Beam Loss Detection
Paper Title Page
MOPB018 Data Acquisition System for SuperKEKB Beam Loss Monitors 1
  • M. Tobiyama, J.W. Flanagan, H. Ikeda
    KEK, Ibaraki, Japan
  The monitoring of the beam loss distribution along the accelerator is important in order to prevent damage of the vacuum components, and, in addition, to suppress the unnecessary irradiation of the accelerator elements. As it is not easy to construct the readout system to be synchronised to a fast timing signal, such as beam injection, a new 64-ch ADC system has been developed that samples the output of the loss monitor signal integrator with a fairly fast rate and automatically keeps the peak, mean and minimum of the data. The performance of the ADC system will be shown. The control system configuration that reads and resets the hardware interlock signal from the loss monitor signal integrator for the machine protection system (MPS) will also be presented.  
poster icon Poster MOPB018 [0.297 MB]  
Residual Radiation Measurements by Beam Loss Monitors at J-PARC Main Ring  
  • T. Toyama, K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • H. Kuboki, M.J. Shirakata, B. Yee-Rendón
    KEK, Tokai, Ibaraki, Japan
  In J-PARC (the Japan Proton Accelerator Research Complex), a high intensity proton accelerator, controlling and localising beam losses and residual radiations are a key issue, because the residual radiation limits maintenance work in efficiency, working hours, and machine availability. To step forward we began continuous measurement of residual radiation after beam shutdown using beam loss monitors in the Main Ring (MR). Wire cylinder gaseous radiation detectors are used in a proportional counting region. The heads are DC-connected and have a gain as large as 30000 with a bias of 2 kV. We change the DAQ trigger and the gain as soon as the accelerator operation ends. The offsets are measured with a zero bias voltage. We could identify some radionuclides from the time evolution of the dose by performing a comparison to simulation. Accumulation of long lived radionuclides and future workability are expected from this data.  
MOPB021 Signal Response of the Beam Loss Monitor as a Function of the Lost Beam Energy 1
  • K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  The J-PARC 3 GeV rapid cycling synchrotron (RCS) accelerates a proton beam up to 3GeV and delivers it to the main ring and the Material and Life Science Experimental Facility. The injection energy of the RCS was 181 MeV since 2013, and it was upgraded to 400 MeV in 2014. Main magnets (dipole and quadrupole magnets) of the RCS have large aperture, and thickness of yoke is larger than 200 mm. Considering the stopping power of a proton, the shielding effect of the magnets strongly depends on the lost beam energy. When the beam loss occurs during injection, the lost proton cannot penetrate the magnet yoke. But when the beam loss occurs after acceleration, the lost beam easily passes the magnet. Therefore the signal response of the beam loss monitor is changed even if the loss power is the same. To evaluate the amount of the lost particles from BLM response, we estimated the signal dependence on the lost energy from simulation.  
MOPB030 Time Measurement Method Based on CPLD for Beam Loss Position Monitor 1
  • Y. Yang, Y.B. Leng, Y.B. Yan
    SSRF, Shanghai, People's Republic of China
  Beam loss position is of great concern at SSRF. Time measurement is one of the key technologies for beam loss position monitor. This paper introduces a time measurement method based on Complex Programmable Logic Device (CPLD). Simulation has been done to verify the performance of this method.  
Beam Instrumentation for Protection of the ESS Linac  
  • T.J. Shea, C. Darve, M. Donna, H. Hassanzadegan, A. Jansson, M. Jarosz, I. Kittelmann, A. Nordt
    ESS, Lund, Sweden
  The European Spallation Source (ESS) linac will accelerate protons to 2 GeV in pulses 2.86 ms long with a peak current of 62.5 mA, ultimately producing a 5 MW beam. Because this beam presents a formidable threat to the superconducting cavities and other accelerator components, the impact of errant beam conditions has been evaluated with Monte Carlo simulations and thermo-mechanical analysis. These studies inform the requirements for the beam instrumentation systems tasked with protecting the accelerator. Throughout the linac, the beam current monitors will detect any significant beam loss or deviation from the intended beam current patterns. At the low energy end, neutron detectors will detect the loss of low energy protons while at the high energy end, ionisation chambers will do the same. Detection of errant conditions will result in the suppression beam production within tens of microseconds. This paper will review technical design choices that should minimise the probability of damage and activation while maximising machine availability. Anticipated technical challenges will also be discussed.  
MOPB042 Beam Loss Monitors for the Cryogenic LHC Magnets 1
  • M.R. Bartosik, A. Alexopoulos, B. Dehning, M. Sapinski
    CERN, Geneva, Switzerland
  • V. Eremin, E. Verbitskaya
    IOFFE, St. Petersburg, Russia
  • E. Griesmayer
    CIVIDEC Instrumentation, Wien, Austria
  Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485.
The Beam Loss Monitoring system of the Large Hadron Collider close to the interaction points contains mostly gas ionization chambers working at room temperature, located far from the superconducting coils of the magnets. The system records particles lost from circulating proton beams, but is also sensitive to particles coming from the experimental collisions, which do not contribute significantly to the heat deposition in the superconducting coils. In the future, with beams of higher brightness resulting in higher luminosity, distinguishing between these interaction products and dangerous quench-provoking beam losses from the circulating beams will be difficult. It is proposed to optimise by locating beam loss monitors inside the cold mass of the magnets, housing the superconducting coils, in a superfluid helium environment, at 1.9 K. This contribution will present results of radiation hardness test of p+-n-n+ silicon detectors which, together with single crystal Chemical Vapour Deposition diamond, are the main candidates for these future cryogenic beam loss monitors.
BLM Crosstalk Studies at the CLIC Two-Beam Module  
  • M. Kastriotou, S. Döbert, F.S. Domingues Sousa, E. Effinger, W. Farabolini, E.B. Holzer, E. Nebot Del Busto, W. Viganò
    CERN, Geneva, Switzerland
  • 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
  The Compact Linear Collider (CLIC) is a proposal for a future linear e+-e accelerator that can reach 3 TeV centre of mass energy. It is based on a two-beam acceleration scheme, with two accelerators operating in parallel. One of the main CLIC elements is a 2 m long two-beam module where power from a high intensity, low energy drive beam is extracted through Power Extraction and Transfer Structures (PETS) and transferred as RF power for the acceleration of the low intensity, high energy main beam. One of the main potential limitations for a Beam Loss Monitoring (BLM) system in a two-beam accelerator is so-called 'crosstalk', i.e. signals generated by losses in one beam, but detected by a monitor protecting the other beam. This contribution presents results from comprehensive studies into crosstalk that have been performed at a two-beam module at the CLIC Test Facility (CTF3) at CERN. The capability of estimating the origin of losses for different scenarios is also discussed.  
MOPB051 System Integration of SwissFEL Beam Loss Monitors 1
  • P. Pollet, R. Ischebeck, D. Llorente Sancho, G. Marinkovic, C. Ozkan Loch, V. Schlott
    PSI, Villigen PSI, Switzerland
  Scintillator-based Beam Loss Monitors will be used at SwissFEL for monitoring the losses for optimising beam conditioning, beam measurements with the wire-scanner and Undulator protection. The optical signals from the scintillators will be detected by PMTs which are located outside the accelerator tunnel. The PMT control and signal conditioning is done via a front-end based on the PSI Analogue Carrier board. The PAC board allows for amplification/attenuation, offsetting and single-ended to differential conversion, while the Generic PSI Carrier (GPAC) board provides digitisation and FPGA-based post-processing, along with bridging the communication to EPICs controls. A fast algorithm was developed to process the signals and trigger the machine protection system (MPS) at 100Hz. The system integration of the BLMs and its results will be discussed in this paper.  
MOPB053 The Beam Loss Monitoring System in Taiwan Photon Source 1
  • C.H. Huang, J. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
  Taiwan photon source (TPS) is a 3rd generation and 3 GeV synchrotron light source during beam commissioning in NSRRC. Several types of beam loss monitors (BLMs) such as PIN-photodiodes, scintillation detectors, cherenkov BLMs and RadFETs are installed in the storage ring to study the beam loss distribution and mechanism. The installation infrastructure, design of reader units and integrated graphic user interface will be described in this report. The primary experimental results will also be summary here.  
poster icon Poster MOPB053 [0.656 MB]  
MOPB057 Observation of Beam Loss Signal at the SPS Storage Ring 1
  • S. Krainara, G.G. Hoyes, P. Klysubun, S. Kongtawong, P. Sudmuang, N. Suradet, S. Teawphet
    SLRI, Nakhon Ratchasima, Thailand
  Beam Loss Monitoring (BLM) system is an essential tool for observing beam instabilities and hence for machine protection. At the Siam Photon Source (SPS) storage ring, the BLM system is used to check the beam behavior due to optics perturbation, ion trapping, and vacuum leakage. A network of 50 PIN-diode detectors from Bergoz has been installed around the ring at the positions of high particle density. These positions are at the values of large betatron and dispersion functions in the machine lattice. The operational results of tune scanning verses loss rate in the resonance diagram are described. These results will be useful for improving the beam performance in terms of lifetime and beam stability.  
poster icon Poster MOPB057 [5.516 MB]  
MOPB058 Improvement of the Siam Photon Source Beam Loss Monitor System 1
  • N. Suradet, G.G. Hoyes, P. Klysubun, S. Krainara, P. Sudmuang, S. Teawphet
    SLRI, Nakhon Ratchasima, Thailand
  A description of the newly re-built beam loss monitor (BLM) system at the Siam Photon Source (SPS) is presented. The original BLM system was designed and installed in the 1.2 GeV SPS storage ring in 2005. The main problems of this system were poor performance due to RF electromagnetic interference and the use of now obsolete data acquisition electronics. The beam loss detector used is a PIN-diode type from Bergoz. The new BLM system has been implemented using low-noise coaxial cable and an acquisition system based on NI-PXI. The hardware and software modifications incorporated into the new BLM system are presented.  
poster icon Poster MOPB058 [3.473 MB]  
FLUKA Studies of Beam Loss Diagnostics on ISIS  
  • H. V. Smith
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  The ISIS facility at the Rutherford Appleton Laboratory is a pulsed neutron and muon source for materials and life science research. Up to 3×1013 protons per pulse are accelerated to 800 MeV in the ISIS 50 Hz RCS. The maximum operating intensity of the synchrotron is limited by loss during acceleration. A suite of beam loss diagnostics is available for use on ISIS, comprising argon ionisation tubes on the inner radius of the synchrotron and organic scintillators on the inner radius of the dipole ceramic vacuum vessels. This paper introduces initial studies of these operational diagnostics with the FLUKA code: measurements of the position sensitivity of the argon ionisation tubes have been compared to simulations to increase understanding of the observed loss distributions, comparisons of the response of argon ionisation tubes and scintillator have been made, and an existing model of the ISIS collimation system has been extended and benchmarked against machine measurements in order to optimise the collimator positions.  
MOPB070 FRIB Machine Protection System Design and Validation Studies 1
  • S.M. Lidia, M. Ikegami, Z. Li, Z. Liu, T. Russo, R.C. Webber, Y. Zhang, Q. Zhao
    FRIB, East Lansing, Michigan, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
The FRIB heavy ion superconducting linac will present the highest peak power hadron beam facility, with beams carrying >400 kW power with kinetic energy >200 MeV/u. Fast protection systems are required to detect and remove beam within 35 us. Detection of beam losses in the low energy linac segment is confounded by two effects: small fluxes of secondary radiation from beam impacts, and large fluxes due to cross-talk from neighbouring, higher energy linac sections. We describe a machine protection scheme based on multiple families of diagnostics and diagnostic networks. On-going fault mode studies are utilised to assess risk and to assist in the definition of specific detection networks for high reliability and responsivity.
MOPB073 Cryogenic Thermometers as Slow Beam Loss Detectors 1
  • Z. Zheng, Z.Q. He, S.M. Lidia, Z. Liu, R. Shane, Y. Zhang
    FRIB, East Lansing, Michigan, USA
  Due to the folded geometry of the linac, beam loss monitoring at the Facility for Rare Isotope Beams (FRIB) [1], especially for small losses, is extremely challenging in the low energy section of the linac. Fast detection is not required for slow/small beam losses, and we therefore propose thermometers installed in the cryomodules at potential hot spots, such as the locations upstream of solenoids. Cryogenic thermometry tests were implemented in the ReA6 cryomodule with heaters and RTD thermometers. The preliminary study shows that the 10 mK signal resolution of thermometers corresponds to ~5 mW heat power in 100 seconds, or ~1 W heat power in 10 seconds, which is sufficient to satisfy the requirement for small beam loss at FRIB.  
Radiation Damage Considerations in Accelerator Beam Environments  
  • D. Webb
    ARPANSA, Yallambie, Australia
  The impact of radiation upon equipment used on accelerator beam lines is a continuing concern. Materials, cabling and instrumentation will experience aging and degradation and even failure depending on the nature of the radiation and the intensity of the fields. This discussion will review the fundamentals of radiation interactions and look at possible mechanisms for damage. In the case of electron accelerators producing photon beams, ionization effects will tend to dominate but if the energies are high enough, secondary charged particles and neutrons are created that can cause atomic displacements and even impurity production. We can also distinguish between cumulative effects and single event effects. For instrumentation, the topic of radiation damage can be divided into electromagnetic and bulk damage components. Hadrons can also produce bulk damage. Strategies to minimise or delay the effects of radiation damage need to take these issues into account. Some examples will be discussed.  
slides icon Slides WEALA01 [7.736 MB]  
Beam Loss Monitoring for Demanding Environments  
  • E.B. Holzer
    CERN, Geneva, Switzerland
  Beam loss monitoring (BLM) is a key protection system for machines using beams with damage potential and is an essential beam diagnostic tool for any machine. All BLM systems are based on the observation of secondary particle showers originating from escaping beam particles. With ever higher beam energies and intensities, the loss of even a tiny fraction of the beam can lead to damage or, in the case of superconducting machines, quenches. Losses also lead to material ageing and activation and should therefore be well controlled and reduced to a minimum. The ideal BLM system would have full machine coverage and the capability to accurately quantify the number of lost beam particles from the measured secondary shower. Position and time resolution, dynamic range, noise levels and radiation hardness all have to be considered, while at the same time optimising the system for reliability, availability and maintainability. This contribution will focus on design choices for BLM systems operating in demanding environments, with a special emphasis on measuring particle losses in the presence of synchrotron radiation and other background sources.  
slides icon Slides WEBLA01 [5.030 MB]  
Development of the Beam Loss Monitor for Beam Halo Measurement in the J-PARC RCS  
  • M. Yoshimoto, H. Harada, S. Kato, M. Kinsho, K. Okabe
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  In the J-PARC RCS, transverse beam profiles including both the beam core and halo at the extraction beam transport line (3NBT) were measured by using a combination with a wire scanner type beam scraper and beam loss monitors (BLMs). Our final goal of this halo monitor is to measure the intra-bunch beam halo of extracted two bunches from the RCS. Thus the plastic scintillator and photomultiplier (PMT) assemblages were adopted as the BLMs with quick time response. However, we found that the BLMs detected not only the radiation from the wire but also the reflected radiation from other devices and walls. Therefore we tried to develop new-type BLMs, which are scintillation-type BLM with lead glass and Cherenkov-type BLM with quartz or UV acrylic. In this presentation, we will present an overview and experimental results of the new-type BLMs together with an outline of halo monitor system.  
slides icon Slides WEBLA02 [5.594 MB]  
WEBLA03 Position Resolution of Optical Fibre-Based Beam Loss Monitors Using Long Electron Pulses 1
  • E. Nebot Del Busto, S. Döbert, F.S. Domingues Sousa, E. Effinger, W. Farabolini, E.B. Holzer, M. Kastriotou, W. Viganò
    CERN, Geneva, Switzerland
  • M.J. Boland
    ASCo, Clayton, Victoria, Australia
  • M.J. Boland
    SLSA, Clayton, Australia
  • M.J. Boland, R.P. Rassool
    The University of Melbourne, Melbourne, Victoria, Australia
  • W. Farabolini
    CEA/DSM/IRFU, France
  • M. Kastriotou, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Kastriotou, E. Nebot Del Busto, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  Beam loss monitoring systems based on optical fibres (oBLM), have been under consideration for future colliders for several years. To distinguish losses between consecutive quadrupoles, a position resolution of less than 1 m is required. A resolution of better than 0.5 m has been achieved in machines with single, nanosecond long pulses. For longer beam pulses, such as the ~150 ns CLIC pulse, the longitudinal length of signals in the fibre is close to the duration of the beam pulse itself which makes loss reconstruction very challenging. In this contribution, results from experiments into the position resolution of an oBLM based on long beam pulses are presented. These measurements have been performed at the CLIC Test Facility (CTF3) and the Australian Synchrotron Light Source (ASLS). In CTF3, controlled beam losses were created at different quadrupoles in the 28 m long decelerating Test Beam Line (TBL) LINAC by altering the current supplied or misaligning them. In ASLS the flexibility of the facility allowed the location of beam losses generated by single bunches to be studied as well as losses for longer bunch trains up to 600 ns in duration.  
slides icon Slides WEBLA03 [2.105 MB]