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beam-losses

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MOO3A01 Optical Transition Radiation Monitor for High Intensity Proton Beam at the J-PARC background, radiation, target, proton 30
 
  • A. Toyoda, A. Agari, E. Hirose, M. Ieiri, Y. Katoh, M. Minakawa, H. Noumi, Y. Sato, Y. Suzuki, H. Takahashi, M. Takasaki, K. H. Tanaka, H. Watanabe, Y. Yamanoi
    KEK, Tsukuba
  The OTR is a powerful tool to observe 2-dimensional information of beam profile at the high intensity beamline because the OTR intensity only depends on the screen reflectivity so that we can minimize a beam loss. However, it is necessary to overcome large background due to the Cerenkov radiation and low radiation tolerance of camera system. The purpose of the present effort is to achieve small background and good S/N and to prolong the lives of the camera system. This requires that amount of potential Cerenkov radiator be minimized and radiation level at the camera system be suppressed. For this requirement, we design and develop an OTR monitor with the optical system of a Newtonian telescope type. Detail design of the optical system and a result of background measurement performed at one of primary proton beam lines of our old 12 GeV Proton Synchrotron will be presented.  
 
TUO1A01 Bunched Beam Stochastic Cooling for RHIC kicker, proton, ion, pick-up 39
 
  • J. M. Brennan, M. Blaskiewicz, F. Severino
    BNL, Upton, Long Island, New York
  Stochastic cooling is an effective and well-established accelerator technology for improving beam quality. However, stochastic cooling of high frequency bunched beam has always proved problematic. We have built a stochastic cooling system for heavy ions in RHIC that is used on bunched beam. The purpose is to counteract Intra-Beam Scattering and improve integrated luminosity. The chief technical challenge of bunched beam is the strong coherent frequency components in the beam that contaminate the Schottky spectrum. Technical solutions for overcoming this problem are described. Results from commissioning in one ring of RHIC are reported.  
 
TUPB10 Proposed Beam Position and Phase Measurements for the LANSCE Linac linac, simulation, bunching, instrumentation 78
 
  • J. D. Gilpatrick, B. Blind, S. S. Kurennoy, R. C. McCrady, J. F. O'Hara, C. Pillai, J. F. Power, L. Rybarcyk
    LANL, Los Alamos, New Mexico
  There is presently an ongoing effort to develop beam position and phase measurements for the Los Alamos Neutron Science Center (LANSCE) linac associated with an improvement project known as the LANSCE Refurbishment. This non-interceptive measurement’s purpose is to provide both beam measurements of phase for determining rf-cavity phase and amplitude set points, and position measurements for determining the 805-MHz linac input transverse position and trajectories. The measurement components consist of a four-electrode beam position and phase monitor (BPPM), a cable plant that transports the 201.25-MHz signals, electronics capable of detecting phase and amplitude signals, and associated software that communicates with a mature LANSCE control system. This paper describes measurement requirements, proposed beam line device and some initial device bench measurements, initial designs of the associated electronics, and some of the difficulties developing these beam measurements in an operational facility.  
 
TUPB21 Experience with Libera Beam Position Monitors at DELTA kicker, diagnostics, storage-ring, pick-up 111
 
  • P. Hartmann, J. Fürsch, D. Schirmer, T. Weis, K. Wille
    DELTA, Dortmund
  Libera beam posiotion monitor electronics have been installed at the electron storage ring Delta in order to extend the capabilities of the BPM system to turn-by-turn orbit measurements. This report covers the integration of Liberas into the beam diagnostics infrastructure at DELTA and its control system EPICS. Prior to their application in user runs the devices have undergone characterization measurements in a BPM teststand and during machine runs for accelerator physics. Results of these measurements are compared to measurements with DELTAs standard BPM electronics. The necessary clock and trigger signals are provided by a low-cost signal distribution device developed at DELTA.  
 
TUPB25 Beam Profile Measurement with Optical Fiber Sensors at FLASH undulator, radiation, controls, monitoring 123
 
  • W. Goettmann, F. Wulf
    HMI, Berlin
  • M. Körfer
    DESY, Hamburg
  The measurement setup is based on wire scanners, optical fibers mounted symmetrically around the beam line over the full length (30 m) of the undulator section, a signal conditioning unit and a data acquisition system. The fiber sensors along the beam line allow the measurement of the spatial distribution of the scattered beam caused by the wire scanner. At each increment of the wire scanner, the generated Cherenkov light in the fiber sensors - which is proportional to the intensity of the scattered electron shower - is measured. As an improvement, the shower is not only measured at a singular location but over the entire length of the undulator section. Each integral of the generated Cherenkov light along the beam line gives one point of the transversal beam profile. Accomplishing an x-y-scan leads to a two dimensional profile of the beam. The synchronisation with the beam trigger allows the characterization of each bunch. The measured data are visualized in real time and stored in a log file for extended evaluation. The high sensitivity of the system allows an accurate monitoring of the beam profile as well as HALO measurement.  
 
WEPB04 The VEPP-4M Dynamic Aperture Determination Through the Precise Measurement of the Beam Lifetime dynamic-aperture, simulation, insertion, collider 238
 
  • A. N. Zhuravlev, S. I. Gluhov, V. F. Gurko, A. D. Khilchenko, V. A. Kiselev, A. N. Kvashnin, E. B. Levichev, O. I. Meshkov, P. A. Piminov, V. V. Smaluk, P. V. Zubarev
    BINP SB RAS, Novosibirsk
  To determine experimentally the particle stable area in the electron-positron collider VEPP-4M we measure the beam life time with high accuracy as a function of moving aperture. The measurement is performed by a photodiode installed in the collider diagnostic beam line. The experimental set up and the measurement results are described. Comparison with the tracking simulation is presented.  
 
WEPC03 Secondary Electron Emission Beam Loss Monitor for LHC electron, proton, simulation, radiation 313
 
  • D. K. Kramer, B. Dehning, G. Ferioli, E. B. Holzer
    CERN, Geneva
  Beam Loss Monitoring (BLM) system is a vital part of the active protection of the LHC accelerators’ elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modeled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production. The prototypes were calibrated by proton beams in CERN PS Booster dump line, SPS transfer line and in PSI Optis line. The results were compared to the simulations.  
 
WEPC06 Single gain radiation tolerant LHC beam loss acquisition card radiation, monitoring, survey, insertion 319
 
  • E. Effinger, B. Dehning, J. E. Emery, G. Ferioli, C. Zamantzas
    CERN, Geneva
  The beam loss monitoring system is one of the most critical elements for the protection of the LHC. It must prevent the super conducting magnets from quenches and the machine components from damages, caused by beam losses. Ionization chambers and secondary emission based detectors are used on several locations around the ring. The sensors are producing a signal current, which is related to the losses. This current will be measured by a tunnel card, which acquires, digitizes and transmits the data via an optical link to the surface electronic. The usage of the system, for protection and tuning of the LHC and the scale of the LHC, imposed exceptional specifications of the dynamic range and radiation tolerance. The input dynamic allows measurements between 10pA and 1mA and its protected to high pulse of 1.5kV and its corresponding current. To cover this range, a current to frequency converter in combination with an ADC is used. The integrator output voltage is measured with an ADC to improve the resolution. The radiation tolerance required the adaption of conceptional design and a stringent selection components.  
 
WEPC19 Toroid Protection System for FLASH simulation, linac, single-bunch, electron 349
 
  • A. Hamdi, F. Ballester, M. Luong, J. Novo
    CEA, Gif-sur-Yvette
  • L. Froehlich, M. Görler, S. Magnus, M. Staack, M. Werner
    DESY, Hamburg
  The FLASH fast machine protection includes a beam loss interlock using toroids to measure the beam charge. This system monitors the beam losses across the whole linac while other protection systems are specifically dedicated to critical components. Four protection modes are used to handle different scenarios of losses: charge validation, single bunch, slice and integration modes. This system is based on 4 ADC’s to sample the top and bottom of upstream and downstream toroid signals. A microcontroller drives 2 programmable delay generators to adjust the top and bottom ADC trigger during the calibration phase. The samples are then collected by a 200Kgates FPGA to process the various protection modes. At first, a VHDL testbench was developed to generate test vectors at the FPGA design inputs. Then, an electronic testbench simulates the linac signals to validate the global hardware functions. Finally, the toroid protection was tested on FLASH with long bunch train at 1 MHz repetition rate.  
 
WEPC27 Segmented Foil SEM Grids for High-Intensity Proton Beams at Fermilab proton, vacuum, booster, radiation 370
 
  • Z. Pavlovic, D. Indurthy, S. E. Kopp, M. Proga, R. M. Zwaska
    The University of Texas at Austin, Austin, Texas
  • B. B. Baller, S. C. Childress, R. D. Ford, D. Harris, C. L.K. Kendziora, C. D. Moore, G. R. Tassotto
    Fermilab, Batavia, Illinois
  The extracted beam transport lines and transfer lines between accelerators at Fermilab must operate at ever higher proton fluences to service the neutrino program and the production of antiprotons for the Tevatron collider program. The high proton fluences place stringent criteria on invasive instrumentation to measure proton beam profiles. Based on a design from CERN, we have built SEM's consisting of Ti foils segmented at either 1.0mm or 0.5mm pitch. The foils are 5um thick Titanium, and two planes of the segmented foils per SEM chamber provides both horizontal and vertical beam profiles. The foil SEM's provide several features over the Au-plated 75 um Ø W-wire SEM's previously in use at Fermilab: (1) a factor 50-60 lower fractional beam loss; (2) greater longevity of Ti signal yield, as compared with W or Au-W; (3) a 'bayonnette'-style frame permitting insertion/retraction from the beam without interruption of operations; and (4) reduced calculated beam-heating from the high-intensity proton-pulses, which results in less sag of the wires/foils. Experience with these detectors after two years' operations in 8 and 120GeV beams will be summarized.