06 Beam Instrumentation, Controls, Feedback, and Operational Aspects
T18 Radiation Monitoring and Safety
Paper Title Page
WEPAF005 A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring 1815
 
  • J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF005  
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WEPAF082 A Systematic Analysis of the Prompt Dose Distribution at the Large Hadron Collider 2036
 
  • O. Stein, K. Bilko, M. Brugger, S. Danzeca, D. Di Francesca, R. Garcia Alia, Y. Kadi, G. Li Vecchi, C. Martinella
    CERN, Geneva, Switzerland
 
  During the operation of the Large Hadron Collider (LHC) the continuous particle losses create a mixed particle radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects. In order to achieve an optimal lifetime associated to radiation damage, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Based on the continuous analysis of the data from more than 3900 ionisation chamber beam loss monitors the evolution of the radiation levels is monitored during the accelerator operation. Normalising the radiation fields with either the integrated luminosity or the integrated intensities allows extrapolating the radiation levels of future accelerator operation. In this paper, the general radiation levels in the arcs and the insertion regions at the LHC and their evolution will be presented. The changes in the prompt dose distribution along the LHC between the operation in 2016 and 2017 will be discussed. The impact of different accelerator settings on the local dose distribution will be addressed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF082  
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WEPAF083 Distributed Optical Fiber Radiation Sensing at CERN 2039
 
  • G. Li Vecchi, M. Brugger, S. Danzeca, D. Di Francesca, R. Ferraro, Y. Kadi, O. Stein
    CERN, Geneva, Switzerland
  • S. Girard
    Univ-Lyon Laboratoire H. Curien, UMR CNRS 5516, Saint Etienne, France
 
  The CERN's accelerator tunnels are associated with very complex mixed field radiation environments. Radiation degrades electronic components and directly affects their lifetimes causing failures that contribute to the machine downtime periods. In our contribution, we will report on the development and first employment of a Distributed Optical Fiber Radiation Sensor (DOFRS) at CERN. The most interesting feature of DOFRS technology is to provide an online and spatially distributed map of the dose levels in large machines with spatial resolution of the order of one meter. This fiber based dose sensor will provide valuable information in addition to the currently installed active and passive dosimeters. After demonstrating the working principle of DOFRS*, the first operational prototype was installed in the Proton Synchrotron Booster during last 2016/17 end-of-the-year technical stop. The DOFRS has been acquiring data successfully since the beginning of 2017 operations. The performances that were achieved by the first prototype will be discussed in the final contribution. The DOFRS measurements will also be bench-marked to the results provided by other punctual dosimeters.
*I. Toccafondo et al., 'Distributed Optical Fiber Radiation Sensing in a Mixed-Field Radiation Environment at CERN,' J. Lightw. Technol. 35, 3303, 3310, 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF083  
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WEPAK001 Intense Neutrino Source Front End Beam Diagnostics System R&D 2077
 
  • K. Yonehara, M.D. Balcazar, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  • M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
    Muons, Inc, Illinois, USA
 
  Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
We overview the front end beam diagnostic system R&D to prepare operation of a multi-MW proton beam for intensity frontier Neutrino experiments. One of critical issues is shorter life time of a detector with higher beam intensity due to radiation damage. We show a possible improvement of the existing ion chamber based detector, and a study of a conceptually new radiation-robust detector which is based on a gas-filled RF resonator.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK001  
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WEPAL002 Improvement of Personnel and Machine Protection System in Superkekb Injector Linac 2140
 
  • I. Satake, H. Honma, A. Shirakawa, N. Toge
    KEK, Ibaraki, Japan
 
  Since summer of 2010, the radiation control area for the KEK electron positron injector linac had been split at the around 3 GeV point by a concrete wall into upstream and downstream parts with independent beam sources. This was so as to allow operation of the downstream part for beam injection into photon factory rings while construction and development of new electron guns proceed in the upstream part. In summer of 2017, this arrangement was revised and the entire injector linac was reconsolidated into a single radiation control area. This was in conjunction with the introduction of the 1.1 GeV positron damping ring for Phase-II operation of SuperKEKB and successful development of new electron RF guns in the far upstream part of the linac. Along with this reconsolidation, the personnel and machine protection system was modified and improved. Interlock signal lines for the damping ring and RF guns were added. The operation panel of the main console was modified accordingly. In addition, the screen displays of the interlock status were updated. In this paper we report on the renewed system of KEK injector linac in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL002  
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WEPAL058 Beam Loss Studies at the Taiwan Photon Source 2309
 
  • C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
 
  PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL058  
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THPML140 Radiation Monitoring System of HLSII 5011
 
  • Lin, H.S. Lin, Y.Q. Cai, S.P. Jiang, Z.B. Sun, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China 11675170 By the Fundamental Research Funds for the Central Universities WK2310000056
Monitoring of ionizing radiation of synchrotron radiation facility is very important for the safety of staff and users of the light source. Radiation monitoring system of HLSII has been built and the whole system consists of local radiation monitoring spots and central control system, and a web-based monitoring dynamic release system. The local radiation monitoring spot consists of a high air pressure ionization type gamma detector and a BF3 counting tube neutron detector, and the radiation data are calculated by microcontroller locally and acquired by the data server for further processing. The dynamic release system is integrated with EPICS interface and radiation safety interlock system. Other accelerator systems could obtain radiation data from the server and the interlock system is triggered by the radiation data to shut down the machine in case the radiation exceeds the safety threshold.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML140  
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