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background

  
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MOPLT045 Vacuum Induced Backgrounds in the New HERA Interaction Regions proton, vacuum, interaction-region, radiation 647
 
  • M. Seidel, M.G. Hoffmann
    DESY, Hamburg
  After the rebuild of the HERA interaction regions the experimental detectors were limited by beam induced backgrounds. Four types of background mechanisms were observed and identified - proton gas scattering, lepton gas scattering, synchrotron radiation and proton beam-halo losses. With some refined beam steering methods it was possible to tune the synchrotron radiation background to acceptable limits. The remaining most important effect was the scattering of the beam particles, mostly the protons, at the residual gas. In this contribution we describe our systematic attempts to investigate the complex behavior of the beam gas background and the measures taken to improve the situation. This includes dynamic pressure profile simulations and measurements, experimental determination of the background sensitivity profile along the beamline, the pressure development with current and time, and residual gas analysis. The background conditions were finally improved due to long term conditioning with beam, modifications of internal masks which were heated by higher order mode losses and moderate improvements of the pumping speed at strategic locations.  
 
MOPLT051 Experimental Characterization of PEP-II Luminosity and Beam-beam Performance luminosity, simulation, beam-losses, betatron 665
 
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • M.A. Baak
    NIKHEF, Amsterdam
  • J. Seeman, M.K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
  The beam-beam performance of the PEP-II B-Factory has been studied by simultaneously measuring the instantaneous luminosity, the horizontal and vertical e+ and e- beam sizes in the two rings, and the spatial extent of the luminous region as extracted from BaBar dilepton data. These quantities, as well as ring tunes, beam lifetimes and other collider parameters are recorded regularly as a function of the two beam currents, both parasitically during routine physics running and in a few dedicated accelerator physics experiments. They are used to quantify, project, and ultimately improve the PEP-II performance in terms of achieved beam-beam parameters, dynamic-beta enhancement, and current-dependence of the specific luminosity.  
 
MOPLT096 Machine Induced Background in the High Luminosity Experimental Insertion of the LHC Project hadron, insertion, simulation, shielding 755
 
  • V. Talanov, I. Azhgirey, I. Baishev
    IHEP Protvino, Protvino, Moscow Region
  • K.M. Potter
    CERN, Geneva
  The methodical approach, developed for the solution of the radiation problems in the LHC project, is used for the estimation of the machine induced background in the high luminosity experimental insertion IR1. The results of the cascade simulations are presented for the cases of the proton losses in the cold and warm parts of the collider. The formation of the machine induced background in the interaction region is discussed.  
 
MOPLT103 Radiation Resistant Magnetic Sensors for Accelerators radiation, permanent-magnet, monitoring, electron 773
 
  • I. Bolshakova, R. Holyaka
    LPNU, Lviv
  • S. Kulikov
    JINR, Dubna, Moscow Region
  • M. Kumada
    NIRS, Chiba-shi
  • C. Leroy
    Université de Montréal, Groupe de la Physique des Particules, Montréal, Québec
  The technology of obtaining the radiation resistant magnetic sensors, which characteristics remain stable under the irradiation with high dose of fast neutrons was designed. Radiation resistant sensors are developed on the base of InSb. While irradiation with neutron flux of 1010 n*cm-2*c-1 with energies 0.1…13?MeV, with the thermal neutrons part in the general flux of 20% and intermediate fluxes of 25%, the main sensors’ characteristics, that is their sensitivity to the magnetic field, change no more than for 0.05% up to the fluence of 1*1015 n*cm-2 and no more than for 1% up to the fluence of 3*1016 n*cm-2. Radiation resistant sensors are used for development of magnetic field monitoring system with measuring channels accuracy of 0,01%, which have a function of temperature measurement with the accuracy of 0.1?С at the place of sensor location, moreover, it has self diagnostics and self correction functions. This system passed the long-term testing of continuous 3 months operation at the Neutron Physics Laboratory, JINR, Dubna at the IBR-2 neutron reactor.  
 
MOPLT106 MICE: the Muon Ionisation Cooling Experiment emittance, factory, scattering, instrumentation 782
 
  • M. Ellis
    Imperial College of Science and Technology, Department of Physics, London
  The provision of intense stored muon beams would allow the properties of neutrinos to be measured precisely and provide a route to multi-TeV lepton-anti-lepton collisions. The short muon-lifetime makes it impossible to employ traditional cooling techniques while maintaining the muon-beam intensity. Ionisation cooling, a process in which the muon beam is passed through a series of liquid hydrogen absorbers followed by accelerating RF-cavities, is the proposed cooling technique. The international Muon Ionisation Cooling Experiment (MICE) collaboration proposes to perform an engineering demonstration of ionisation cooling. The MICE cooling channel, the instrumentation and the implementation at the Rutherford Appleton Laboratory is described together with the predicted performance of the channel and the measurements that will be made.  
 
MOPLT114 Modeling of Beam Loss in Tevatron and Backgrounds in the BTeV Detector beam-losses, hadron, collimation, shielding 803
 
  • A. Drozhdin, N. Mokhov
    Fermilab, Batavia, Illinois
  Detailed STRUCT simulations are performed of beam loss rates in the vicinity of the BTeV detector in the Tevatron C0 interaction region due to beam-gas nuclear elastic interactions, outscattering from the collimator jaws and an accidental abort kicker prefire. Corresponding showers induced in the machine components and background rates on the BTeV Detector are modeled with the MARS14 code. It is shown that a steel mask located in front of the last four dipoles upstream the C0 can reduce the accelerator-related background rates in the detector by an order of magnitude.  
 
MOPLT127 Diagnosing the PEP-II Injection System injection, kicker, septum, luminosity 833
 
  • F.-J. Decker, M.H. Donald, R.H. Iverson, A. Kulikov, G.C. Pappas, M. Weaver
    SLAC, Menlo Park, California
  The injection of beam into the PEP-II B-Factory, especially into the High Energy Ring (HER) has some challenges. A high background level in the BaBar Detector has so far inhibited us from trickling charge into the HER similar to the Low Energy Ring (LER). Analyzing the injection system has revealed many issues which could be improved. The injection bump between two kickers was not closed, mainly because the phase advance wasn't exactly 180 degrees and the two kicker strengths were not balanced. Additionally we found reflections which kick the stored beam after the main kick and cause the average luminosity to drop about 3% for a 10 Hz injection rate. The strength of the overall kick is nearly twice as high than the design, indicating a much bigger effective septum thickness. Compared with single beam the background is worse when the HER beam is colliding with the LER beam. This hints that the beam-beam force and the observed vertical blow-up in the HER pushes the beam and especially the injected beam further out to the edge of the dynamic aperture or beyond.  
 
MOPLT146 Trickle-charge: a New Operational Mode for PEP-II injection, luminosity, diagnostics, feedback 881
 
  • J.L. Turner, S. Colocho, F.-J. Decker, S. Ecklund, A.S. Fisher, R.H. Iverson, C. O'Grady, J. Seeman, M.K. Sullivan, M. Weaver, U. Wienands
    SLAC, Menlo Park, California
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  In regular top-up-and-coast operation, PEP-II average luminosity is about 70…75% of the peak luminosity due to detector ramp-down and ramp-up times plus the time it takes to top-up both beams. We recently commissioned a new operational mode where the Low Energy Ring is injected continuously without ramping down the detector. The benefits?increased luminosity lifetime and roughly half the number of top-ups per shift?were expected to give an increase in delivered luminosity of about 15% at the same peak luminosity; this was confirmed in test runs. In routine trickle operation, however, it appears that the increase in delivered luminosity is more than twice that due to an increase in availability credited to the more stable operating conditions during trickle operation. In this paper we will present our operational experience as well as some of the diagnostics we use to monitor and maintain tuning of the machine in order to control injection background and protect the detector. Test runs are planned to extend trickle-charge operation to the High Energy Ring as well.  
 
MOPLT162 Continuous Abort Gap Cleaning at RHIC ion, accumulation, beam-losses, heavy-ion 908
 
  • K.A. Drees, R.P. Fliller III, W. Fu, R. Michnoff
    BNL, Upton, Long Island, New York
  Since the RHIC Au-Au run in the year 2001 the 200 MHz cavity system was used at storage and a 28 MHz system during injection and acceleration.The rebucketing procedure potentially causes a higher debunching rate of heavy ion beams in addition to amplifying debunching due to other mechanisms. At the end of a four hour store, debunched beam can easily account for more than 30% of the total beam intensity. This effect is even stronger with the achieved high intensities of the RHIC run 2004. A beam abort at the presence of a lot of debunched beam bears the risk of magnet quenching and experimental detector damage due to uncontrolled beam losses. Thus it is desirable to avoid any accumulation of debunched beam from the beginning of each store, in particular to anticipate cases of unscheduled beam aborts due to a system failure. A combination of a fast transverse kicker and the new 2-stage copper collimator system is used to clean the abort gap continuously throughout the store with a repetition rate of 1 Hz. This report gives an overview of the new gap cleaning procedure and the achieved performance.  
 
MOPLT163 Luminosity Optimization Using Automated IR Steering at RHIC luminosity, feedback, coupling, electron 911
 
  • K.A. Drees, T. D'Ottavio
    BNL, Upton, Long Island, New York
  The goal of the RHIC 2004 Au-Au run was to maximize the achieved integrated luminosity. One way is to increase beam currents and minimize beam transverse emittances. Another important ingredient is the minimization of time spent on activities postponing the declaration of 'physics conditions', i.e. stable beam conditions allowing the experimental detectors to take data. Since collision rates are particularly high in the beginning of the store the integrated luminosity benefits considerably from any minute saved early in the store. In the RHIC run 2004 a new IR steering application uses luminosity monitor signals as a feedback for a fully automated steering procedure. This report gives an overview of the used procedure and summarizes the achieved results.  
 
MOPLT164 Bunch Patterns and Pressure Rise in RHIC electron, simulation, vacuum, injection 914
 
  • W. Fischer, U. Iriso
    BNL, Upton, Long Island, New York
  The RHIC luminosity is limited by pressure rises with high intensity beams. At injection, the dominating cause for the pressure rise was shown to be electron clouds. We discuss the distributions of bunches along the circumference that minimize the electron cloud effect in RHIC. Experimental data are compared with simulation results, and experiences at the B-factories.  
 
MOPLT165 Luminosity Increases in Gold-gold Operation in RHIC luminosity, vacuum, power-supply, electron 917
 
  • W. Fischer, L. Ahrens, J. Alessi, M. Bai, D. Barton, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, D. Bruno, J. Butler, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, W. Fu, G. Ganetis, J. Glenn, T. Hayes, P. He, H.-C. Hseuh, H. Huang, P. Ingrassia, U. Iriso, R. Lee, Y. Luo, W.W. MacKay, G. Marr, A. Marusic, R. Michnoff, C. Montag, J. Morris, T. Nicoletti, B. Oerter, C. Pearson, S. Peggs, A. Pendzick, F.C. Pilat, V. Ptitsyn, T. Roser, J. Sandberg, T. Satogata, C. Schultheiss, A. Sidi-Yekhlef, L. Smart, S. Tepikian, R. Tomas, D. Trbojevic, N. Tsoupas, J. Tuozzolo, J. Van Zeijts, K. Vetter, K. Yip, A. Zaltsman, S.Y. Zhang, W. Zhang
    BNL, Upton, Long Island, New York
  After an exploratory phase, during which a number of beam parameters were varied, the RHIC experiments now demand high luminosity to study heavy ion collisions in detail. Presently RHIC operates routinely above its design luminosity. In the first 4 weeks of its current operating period (Run-4) the machine has delivered more integrated luminosity that during the 14 weeks of the last gold-gold operating period (Run-2). We give an overview of the changes that increased the instantaneous luminosity and luminosity lifetime, raised the reliability, and improved the operational efficiency.  
 
MOPLT178 RHIC Pressure Rise ion, electron, beam-losses, luminosity 944
 
  • S.Y. Zhang, J. Alessi, M. Bai, M. Blaskiewicz, P. Cameron, K.A. Drees, W. Fischer, R.P. Fliller III, D. Gassner, J. Gullotta, P. He, H.-C. Hseuh, H. Huang, U. Iriso, R. Lee, Y. Luo, W.W. MacKay, C. Montag, B. Oerter, S. Peggs, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, L. Smart, P. Thieberger, D. Trbojevic, J. Van Zeijts, L. Wang, J. Wei, K. Zeno
    BNL, Upton, Long Island, New York
  Beam induced pressure rise remains an intensity limit at the RHIC for both heavy ion and polarized proton operations. The beam injection pressure rise at warm sections has been diagnosed due to electron cloud effect. In addition, pressure rise of heavy ion operation at the beam transition has caused experiment background problem in deuteron-gold run, and it is expected to take place in gold-gold run at high intensities. This type of pressure rise is related to beam momentum spread, and the electron cloud seems not dominant. Extensive approaches for both diagnosis and looking-for-remedies are undergoing in the current gold operation, RUN 4. Results of beam scrubbing, NEG pipe in RHIC ring, beam scraping test of ion desorption, beam momentum effect at the transition, beam gap effect, solenoid effect, and NEG pipe ion desorption test stand will be presented.  
 
TUPKF075 Inductive Output Tubes for Particle Accelerators gun, electron, microtron, feedback 1111
 
  • H.P. Bohlen
    CPI, Palo Alto, California
  • E. Davies, P. Krzeminski, Y. Li, R.N. Tornoe
    CPI/EIMAC, San Carlos, California
  The Inductive Output Tube (IOT) is not widely used as an RF power source in particle accelerators yet, but this is about to change rapidly. One reason for this change is the IOT's "coming of age": almost twenty years of successful operation in television transmitters have lead to high refinement of IOT technology and proven reliability. The other reason is the fitness of the IOT to especially meet accelerator requirements: high efficiency, no need for power back-off to achieve fast feed-back regulation, and the possibility to pulse the RF without using a high-voltage modulator. Two classes of IOTs are available so far for application in particle accelerators. One of them consists of UHF external-cavity devices, frequency-tunable and producing output power levels up to 80 kW CW. The second class has been developed only recently. These are L-band IOTs with internal output cavities for 1.3 and 1.5 GHz, respectively, featuring output power levels between 15 and 30 kW CW. Extensive computer simulations have lead to the conclusion that even higher-power IOTs, such as a 300 kW peak-power, long-pulse L-band tube, are feasible.  
 
WEPKF056 Reducing Output Current Ripple of Power Supply with Component Replacement power-supply, instrumentation, feedback, synchrotron 1732
 
  • K.-B. Liu, C.-S. Fann
    NSRRC, Hsinchu
  Correction magnets of synchrotron storage ring are served with linear power supplies (correction power supply) with 100 ppm output current ripple in National Synchrotron Radiation Research Center. Reducing output current ripple of correction power supply might reduce perturbation of beam position of storage ring. Replace correction power supplies with lower output current ripple ones is straightforward but costs lots of money. Without adding any other circuit and electronic component, some components of correction power supply are replaced by ones with more precious and lower output fluctuation; so that the same circuitry structure of correction power supply is kept without increasing its complexity and could reach 25 ppm output current ripple.  
 
WEPLT016 Logistics of LHC Cryodipoles: from Simulation to Storage Management simulation, insertion, vacuum, quadrupole 1855
 
  • K. Foraz, B. Nicquevert, D. Tommasini
    CERN, Geneva
  The particles traveling in the Large Hadron Collider are guided by superconducting magnets. The main magnets (cryodipoles) are 16 m long, 30 tons objects placed with accuracies of few tenths of mm and therefore imposing challenging requirements for handling and transportation. Numerous contracts are constraining the production and installation of these cryodipoles. These contracts have been rated according to the baseline schedule, based on a "just in time" scheme. However the complexity of the construction and the time required to fully test the cryodipoles before installation in the LHC required to decouple as much as possible each contract from the others' evolutions and imposed temporary storage between different assembly and test steps. Therefore a tool simulating the logistics was created in order to determine the number of cryodipoles to store at the various stages of their production. In this paper the organization of cryodipole flow and the main challenges of logistics are analyzed on the basis of the planning of each main step before installation. Finally the solutions implemented for storage, handling and transportation are presented and discussed.  
 
WEPLT128 Charge Particle Source for Industrial and Research Accelerators Operating at the Poor Vacuum Conditions vacuum, electron, cathode, ion 2149
 
  • E.O. Popov, A.A. Pashkevich, S.O. Popov, A.V. Vitugov
    IOFFE, St. Petersburg
  We investigated the original method of fabrication of the great number of emitting tips by pulling liquid metal through the holes in track membrane under influence of electric field. The track membranes are produced by cyclotron of Physicotechnical Institute. This method enables to fabricate up to 1·108 emitting tips per square cm. Special test facility to investigate emitter parameters operating at different values of background residual gas pressure was designed and developed. The liquid metal multiple tip field emitters possess some unique characteristics which are attractive in accelerators for material irradiation: unlimited life expectancy, large current densities (about 100 mA per sq. cm), practically unlimited surface, stable emission in poor vacuum.  
 
THPKF036 Developments of the FZP Beam Profile Monitor damping, alignment, coupling, radiation 2353
 
  • N. Nakamura, M. Fujisawa, H. Kudo, H. Sakai, K. Shinoe, H. Takaki, T. Tanaka
    ISSP/SRL, Chiba
  • H. Hayano, T. Muto
    KEK, Ibaraki
  A beam profile monitor based on two Fresnel Zone Plates (FZPs) has been developed at the KEK-ATF damping ring. This monitor can perform real-time imaging of the electron beam with an X-ray imaging optics and the synchrotron radiation and measure the horizontal and vertical beam sizes with a high spatial resolution. A clear electron-beam image with the vertical beam size less than 10 microns was already obtained in the early measurements [*]. Thereafter some of the optical elements, the crystal monochromator, X-ray CCD camera and FZP holders, were improved and an X-ray pinhole mask was installed between the two FZPs for reducing the background of X-rays passing through the MZP (the second FZP). Aberrations due to alignment errors of the FZPs were studied with an analytical approach and a ray-tracing method and vibrations of the optical elements were measured in order to estimate their effects on the system performance. In this paper, we will present developments of the beam profile monitor with results of some beam-size measurements.

* K. Iida et al., Nucl. Instrum. Methods A506, p.41-49 (2003); N. Nakamura et al., Proc. of PAC2003, p.530-532

 
 
THPLT026 Beam Profile Measurements at PETRA with the Laserwire Compton Scattering Monitor laser, photon, positron, collider 2529
 
  • T.  Kamps
    BESSY GmbH, Berlin
  • K. Balewski, H.-C. Lewin, S. Schreiber, K. Wittenburg
    DESY, Hamburg
  • G.A. Blair, G. Boorman, J. Carter, F. Poirier
    Royal Holloway, University of London, Surrey
  • S.T. Boogert
    UCL, London
  • T. Lefevre
    CERN, Geneva
  The vertical beam profile at the PETRA positron storage ring has been measured using a laserwire scanner. A laserwire monitor is a device which can measure high brilliant beam profiles by scanning a finely focused laser beam non-invasively across the charged particle beam. Evaluation of the Compton scattered photon flux as a function of the laser beam position yields the transverse beam profile. The aim of the experiment at PETRA is to obtain the profile of the positron beam at several GeV energy and several nC bunch charge. Key elements of laserwire systems are currently being studied and are described in this paper such as laser beam optics, a fast scanning system and a photon calorimeter. Results are presented from positron beam profile scans using orbit bumps and a fast scanning scheme.  
 
THPLT028 High Precision Cavity Beam Position Monitor dipole, resonance, coupling, damping 2535
 
  • A. Liapine, H. Henke
    TET, Berlin
  A cavity beam position monitor is proposed for measuring the beam deflection in the TESLA energy spectrometer. The precision of the measurement has to be better than 1 micrometer. A slotted cavity is chosen as pick-up in order to reject the background signals and enhance the precision and the dynamic range of the monitor. The paper gives the design overview for two prototypes with operating frequencies of 1.5 GHz and 5.5 GHz, respectively. The results obtained on the test bench with direct conversion electronics are presented. A resolution of about 100 nm was achieved.  
 
THPLT030 A Novel Device for Non-intersecting Bunch Shape Measurement at the High Current GSI-Linac electron, linac, space-charge, ion 2541
 
  • P. Forck, C. Dorn, M.H. Herty, P. Strehl
    GSI, Darmstadt
  • V. Peplov
    RAS/INR, Moscow
  • S. Sharamentov
    ANL, Argonne, Illinois
  Due to the high current of heavy ions accelerated at the UNILAC at GSI, non-intersecting beam diagnostics are mandatory. For bunch length and bunch structure determination in the range of 0.3 to 5 ns a novel device has been realized. It uses the time spectrum of secondary electrons created by atomic collisions between beam ions and residual gas molecules. These electrons are accelerated by an electric field of 400 V/mm toward an electro-static energy analyzer. The analyzer is used to restrict of the effective source region. Then the electrons are deflected by an rf-resonator running in phase with the acceleration frequency (36 or 108 MHz) to transform the time spectrum into spatial separation. The detection is done with a multi-channel plate equipped with a phosphor screen and observed by a digital CCD camera. The achieved time resolution is at least 50 ps, corresponding to 2 degree of rf frequency. The general layout of the device and first results will be presented.  
 
THPLT045 A more Accurate Approach to Calculating Proton Bunch Evolution under Influence of Intra-beam Scattering in a Storage Ring. scattering, proton, synchrotron, storage-ring 2583
 
  • I.V. Agapov, F.J. Willeke
    DESY, Hamburg
  Some perturbations of discrete nature are known to influence the performance of a proton storage ring, contributing to parasitic background, decay of beam currents and bunch tail buildup. Such are, for example, intra-beam scattering and residual gas scattering .These processes are to a big extent described by existing analytical theory. The latter, employing a large amount of averaging, usually neglects effects arising from system nonlinearity. So, the motion of tail particles in the presence of a sufficiently nonlinear RF voltage under influence of intra-beam scattering strongly deviates from the average across the bunch and the analytical approach seems inadequate for it. To overcome this situation we have developed more accurate numerical methods for calculations of bunch evolution under influence of a rather broad class of jump-like perturbations. Here we present the computational algorithms and their application to assessment of coasting beam and proton background in HERA-p.  
 
THPLT052 Measurement of Relative Gas Chamber Pressure in Narrow Straight Section Vacuum Vessels by Observing Gas Bremstrahlung radiation, vacuum, electron, beam-losses 2601
 
  • G.A. Naylor, B. Joly, D. Robinson
    ESRF, Grenoble
  The measurement of gas pressure inside long, small cross section, vacuum vessels is difficult due to the distance between the centre of the vacuum vessel and vacuum gauges (leading to a low vacuum conductance). Following initial chamber installation, significant out-gassing is observed leading to a significant pressure bump within the chamber. A modified beam loss detector has been developed in order to monitor the gamma radiation produced by the collision of the 6GeV electrons in the storage ring with residual gas atoms. The narrow beam of gamma radiation is intercepted at various points by high Z materials in the beam line front-end allowing a radiation shower to be detected outside the vacuum vessel proportional to the gas pressure in the corresponding storage ring straight section. Various locations are considerred and results shown.  
 
THPLT060 An Automatic Beam Characterization Instrument for Proton Therapy Applications proton, radiation, monitoring, diagnostics 2625
 
  • D. Giove, C. De Martinis, M. Mauri
    INFN/LASA, Segrate (MI)
  • C. Cirrone, G. Cuttone
    INFN/LNS, Catania
  The characterization in the transverse plane of the beam is a fundamental step in the design of a proton therapy facility. In this paper we will describe an automatic system able to measure the transverse profiles of the proton beam used in the Catana facility at LNS-Catania. The system has been designed as an autonomous equipment able to acquire optical images of the beam (after an interaction with a converter) and to elaborate them to extract the relevant parameters. The equipment may be interfaced to the rest of the control system of the facility and to the operator interface to provide high level control and monitoring tools. Operational experience will be discussed and the results so far obtained will be outlined.  
 
THPLT070 Design and Constriction of Coronagraph for Observation of Beam Halo factory, photon, optics, scattering 2655
 
  • T. Mitsuhashi
    KEK, Ibaraki
  The coronagraph is a spatial telescope to observe the sun-corona by artificial eclipse. The concept of this apparatus is to realize the Schlieren-optical system for cutting the bright diffraction fringes in order to observe a less-bright object surrounding the main image such as the sun-corona. We applied this concept for the observation of the surrounding structure (halo, tail) of the beam. Since the background is mainly scattered light come from the objective lens, the key point to observe a less-intense object is to reduce scattering light from objective lens. We used a very well-polished lens (better than scratch and dig 20/20) as objective lens, and succeeded to obtain the signal to background ratio better than 10-5. As a test, we tried to observe the tail of beam by hiding the central peak with artificial eclipse by the coronagraph at Photon Factory storage ring. We succeeded to observe the tail of beam which has an intensity range of 1/104 of the peak intensity.  
 
THPLT106 Measurement of Beam Polarization in VEPP-3 Storage Ring using Internal Target-based Moeller Polarimeter polarization, target, electron, scattering 2730
 
  • A.V. Grigoriev, V. Kiselev, E.V. Kremyanskaya, E. Levichev, S.I. Mishnev, S.A. Nikitin, D.M. Nikolenko, I.A. Rachek, Y.V. Shestakov, D.K. Toporkov, V.N. Zhilich
    BINP SB RAS, Novosibirsk
  A method for beam polarization measurement in a storage ring has been for the first time developed and applied based on measuring the asymmetry in scattering of polarized beam electrons on the internal polarized gas jet target. Using this method we have studied the polarization in VEPP-3 booster storage ring. VEPP-3 is the source of polarized beams for VEPP-4M electron-positron collider in the planned experiment on high-precision mass measurement of tau-lepton near the production threshold of the latter (1777 MeV). Radiative polarization of beams obtained in VEPP-3 is used for absolute calibration of particle energy by the resonant depolarization technique after injection into VEPP-4M ring. The polarimeter design is described. Results of polarization measurements performed in 60 MeV range of VEPP-3 energy contiguous from above to tau-lepton production threshold are presented and discussed. The depolarizing influence of the integer machine spin resonance (1763 MeV) as well as of the combination spin resonances with the betatron frequencies are found to be significant.  
 
THPLT112 Methods and Instrumentation for Measurement of Low Ion Beam Currents at Cryring ion, pick-up, injection, monitoring 2748
 
  • A. Paal, A. Källberg, A. Simonsson
    MSL, Stockholm
  • J. Dietrich, I. Mohos
    FZJ/IKP, Jülich
  In many CRYRING experiments an accurate measurement of the circulating ion beam current is essential for determination of e.g. absolute cross sections. However, the current produced from the ion source can be very low. Furthermore, when surface barrier detectors are used, for example in the merged electron-ion beam experiments, the current has to be kept low to avoid saturation. With new electronics, using an Integrating Current Transformer with 5 V/A sensitivity, the current resolution of the Bergoz Beam Charge Monitor (BCM) has been increased to below 1 nA for bunched beams. The sum signal of the capacitive pick-up located at the farthest point from the RF-system is integrated by a second gated integrator. The RMS resolution is about 100 pA. To measure the intensity of coasting beams neutral particle detectors and a residual-gas beam profile monitor are used, calibrated with the BCM output during 20-100 ms after acceleration. The micro-channel plate detectors can handle a few Mcps count rate with a maximum 1 cps dark count rate. Presently a 50 Mcps secondary electron multiplier is being tested as a neutral particle monitor, having a maximum dark count rate of 0.05 cps  
 
THPLT114 A New Mono-energetic Neutron Beam Facility in the 20-180 MeV Range proton, target, ion, light-ion 2753
 
  • V.G. Ziemann, L.-O. Andersson, T. Bergmark, O. Bystrom, A. Bäcklund, H. Calen, L. Einarsson, C. Ekström, J. Fransson, K.J. Gajewski, N. Haag, T. Hartman, E. Hellbeck, T. Johansen, O. Jonsson, B. Lundström, R.P. Peterson, L. Pettersson, A. Prokofiev, D. Reistad, P.-U. Renberg, R. Wedberg, D. Wessman, L. Westerberg, D. van Rooyen
    TSL, Uppsala
  • J. Blomgren, S. Pomp, U. Tippawan, M. Österlund
    INF, Uppsala
  Recent interest in nuclear applications involving neutrons, like ransmutation of nuclear waste, fast-neutron cancer therapy, dose to personnel in aviation and electronics failures due to cosmic-ray neutrons, motivate the development of a facility producing intense mono-energetic neutron beams. At The Svedberg laboratory (TSL), Uppsala, Sweden, we have developed such a facility by utilizing the existing cyclotron and inserting a flexible Lithium target in a rebuilt beam line. The new facility can operate at unsurpassed quasi-monoenergetic neutron intensities and provides large flexibility of the neutron beam properties, like diameter and shape.  
 
THPLT168 XAL - The SNS Application Programming Infrastructure klystron, linac, quadrupole, monitoring 2855
 
  • J. Galambos, C. Chu, S.M. Cousineau, T. Pelaia, A. Shishlo
    ORNL/SNS, Oak Ridge, Tennessee
  • C. Allen, C. McChesney
    LANL/LANSCE, Los Alamos, New Mexico
  • W.-D. Klotz
    ESRF, Grenoble
  • I. Kriznar, A. Zupanc
    Cosylab, Ljubljana
  A Java programming infrastructure for high level applications has been developed and is being used for the Spallation Neutron Source (SNS). The framework provides a hierarchal view of the accelerator and hides much of the underlying control system details. The hierarchy is database configured, facilitating sharing of applications across different beamlines, shielding the programmer from detailed knowledge of signal names, and allowing wholesale updating of applications. An important aspect of the framework is an online model, which can be run for design values, live machine values or user selected tuning values. Sample applications will be shown.  
 
THPLT173 RHIC BPM Performance: Comparison of Run 2003 and 2004 proton, instrumentation, pick-up, quadrupole 2867
 
  • R. Calaga, R. Tomas
    BNL, Upton, Long Island, New York
  Identification of malfunctioning BPMs plays an important role in any orbit or turn-by-turn analysis. Singular value decomposition (SVD)and Fourier transform methods were recently employed to identify malfunctioning BPMs at RHIC. A detailed statistical comparison between the two methods for Run 2003 was in good agreement and proved to be a robust method to identify faulty BPMs. We evaluate detailed BPM performance for different versions of BPM low-level software in 2003 and 2004.  
 
FRXBCH02 Towards Higher Luminosities in B and Phi Factories luminosity, damping, emittance, electron 286
 
  • P. Raimondi
    INFN/LNF, Frascati (Roma)
  A brief review of the performances of the existing Factories will be presented. Such machines have been proved extremely successful, for both particle and accelerator physics. To further extend their physics reach, several plans are under way to upgrade the existing colliders, in order to increase their luminosity up to an order of magnitude. Will also be described several new schemes and ideas to realize full ?Second Generation Factories? aimed at luminosities two order of magnitude higher then what achieved so far.  
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