07 Accelerator Technology Main Systems

T28 Subsystems, Technology and Components, Other

Paper Title Page
MOZBM01 High Intensity and Low Emittance Guns 46
 
  • P. M. Michelato
    INFN/LASA, Segrate (MI)
  
  High intensity or high-brilliance, low emittance electron beams are needed for many applications, ranging from SASE FELs to fast radiolysis systems, from Compton backscattering X ray sources to energy recovery linac, from CW FELs to the linear collider. They are produced using a high field RF accelerating structure together with a photoemissive electron source: the rapid acceleration process minimizes the space charge effects which tend to spoil the emitted beam characteristics. The talk will review the technology and provide the important parameters of these sources as the generated bunch charge, the repetition rate, the mean and peak current, the beam emittance, etc, together with an analysis of gun reliability and technological challenges. I will present the state of the art of the technology of the RF guns, either using metallic or semiconductor photoemitters. New high repetition rate/CW sources, appearing in the last years, using superconducting cavities, will be also reviewed.  
slides icon Slides  
MOZDM01 LHC Hardware Commissioning Summary 56
 
  • R. I. Saban
    CERN, Geneva
  
  The presentation summarizes the main phases of the LHC hardware commissioning and discusses especially the powering of one completer sector to the nominal current.  
slides icon Slides  
TUPC128 Air Temperature Analysis and Control Improvement for the EPU 5.6 at TLS 1368
 
  • J.-C. Chang, Y.-C. Chung, C.-Y. Liu, Z.-D. Tsai
    NSRRC, Hsinchu
  
  This paper presents the air temperature analysis and control improvement for area of the elliptically polarizing undulator EPU 5.6 in the Taiwan Light Source (TLS). To enhance uniformity of ambient air temperature, we applied mini environmental controls and installed five cross flow fans in this area. Eight temperature sensors were installed around the EPU to monitor temperature variation. We also simulated the flow field and temperature distribution in this area by using a computational fluid dynamics (CFD) code. The simulation results were validated by comparing to measured data. The temperature variation along time and spatial temperature differences were controlled within 0.1 degree C and 0.5 degree C, respectively.  
TUPC129 LHC Access System: from Design to Operation 1371
 
  • T. Pettersson, C. Delamare, S. Di Luca, S. Grau, T. Hakulinen, L. Hammouti, F. Havart, J.-F. Juget, T. Ladzinski, M. Munoz Codoceo, P. Ninin, R. Nunes
    CERN, Geneva
  
  The paper describes the LHC access control and safety system project, the system's architecture and the experience gathered of commissioning it. This system is made of two parts: the LHC Access Control System and the LHC Access Safety System. Using state of the art redundant, fail-safe PLC's and a supplementary, cabled control loop the LHC Access Safety System guarantees the safety of the personnel in all events. Using industrial components, the LHC Access Control System, regulates the access to the tunnels and experimental areas by identifying the users and checking their authorisations. It allows a remote or automatic operation of the access control equipment and restricts the number of users working simultaneously in the interlocked areas. A first implementation of the architecture is now in production and ensures that only authorized personnel can enter the controlled areas of the LHC complex and this only after permission has been given by the CERN Control Centre. The design, procurement and installation of the entire system took more than 4 years and the commissioning phase lasted about 12 months.  
TUPD019 Inter-disciplinary Mechanical and Architectural 3D CAD Design Process at the European XFEL 1467
 
  • L. Hagge, N. Bergel, T. H. Hott, J. Kreutzkamp, S. Suehl, N. Welle
    DESY, Hamburg
  
  Realising the European-XFEL involves creating and coordinating several types of 3D design models for many different subsystems like underground buildings, utilities, accelerator systems or photon beam lines. In order to handle the huge amount of data, reduced envelope models are needed for integrating the subsystems towards the complete facility and to ensure that the different subsystems connect properly and do not intersect. Detailed component design models are required for planning approval, tendering or in-house production. A key issue was to develop an optimized design for the facilities while still being able to accommodate possible late R&D-driven design changes of subsystems. The paper describes the procedures and tools which are used for planning and designing the European-XFEL and reports benefits and experience. The procedures in use allow visualization of the facilities, negotiation of requirements and solutions between all the working groups, optimized storing of the documentation as well as running approval and change management procedures. Tools in use include a requirements database, 3D-CAD systems and an engineering data management system.  
TUPD020 Remote Alignment of Low Beta Quadrupoles with Micrometric Resolution 1470
 
  • M. Acar, J. Boerez, A. Herty, H. Mainaud Durand, A. Marin, J.-P. Quesnel
    CERN, Geneva
  
  Considering their location in a high radiation environment and the alignment tolerances requested, the Low Beta quadrupoles of LHC will be positioned remotely (controlling 5 degrees of freedom), with a displacement resolution of few microns in horizontal and vertical. Stepping motor gearbox assemblies are plugged into the jacks which support the cryomagnets in order to move them to the desired position regarding the quality of the beam collisions in the detectors. This displacement will be monitored in real time by the sensors located on the magnets. This paper describes the positioning strategy implemented as well as the software tools used to manage it.  
TUPD021 Sliding Force Measurements on the LHC RF Contact Plug in Modules at 15 K and in UHV 1473
 
  • K. Artoos, M. Guinchard, T. Renaglia
    CERN, Geneva
  
  Some sliding RF contacts mounted in the Plug In Modules in the LHC interconnects failed during a thermal cycle between 4.2 K and room temperature. Gold-coated copper-beryllium RF fingers buckled during the warm up of the machine, indicating that one or more parameters during operation (e.g., the friction coefficient under vacuum) might be different from what was used in the calculations. This report describes the measurement of the longitudinal forces acting on the sliding RF fingers at operating vacuum and temperatures.  
TUPD022 Electron Beam Polarimetry at the S-DALINAC 1476
 
  • R. Barday, U. Bonnes, C. Eckardt, R. Eichhorn, J. Enders, C. Heßler, J. Kalben, Y. Poltoratska
    TU Darmstadt, Darmstadt
  • W. F.O. Müller, B. Steiner, T. Weiland
    TEMF, Darmstadt
  
  It is planned to carry out experiments at the Superconducting Darmstadt Linear Accelerator S-DALINAC with both polarized electron and photon beams at the energy of the electron beam between 10 and 130 MeV. In order to extract asymmetry from these experiments the absolute degree of the electron beam polarization needs to be known. We present the existing and planned polarimeters at the source of polarized electrons and the experimental sites, especially a 100 keV Mott polarimeter and Möller polarimeter for 15-130 MeV electrons.  
TUPD024 Results of ELBE Window and Coupler Tests with a Resonant Ring 1479
 
  • A. Buechner, H. Buettig, R. Schurig, G. Staats, A. Winter
    FZD, Dresden
  
  A new test bench based on a resonant ring has been built at ELBE to run window as well as coupler tests. The resonant ring is driven by a 10 kW klystron and allows tests with RF power up to 100 kW in CW mode and about 200 kW in pulsed mode. Coupler tests are done with liquid Nitrogen cooling under almost real conditions. The results of warm window and coupler tests in pulsed and CW mode are presented. Also details about the ring and a special designed coupler tip to rectangular waveguide transition are given.  
TUPD027 Commissioning of the Offline-teststand for the S-DALINAC Polarized Injector SPIN 1482
 
  • C. Heßler, R. Barday, U. Bonnes, M. Brunken, C. Eckardt, R. Eichhorn, J. Enders, M. Platz, Y. Poltoratska, M. Roth
    TU Darmstadt, Darmstadt
  • W. Ackermann, W. F.O. Müller, B. Steiner, T. Weiland
    TEMF, Darmstadt
  • K. Aulenbacher
    IKP, Mainz
  
  At the superconducting Darmstadt linear electron accelerator S-DALINAC a new injector for polarized electrons is under development. For this purpose an off-line test stand has been constructed. It consists of the source of polarized electrons and a test beamline including a Wien filter for spin manipulation, a Mott polarimeter for polarization measurement and various beam steering and diagnostic elements. The polarized electron beam is produced by photoemission from a strained GaAs cathode. We report on the status of this project and present first results of the measurements of the beam properties. We also give an outlook on the upcoming installation of SPIN at the S-DALINAC.  
TUPD028 How to Stably Store Electron Beam in a Synchrotron Radiation Facility from the Point of View of an RF System Design 1485
 
  • Y. Kawashima, H. Ego, Y. Ohashi
    JASRI/SPring-8, Hyogo-ken
  • M. Hara
    RIKEN Spring-8, Hyogo
  
  In any synchrotron radiation facilities, the users wish that electron beams are stably stored without beam abortion for as long as possible. It must be recognized that RF system is a main cause of beam abortions. In order to store beam stably, it is necessary for staffs in charge of RF system to foresee various beam instabilities and to take measures. Before discussing coupled-bunch instability problems, one should understand some trivial issues such as ion trapping and fundamental acceleration frequency modulated by high voltage ripple. The former causes transverse mode instability and the latter shakes stored electron beam longitudinally in RF cavities. In newly designed synchrotron radiation facilities, those issues mentioned above should be suppressed before beam commissioning. As for other issues relating with RF system, we would like to state the importance of a water-cooling system with stable temperature for cavities, and the electric earth problem of low level RF system and high voltage power equipment of a klystron. We describe how we have managed those issues in designing of SPring-8 RF system of the storage ring.  
TUPD030 Distributed Project Management at the European XFEL 1488
 
  • J. Kreutzkamp, L. Hagge, R. Wichmann
    DESY, Hamburg
  
  The European XFEL project at DESY has introduced a distributed project management system (DPMS) based on Microsoft Project Enterprise to keep track of schedules, resource usage, investment planning and actual costs. The XFEL project is organized into more than 40 work packages (WP) which address the different technical subsystems, global infrastructure and general tasks. Each WP is led by a work package leader (WPL) who is responsible for the WP budget, schedule and resources. The DPMS enables WPLs to directly create and update project plans for their WP, and it automatically creates high-level aggregated views for the project management office. Along with the system introduction, processes for distributed project planning, controlling and reporting have been established. One of the key challenges which can be resolved with the DPMS is to identify and track dependencies among different WPs, and to determine and escalate the impact of changes in one WP to other WP schedules. The DPMS is in operation since early 2007. The paper gives an overview of the system and the established project management processes and reports experience.  
TUPD031 Crystals Application in the TOTEM Experiment to Increase the Acceptance of a Roman Pot 1491
 
  • E. Laface, W. Scandale
    CERN, Geneva
  • S. Hasan
    Univ. Insubria and INFN Milano, Como
  • C. Santoni
    Université Blaise Pascal, Clermont-Ferrand
  
  Bent crystal may enhance the physics reach of a near-beam physics detector in the CERN-LHC, by increasing the acceptance of scattered protons in low transverse momentum reactions. As an example we present simulations demonstrating the increase of the Roman Pot acceptance in the TOTME apparatus. Starting from the MadX v6.5 nominal optic, a crystal is placed at different longitudinal and transversal positions: for each scheme a gaussian beam of protons with different kinematic variables is created and tracked along the optical line with crystal. The number of protons with transversal coordinates greater than 10σ+0.5mm, that is inside the Roman Pot, is compared with the total number of protons. The possible gain in acceptance is around 15-20%.  
TUPD032 RFQ Vacuum Brazing at CERN 1494
 
  • S. J. Mathot
    CERN, Geneva
  
  The aim of this paper is to describe the vacuum brazing procedure used at CERN for the brazing of Radio Frequency Quadrupole (RFQ). The RFQ is made of high precision machined OFE copper pieces assembled together. Vacuum brazing is one of the most promising techniques used to join the individual components leading to vacuum tightness and high precision alignment. The RFQ's brazed at CERN are made of four 100 or 120 cm long vanes (two majors and two minor vanes). Our brazing procedure consists of two steps. The first step involves the brazing of the four vanes in a horizontal position. The second step consists of brazing the vacuum stainless steel flanges to the copper structure in a vertical position. The paper describes the problems encountered with the alignment and the vacuum tightness. The difficulties related to the stress relaxation of the machined copper pieces during the brazing heat treatment are discussed. In addition, the solutions developed to improve the alignment of the brazed RFQ's are also presented.  
TUPD033 Fabrication of Crystals for Channelling of Particles in Accelerators 1497
 
  • A. Mazzolari, S. Baricordi, V. Guidi, G. Martinelli, D. Vincenzi
    UNIFE, Ferrara
  
  Channelling in bent crystals is used for beam extraction, focusing, collimation in accelerators machines, studies related to emission of coherent electromagnetic radiation and other topics. Distinctive features of performance increase is the availability of new techniques to manufacture the crystals within which channeling takes place. We propose a method to fabricate crystals through micromachining techniques, i.e., photolithography and anisotropic chemical etching. Patterning of a Si wafer with silicon nitride allows selective erosion of uncovered areas along specific atomic planes, resulting in a technique to dice Si wafers to the needed dimensions solely through chemical methods. Thus, it results in no damage to the crystal quality due to the dicing process. As was demonstrated by electron microscopy investigation, the crystal exhibits ultra flat lateral surfaces and simultaneously no amorphous layer at the entry face of the crystal with respect to the beam. The crystals were positively tested at the external line H8 of the SPS with 400 GeV protons for investigation on axial channeling and on single and multiple volume reflection experiments by the H8-RD22 collaboration.  
TUPD034 Review of the Mechanical Engineering Challenges Associated with the SNS Power Ramp Up 1500
 
  • G. R. Murdoch, D. W. Crisp, M. Holding, P. Ladd, K. G. Potter, R. T. Roseberry
    ORNL, Oak Ridge, Tennessee
  
  Since commissioning of the SNS in April 2006 the beam power has been steadily increasing towards the design intensity of 1.4 MW. Several areas of the accelerator have been shown to require modifications, upgrades or new designs of mechanical equipment to support the power ramp schedule. This paper presents mechanical engineering design work implemented since initial commissioning along with a review of current projects and discussion of mechanical engineering issues being addressed that are a direct result of design decisions made early in the project.  
TUPD035 Modeling of the RF-shield Sliding Contact Fingers for the LHC Cryogenic Beam Vacuum Interconnects Using Implicit and Explicit Finite Element Formulations 1503
 
  • D. Ramos
    CERN, Geneva
  
  The short interconnect length between the LHC superconducting magnets required the development of an optimised RF shielded bellows module, with a low impedance combined with compensation for large thermal displacements and alignment lateral offsets. Each bellows is shielded by slender copper-beryllium fingers working as pre-loaded beams in order to provide a constant force at the sliding contact. Unless the sliding friction and some geometrical parameters of the fingers are kept within a limited range, a large irreversible lateral deflection towards the vacuum chamber axis may occur and eventually block the beam aperture. The finite element analysis presented here simulates this failure mechanism providing a complete understanding of the finger behavior as well as the influence of the various design parameters. An implicit non-linear two-dimensional model integrating friction on the sliding contacts, geometrical non-linearity and plasticity was implemented in a first stage. The design was then verified through the whole working range using an explicit formulation, which overcame the instabilities resulting from the sudden release of internal energy stored in the finger.  
TUPD036 G4Beamline Simulations for Detector Development 1506
 
  • T. J. Roberts, K. B. Beard
    Muons, Inc, Batavia
  
  In current research programs to develop radiation detection instruments, simplifying assumptions are frequently made in estimating the resolutions and efficiencies attainable by neutron and gamma-ray instruments. Monte Carlo programs (such as Geant4) are capable of realistically modeling such problems, but the technical details of setting up, running, and interpreting the required simulations are beyond the ability of all but the most expert researchers. G4beamline, a program that is an interface to the Geant4 toolkit for the simulation of accelerator beam lines, is being extended to model detectors and related systems needed for applications related to nuclear nonproliferation and other users. The program is flexible, extremely user friendly, and requires no programming by users. Simulations of simple or complex detectors can be setup quickly and are accurately simulated using the power and accuracy of Geant4 for the transport of particles, including scattering, attenuation, interactions, and decays.  
TUPD037 Design and Development of Intercepting Devices at the Spallation Neutron Source 1508
 
  • R. T. Roseberry, S. Assadi, D. W. Crisp, K. R. Gawne
    ORNL, Oak Ridge, Tennessee
  
  Beam measurements in the LINAC and transport lines of the Spallation Neutron Source at Oak Ridge National Laboratory utilize a variety of intercepting instruments such as in-line emittance systems, wire scanners, scrapers and scintillation view screens. All of these devices require linear actuators with vacuum feedthroughs. The majority of the actuators acquired during the construction phase of the SNS were of commercial origin and have proven unable to meet long-term physics and engineering requirements. The predominant difficulties with these devices were lack of precision, reliability and longevity. Three new families of linear actuators have been developed at the SNS to address these deficiencies. The approach used in their development, has been to utilize a combination of commercially available linear motion components in custom built chassis to address the needs of a given set of applications. This approach has yielded devices that have met or exceeded expectations for accuracy, precision, radiation resistance, longevity and economy. Aspects of the underlying design of these actuators and their implementation will be presented at this conference.  
TUPD038 Beam Test of a Movable Collimator (Mask) with Low Beam Impedance 1511
 
  • Y. Suetsugu, K. Shibata
    KEK, Ibaraki
  • A. Morishige, Y. Suzuki, M. Tsuchiya
    Kinzoku Giken Co. Ltd., Ebina
  
  A movable collimator with low beam impedance for future high-intensity machines has been investigated in KEK*. The metal head of the collimator is supported by a dielectric material in order to reduce the interference with beams. The first test model was installed into the KEK B-factory (KEKB) positron ring last year. The head and the support was alumina ceramic, but only the head was coated by copper to realize a conductive layer. The support, however, was finally melted during the beam operation due to the overheating by intense electromagnetic fields induced by bunches. Based on the experience, the design was revised and the second test model was manufactured, where the head and the support were made of graphite and artificial diamond, respectively. Graphite is a conductive material with high thermal strength, and diamond, on the other hand, is a dielectric material with high thermal conductivity as well as the strength. The second test model is installed in the spring of this year, and tested again with beams during the beam operation to prove the principle. The results of the beam tests will be presented here.

* Y. Suetsugu, K. Shibata, A. Morishige, Y. Suzuki, M. Tsuchiya, “Design Study of a Movable Mask with Low Bema Impedance”, PRST-AB, 9, 2006, 103501.

 
TUPD039 Load Curves Distortion Induced by Fringe Field Effects in the Ion Nanoprobe 1514
 
  • Yu. V. Tereshonkov, S. N. Andrianov
    St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg
  
  Nanoprobes are known to be high precision systems, which require preliminary modeling for thorough analysis of optimal working modes. One of most crucial characteristics of the special class of such beam lines is the so-called load curves (or surfaces). This paper investigates one of the types of intrinsic effects, i.e. fringe fields and their influence on load curves and surfaces, which make it possible to construct the purposeful search of optimal working regimes for nanoprobes. A number of different models for fringe field presentation are discussed in the paper. Analytical and numerical methods and tools are used for analysis and selection of optimal parameters for fringe field models.  
TUPD040 Design, Manufacturing and Tests of a Micrometer Precision Mover for CTF3 Quadrupoles 1517
 
  • F. Toral, C. Burgos, D. Carrillo, L. García-Tabarés, J. L. Gutierrez, I. Rodriguez, E. Rodríguez García, S. Sanz, C. Vazquez
    CIEMAT, Madrid
  • E. Adli, N. C. Chritin, S. Doebert, J. A. Rodriguez
    CERN, Geneva
  • J. Calero
    CEDEX, Madrid
  
  A new remotely controlled moving table has been designed for the quadrupoles of the CTF3 Test Beam Line, as part of the beam based alignment system. This device must provide both vertical and horizontal (transverse to the beam) movements. The specifications request a reproducibility of ± 5 micron, with a resolution of 1 micron and a stroke of ± 4 mm. Due to the weight of the magnet, about 50 kg, and the space restrictions, a solution based on small stepping motors with integrated linear spindles has been chosen. The motor responsible of the vertical movement rests on a wedge, with a double purpose: to make the design more compact, and to increase the lifting force for a given motor size. Mechanical switches are used as end-of-movement sensors and home position detectors. The performed tests to check the mover prototype performance are also reported in this paper. Next step will be to launch series production, which will consist of 16 units.  
TUPD041 The Design of a 5 MeV Accelerator Based on Multipactor Electron Gun 1520
 
  • M. Zhong, C.-X. Tang, S. Zheng
    TUB, Beijing
  
  The Multipactor Electron Gun (MPG) based on the multipactor effect can produce short duration, high current and self-bunching electron beams. This paper presents our work on the design of an S-band accelerator based on MPG and the result of preliminary experiment. The mechanical structure was designed with ability of replacing secondary electron emitters. Pd-Ba alloy and Pt were used as the secondary electron emitters of the MPG. The distance between electrodes and the resonant frequency of the MPG can be adjusted separately by step motors. The parameter of the accelerator tube was optimized using numerical simulation with the design outlet energy of the electron is 5MeV and an average current of 100mA.  
TUPP046 Tunable Ferroelectric Based Technologies for Accelerator Components 1646
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • S. Kazakov
    KEK, Ibaraki
  • E. Nenasheva
    Ceramics Ltd., St. Petersburg
  • A. Tagantsev
    EPFL, Lausanne
  • V. P. Yakovlev
    Fermilab, Batavia, Illinois
  
  Low loss ferroelectric materials can be used as key elements in RF tuning and phase shifting components to provide fast, electronic control. These devices are under development for different accelerator applications in X, Ka and L - frequency bands. The exact design of these devices depends on the electrical parameters of the particular ferroelectric material to be used- its dielectric constant, loss tangent and tunability. BST based ferroelectric-oxide compounds have been found to be suitable materials for a fast electrically-controlled tuner for BNL and for high-power fast RF phase shifters to be used for SNS vector modulation applications. We present recent results on the development of BST based ferroelectric compositions synthesized for use in high power technology components. The BST(M) ferroelectrics have been tested using a transverse dc bias field. The tunability factor vs. dc field magnitude has been evaluated and the feasibility of transverse bias tuning for ferroelectric based accelerator components has been demonstrated.