful operation of the SLC. We discuss the operational considerations, generalized design and implementation of the system, in addition to performance results and discussion of limitations. We present the algorithms and design response for the IP beam-beam deflection feedback loop and for the luminosity optimization feedback system. Finally, if there is time, we may briefly cover how the SLC feedback system was adapted to stabilize the orbit and collisions for the PEPII collider.
Title: Algorithms and Simulation Results for NLC IP and Linac Feedback
Systems
session: 7 - Tuning, Feedback, Diagnostics
Linda Hendrickson/SLAC
In planning for 120-Hz train-by-train feedback systems in the NLC, we have used the SLC feedback system as a model. Recent studies for NLC have focused on evaluation of improved algorithms. This talk will describe proposed designs for both the linac and IP beam-beam deflection feedback systems. It will include results of both simulations and prototype testing. We hope to allow time for discussion of interactions between feedback systems on different timescales.
Title: Vibrational Stability of NLC Linac and Final Focus Components
session: 3 - Stabilization
F.~Le~Pimpec, S.~Adiga (Stanford Univ.), F.~Asiri, G.~Bowden, D.~Dell'Orco, E.~Doyle, B.~McKee, A.~Seryi SLAC
Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structure and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. Design to properly decouple the structure vibrations from the linac quadrupoles is being pursued.
Title: epac
session: 2 - Beam delivery, Final Focus, Collimation
Redaelli Stefano, CERN / University of Lausanne
Your Abstract
Title: Comparison of different tracking codes for beam delivery
systems of linear colliders
session: 2 - Beam delivery, Final Focus, Collimation
Redaelli Stefano, CERN / University of Lausanne
Several tracking codes for beam delivery systems of linear colliders have been compared. The case of the CLIC has been considered. The results of this comparison are presented here.
Title: Update on Banana Simulations
session: no
Daniel Schulte, CERN
Simulations of the combined effect of wakefields in the main linac and beam-beam interaction at the interaction point (the so-called banana effect) have shown that significant luminosity loss can result even from a very small emittance growth in the linac. Optimisation of the collision offset and angle significantly increases the luminosity in the presence of static errors. However dynamic errors remain problematic.
Title: CLIC Beam Delivery System
session: 2 - Beam delivery, Final Focus, Collimation
F. Zimmermann, R. Assmann, H. Burkhardt, S. Redaelli, T. Risselada, D. Schulte, CERN; A. Faus-Golfe, IFIC; G. Blair, Royal Holloway
We present an overview of the present design for the CLIC beam delivery systems at 3 TeV and 500 GeV, discuss future studies, and consider open questions.
Title: Quantum Mechanical Limits on Beam Demagnification and
Luminosity
session: 2 - Beam delivery, Final Focus, Collimation
F. Zimmermann, CERN
I review some quantum-mechanical limits on the final focus and the attainable luminosity in a linear collider.
Title: Overview of Post-Linac Collimation in Linear Colliders
session: 2 - Beam delivery, Final Focus, Collimation
Peter TENENBAUM, SLAC
The post-linac collimation system of a linear collider has to simultaneously satisfy several contradictory requirements: machine protection of downstream elements, self-protection, removal of beam halo, acceptable wakefield performance. The issues involved in these requirements will be discussed, and some examples of managing the tradeoffs will be presented.
Title: Dr
session: 4 - Interaction Region
Helmut Burkhardt, CERN
Muon background simulation and Geant4
The process of gamma conversion into a pair of muons has recently been added as standard process to the Geant4 program. The main features of the process and the potential of Geant4 for combined machine/detector background simulations will be described.
Title: Instrumentation Development - Test Facilities and Plans
session: 7 - Tuning, Feedback, Diagnostics
Marc Ross, SLAC
Development and testing of precision instrumentation has been centered at KEK-ATF and FFTB. Design efforts include RF sub-micron resolution position monitors for use in the linac, micron resolution laserwire profile monitors for use in the linac and damping ring, sub-millimeter resolution bunch length monitors for use in the bunch compressor system and special purpose profile monitors. The task of perfecting position and profile monitors and extending their resolution for use with nanobeams near the IP is still before us. In this talk, we will review the requirements of beam instrumentation in the beam delivery and IP region and describe planned and ongoing RD efforts on these instruments.
Title: Sources for Nanobeams - a comparison between the ATF and the
NLC and TESLA designs
session: 8 - Generation Low Emittance Beams
Marc Ross, SLAC
Damping ring emittance minimization strategies are focused on correction of mechanical and magnetic errors. Since typical alignment tolerances are less than 50 microns, we expect to apply the strategy repeatedly during the life of the ring. Beam position monitors, their location and performance characteristics, will in large part determine the effectiveness of the minimization strategy. We present the results of the coupling and vertical dispersion tuning process for the three rings.
Title: Method of Correcting the LHC b* at Collision.
session: 7 - Tuning, Feedback, Diagnostics
Walter Wittmer, CERN SL/AP and University of Technology Graz
For the LHC the correction of the b* at collision with a set of related quadrupoles is refered to as a b* tuning knob. For each transverse plane a b* tuning knob has been calculated and was tested for an LHC interacton region with MAD 8. The ideas are based on previous methods from linear colliders and should therefore be applicable for future linear colliders as well. The knobs' linear behaviour and their orthogonality were studied. Different field errors were introduced into the lattice and their effects on the knobs were studied. Preliminary results are presented.
Title: Status and Plans of the Oxford LiCAS Group. (Linear Collider
Alignment and Survey)
session: 3 - Stabilization
Grzegorz Grzelak Oxford University
The automatic survey system designed to measure the co-ordinates of the external reference points located along the Linear Collider (LC) tunnel will be presented. The discussed project is currently under development at the Oxford University in collaboration with the DESY TESLA team.
It will be a modular system constructed of six 'cars' connected with the vacuum pipe to form a 'train' which is able to travel along the LC tunnel. The basic idea of the measurment relies on the Straightness Monitor composed of two laser beams, beam splitters and CCD cameras and on the Distancemeters constructed using the FSI technology (Frequency Scanning Interferometry) which makes use of the infrared tunable lasers.
Expected resolution of the measurement which could be obtained using this system is of the order of 200 microns over 600 meters.
Details of the construction, technical parameters and constrains and the planned time schedule will be presented in the talk.