Beam Loss Detection
Paper Title Page
MOPG19 Diamond Monitor Based Beam Loss Measurements in the LHC 82
 
  • C. Xu, B. Dehning, F.S. Domingues Sousa
    CERN, Geneva, Switzerland
  • E. Griesmayer
    CIVIDEC Instrumentation, Wien, Austria
 
  Two pCVD diamond based beam loss monitors (dBLM) are installed near the primary collimators of the LHC, with a dedicated, commercial readout-system used to acquire their signals. The system is simultaneously able to produce a high sampling rate waveform and provide a real-time beam loss histogram for all bunches in the machine. This paper presents the data measured by the dBLM system during LHC beam operation in 2016.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG19  
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MOPG20 Optimized Beam Loss Monitor System for the ESRF 86
 
  • K.B. Scheidt, F. Ewald
    ESRF, Grenoble, France
  • P. Leban
    I-Tech, Solkan, Slovenia
 
  Monitoring of the 6 GeV electron losses around the ESRF storage ring is presently done by a hybrid system consisting of ionization chambers and scintillators. It allows a rough localization of the losses, but has numerous limitations : size, weight, time-resolution, sensitivity, versatility, and costs. A new system was developed consisting of a detector head (BLD) and the electronics for signal acquisition and control (BLM). The BLD is compact, based on a scintillator coupled to a small photo-multiplier module. The BLM controls 4 independent BLDs and acquires data with sampling rates up to 125 MHz. Measurements performed on different configurations of BLD prototypes have lead to an optimized design that allows, together with the flexible signal processing performed in the BLM, to cover a wide range of applications: measurement of fast and strong losses during injection is just as well possible as detection of very small variations of weak losses during the slow current decay. This paper describes the BLD/BLM design, its functionality and performance characteristics, and shows results from prototypes installed in the injection zone and in close vicinity to in-vacuum undulators.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG20  
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MOPG21 Development of a Method for Continuous Functional Supervision of BLM Systems 90
 
  • C.F. Hajdu, C. Zamantzas
    CERN, Geneva, Switzerland
  • T. Dabóczi, C.F. Hajdu
    BUTE, Budapest, Hungary
 
  It is of vital importance to provide a continuous and comprehensive overview of the functionality of beam loss monitoring (BLM) systems, with particular emphasis on the connectivity and correct operation of the detectors. At CERN, a new BLM system for the pre-accelerators of the LHC is currently at an advanced stage of development. This contribution reports on a new method which aims to automatically and continuously ensure the proper connection and performance of the detectors used in the new BLM system.  
poster icon Poster MOPG21 [0.337 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG21  
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MOPG22 Studies and Historical Analysis of ALBA Beam Loss Monitors 94
 
  • A.A. Nosych, U. Iriso
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  During 5 years of operation in the 3 GeV storage ring of ALBA, the 124 beam loss monitors (BLM) have provided stable measurements of relative losses around the machine, with around 10% breakdown of units. We have analyzed these BLM failures and correlated the integrated received dose with any special conditions of each BLM location which might have led to their breakdown. We also show studies of beam losses in the insertion devices, with particular attention to the results in the multipole wiggler (MPW), where the vacuum chamber is (suspected to be) misaligned and high BLM counts are detected.  
poster icon Poster MOPG22 [16.015 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG22  
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TUAL02 A New Beam Loss Monitor Concept Based on Fast Neutron Detection and Very Low Photon Sensitivity 277
 
  • J. Marroncle, A. Delbart, D. Desforge, C.L.H. Lahonde-Hamdoun, Ph. Legou, T. Papaevangelou, L. Segui, G. Tsiledakis
    CEA/IRFU, Gif-sur-Yvette, France
 
  Superconductive accelerators may emit X-rays and Gammas mainly due to high electric fields applied on the superconductive cavity surfaces. Indeed, electron emissions will generate photons when electrons impinge on some material. Their energies depend on electron energies, which can be strongly increased by the cavity radio frequency power when it is phase-correlated with the electrons. Such photons present a real problem for Beam Loss Monitor (BLM) systems since no discrimination can be made between cavity contributions and beam loss contributions. Therefore, a new BLM is proposed which is based on gaseous Micromegas detectors, highly sensitive to fast neutrons, not to thermal ones and mostly insensitive to X-rays and Gammas. This detector uses Polyethylene for neutron moderation and the detection is achieved using a 10B or 10B4C converter film with a Micromegas gaseous amplification. Simulations show that detection efficiencies > 8 % are achievable for neutrons with energies between 1 eV and 10 MeV.  
slides icon Slides TUAL02 [1.248 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUAL02  
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TUAL03 Beam Loss and Abort Diagnostics during SuperKEKB Phase-I Operation 282
 
  • H. Ikeda, J.W. Flanagan, H. Fukuma, T. Furuya, M. Tobiyama
    KEK, Ibaraki, Japan
 
  Beam commissioning of SuperKEKB Phase-I started in Feb., 2016. In order to protect the hardware components of the accelerator against unstable Ampere class beams, the controlled beam abort system was upgraded. Because of the higher beam intensity and shorter beam lifetime than at the original KEKB, a beam abort monitor system is important for machine tuning and the safety of the components. The system collected the data of all aborts of more than 1000 in this operation period, and we diagnosed not only the hardware performance but the tuning software by analyzing the relations between beam current, loss monitor signals and RF cavity voltages. This paper will give the outline of the monitoring system, and will present typical examples of signal and diagnoses.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUAL03  
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TUPG20 The CMS Beam Halo Monitor at the LHC: Implementation and First Measurements 364
 
  • N. Tosi
    INFN-Bologna, Bologna, Italy
 
  A Cherenkov based detector system has been installed at the Large Hadron Collider (LHC), in order to measure the Machine Induced Background (MIB) for the Compact Muon Solenoid (CMS) experiment. The system is composed of forty identical detector units formed by a cylindrical Quartz radiator directly coupled to a Photomultiplier. These units are installed at a radius of 1.8m and a distance of 20.6 m from the CMS interaction point. The fast and direction-sensitive signal allows to measure incoming MIB particles while suppressing the much more abundant collision products and albedo particles, which reach the detector at a different time and from a different direction. The system readout electronics is based on the QIE10 ASIC and a uTCA based back-end, and it allows a continuous online measurement of the background rate separately per each bunch. The detector has been installed in 2015 and is now fully commissioned. Measurements demonstrating the capability of detecting anomalous beam conditions will be presented.
on behalf of the CMS collaboration
 
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG20  
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TUPG21 Beam-Loss Monitoring Signals of Interlocked Events at the J-PARC Linac 368
 
  • N. Hayashi, Y. Kato, A. Miura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
 
  It is important to understand why the beam gets lost during normal operation. If RF cavity gets interlocked due to its failure, it is understandable. But it is still useful to study its detail mechanism and which beam loss monitor (BLM) receives higher loss or it is more sensitive in order to reduce a numbers of interlocked events and stabilize the accelerator operation in future. The J-PARC Linac BLM has a simple data recorder system consists of multi-oscilloscopes. Although its functionality is limited, it can record events when an interlock is triggered. Particular interest is the events associate with only BLM MPS (Machine-Protection-System). They may reveal hidden problems in the accelerator.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG21  
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TUPG22 Timing Window and Optimization for Position Resolution and Energy Calibration of Scintillation Detector 372
 
  • J. Zhu, M.H. Fang, J. Wang, Z.Y. Wei
    NUAA, Nanjing, People's Republic of China
 
  The real event selection, timing resolution, position resolution and energy response of the EJ-200 plastic scintillation detector have been analyzed using timing window coincidence measurement. The detector was simulated based on Monte Carlo, including its geometry, energy deposition, photon collection and signal generation. The detection efficiency and the real events selection have been obtained while the background noise has been reduced by using two-end readout timing window coincidence. We developed an off-line analysis code, which is suitable for massive data from the digitizer. We set different coincidence timing windows, and did the off-line data processing respectively. We find the detection efficiency increases as the width of the timing window increases, and when the width of timing window is more than 10ns, the detection efficiency will slowly grow until it reaches saturation. Time, position and energy response have been measured by exposing to radioactive sources. The best timing window parameter as 16ns is obtained for on-line coincidence measurement, and the position resolution is up to 12cm. Energy response of the detector was linear within the experimental energy range*.
* L. Karsch, A. Bohm et al,"Design and Test of A Large-area Scintillation Detector for Fast Neutrons", Nuclear Instruments and Methods in Physics Research A, vol.460, pp.362-367, 2001.
 
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG22  
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TUPG23 Use CR-39 Plastic Dosimeters for Beam Ion Halo Measurements 376
 
  • I. Eliyahu, A. Cohen, E. Daniely, B. Kaizer, A. Kreisler, A. Perry, A. Shor, L. Weissman
    Soreq NRC, Yavne, Israel
 
  Beam halo and growth of beam emittance are important issues for high-intensity linear accelerators. Beam-dynamic predictions of weak beam tails are usually not reliable due to complexity of the non-linear effects leading to halo formation. Therefore, development of a simple method for beam halo diagnostics is highly desirable. The first testing of CR-39 solid-state nuclear track dosimeters for beam halo measurement were performed at the SARAF phase I accelerator with a few MeV proton beams. Beam pulses of 90 nA peak intensity of shortest possible duration (15 ns) were used for direct irradiation of standard CR-39 personal dosimetry tags. Other irradiations were done with beam pulses of 200 ns duration and of 1 mA peak intensity. Specially prepared large area CR-39 plates with central hole for the beam core transport were used in these tests. Weak beam structures were clearly observed in the both types of irradiation. The tests showed feasibility of beam halo measurements down to resolution level of a single proton. The optimum CR-39 etching conditions were established. The advantages and drawback of the method are discussed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG23  
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TUPG24 Online Total Ionisation Dosimeter (TID) Monitoring Using Semiconductor Based Radiation Sensors in the ISIS Proton Synchrotron 379
 
  • D.M. Harryman, A. Pertica
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  During routine operation, the radiation levels in the ISIS proton synchrotron become high enough to permanently affect systems and electronics. This can potentially cause critical components to fail unexpectedly or denature over time, causing disruption for users of the ISIS facility or a loss of accuracy on a number of systems. To study the long term effects of ionising radiation on ISIS systems and electronics, the total dose received by such components must be recorded. A semiconductor based online Total Ionisation Dosimeter (TID) was developed to do this, using pin diodes and Radiation sensing Field Effect Transistors (RadFETs) to measure the total ionisation dose. Measurements are made by feeding the TIDs with a constant current, with the threshold voltage on each device increasing in relation to the amount of radiation that it has received. This paper will look at preliminary offline results using off the shelf Field Effect Transistors (FETs) and diodes, before discussing the development of the RadFET online monitor and the results it has gathered thus far. Finally the paper will look at future applications and studies that this type of monitor will enable.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG24  
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WEPG19 Conceptual Design of LEReC Fast Machine Protection System 665
 
  • S. Seletskiy, Z. Altinbas, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, L.R. Hammons, J. Hock, P. Inacker, J.P. Jamilkowski, D. Kayran, K. Mernick, T.A. Miller, M.G. Minty, M.C. Paniccia, I. Pinayev, K.S. Smith, P. Thieberger, J.E. Tuozzolo, W. Xu, Z. Zhao
    BNL, Upton, Long Island, New York, USA
 
  The low energy RHIC Electron Cooling (LEReC) accelerator will be running with electron beams of up to 110 kW power with CW operation at 704MHz. Although electron energies are relatively low (< 2.6MeV), at several locations along the LEReC beamline, where the electron beam has small (about 250 um RMS radius) design size, it can potentially hit the vacuum chamber at a normal incident angle. The accelerator must be protected against such a catastrophic scenario by a dedicated machine protection system (MPS). Such an MPS shall be capable of interrupting the beam within a few tens of microseconds. In this paper we describe the current conceptual design of the LEReC MPS.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG19  
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WEPG20 An Optical Fibre BLM System at the Australian Synchrotron Light Source 669
 
  • M. Kastriotou, E.B. Holzer, E. Nebot Del Busto
    CERN, Geneva, Switzerland
  • M.J. Boland
    The University of Melbourne, Melbourne, Victoria, Australia
  • M. Kastriotou, E. Nebot Del Busto, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • M. Kastriotou, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Increasing demands on high energy accelerators are triggering R&D into improved beam loss monitors with a high sensitivity and dynamic range and the potential to efficiently protect the machine over its entire length. Optical fibre beam loss monitors (OBLMs) are based on the detection of Cherenkov radiation from high energy charged particles. Bearing the advantage of covering more than 100m of an accelerator with only one detector and being insensitive to X-rays, OBLMs are ideal for electron machines. The Australian Synchrotron comprises an 100 MeV 15m long linac, an 130m circumference booster synchrotron and a 3 GeV, 216m circumference electron storage ring. The entire facility was successfully covered with four OBLMs. This contribution summarises a variety of measurements performed with OBLMs at the Australian Synchrotron, including beam loss measurements during the full booster and measurements of steady-state losses in the storage ring. Different photosensors, namely Silicon Photo Multipliers (SiPM) and fast Photo Multiplier Tubes (PMTs) have been used and their respective performance limits are discussed.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG20  
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WEPG22 Relation between Signals of the Beam Loss Monitors and Residual Radiation in the J-PARC RCS 673
 
  • M. Yoshimoto, H. Harada, M. Kinsho, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The most important issue in realizing such a MW-class high-power routine beam operation is to keep machine activations within a permissible level, that is, to preserve a better hands-on-maintenance environment. Thus, a large fraction of our effort has been concentrated on reducing and managing beam losses. To validate the beam loss optimizations, residual radiation measurement along the ring provide us with further information. By relating signals of the beam loss monitors with the measured distribution of the residual radiation, achievements of the high power beam operation will be described. In this presentation, we will report on the measurement results of residual radiation distribution along the ring together with the relation with the beam loss signals.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG22  
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WEPG23 Evaluating Beam-Loss Detectors for LCLS-2 678
 
  • A.S. Fisher, R.C. Field, L.Y. Nicolas
    SLAC, Menlo Park, California, USA
 
  The LCLS x-ray FEL occupies the third km of the 3-km SLAC linac, which accelerates electrons in copper cavities pulsed at 120 Hz. For LCLS-2, the first km of linac will be replaced with superconducting cavities driven by continuous RF at 1300 MHz. The normal-conducting photocathode gun will also use continuous RF, at 186 MHz. The laser pulse rate will be variable up to 1 MHz. With a maximum beam power of 250 kW initially, and eventually 1 MW, the control of beam loss is critical for machine and personnel safety, especially since losses can continue indefinitely in linacs and dark current emitted in the gun or cavities can be lost at any time. SLAC protection systems now depend on ionization chambers, both local devices at expected loss sites and long gas-dielectric coaxial cables for distributed coverage. However, their ion collection time is over 1 ms, far slower than the beam repetition rate. We present simulations showing that with persistent losses, the space charge of accumulated ions can null the electric field inside the detector, blinding it to an increase in loss. We also report on tests comparing these detectors to faster alternatives.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG23  
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