| Paper | Title | Page |
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| WEPEB060 | System Design of Accelerator Safety Interlock for the XFEL/SPring-8 | 2827 |
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The accelerator safety interlock system (ASIS) for the XFEL/SPring-8 protects personnel from radiation hazard. We designed the ASIS consisting of three independent systems; a central interlock system, an emergency interlock system and a beam route interlock system. The central interlock system monitors the machine tunnel security, status of beam line interlock system and radiation monitoring system. The emergency interlock system monitors status of emergency stop buttons. The beam route interlock system monitors electron beam route by inputting the current of the bending magnets at the electron-beam switching points. If any system trips, or if any system detects unsafe status, the permission signal for the accelerator operation from the system is off and the electron beam is inhibited. In addition, it is demanded that the permission signals must be transmitted within 16.6 ms. Therefore, the stability and fast response are required for the XFEL safety interlock system. We adopted programmable logic controllers (PLC) for the stability, and developed optical modules for the fast signal transmission. This paper describes system design of the ASIS. |
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| WEPEB061 | A Fiber Beam Loss Monitor for the SPring-8 X-FEL: Test Operation at the SPring-8 250 MeV Compact SASE Source | 2830 |
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Fiber-based beam loss monitors (BLM) have attracted much attention in recent years. Among them, systems using the detection of the Cerenkov light generated by the secondary charged particles hitting an optical fiber set along the vacuum chamber, offer the possibility to detect beam losses with a very fast response time (less than a few ms) over long distances, good position accuracy and sensitivity at a reasonable cost. For the undulator section of the SPring-8 X-FEL, radiation safety considerations set the desirable detection limit at 1 pC (corresponding to a 0.1% beam loss of the initial 1 nC/pulse) over more than a hundred meter. We report on a the test operation of a fiber-based BLM carried out at the 250 MeV SPring-8 Compact SASE Source (SCSS), a 1/16th model of the future X-FEL. The expected detection limit of the BLM based on a large (400 μm) core multimode fiber is below 2 pC over 120 m (for a corresponding 10 mV signal) while the position accuracy is expected to be better than one meter. |
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| WEPEB062 | Fiber Beam Loss Monitor for the SPring-8 X-FEL: A Numerical Study of its Design and Performance | 2833 |
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A fiber-based beam loss monitors (BLM) is under development for the undulator section of the SPring-8 X-FEL: the system is based on the detection of the Cerenkov light generated by the secondary charged particles hitting an optical fiber set along the vacuum chamber. Various parameters come into account in the final performance of the system, such as the impact angle and energy of the lost electrons, the fiber position (angular and radial) with respect to the point of impact, fiber characteristics (numerical aperture, index, diameter), etc. Thorough numerical studies have been carried out to investigate the performances of the system. Comparison with the experimental results obtained at the SPring-8 Compact SASE Source (SCSS), a 1/16th model of the future X-FEL are also given. |
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| WEPEB063 | Concept of Radiation Monitoring and Safety Interlock Systems for XFEL/SPring-8 | 2836 |
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The accelerator safety interlock system of XFEL/SPring-8 was designed to fulfill the requirement of matching with the safety interlock system of SPring-8 because both safety systems are planning to be unified in near future to deal with the electron beam injection from XFEL to SPring-8. At XFEL, however, additional requirements for the system also existed; the designed radiation shielding requires when the electrons are not injected into the dump core properly, the beam has to be terminated within 16 msec, which corresponds to 60 Hz operation, to avoid the next bunch coming. An outline of such different design criteria is presented together with the concept of the safety interlock system. The radiation monitoring system, which was also the same as that of SPring-8, was installed by reinforcing the redundancy and response time. Gamma and neutron monitors are set at 14 positions near the assumed loss points in the accessible place of the controlled area. The dose equivalent data are sent to the radiation monitoring systems of XFEL and SPring-8, respectively, and when the measured dose exceeds the preset level, an alarm signal is sent to the safety interlock promptly. |
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| WEPEB064 | Electricity Generation from Scattered Secondary Particles Induced by Synchrotron Radiation | 2839 |
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Electricity generation from scattered secondary particles has been examined for a kind of energy-recovery by using a beam loss monitor at the SPring-8 storage ring, in which PIN photodiodes are utilized without a reversed bias voltage in similar to a solar cell. The system and results will be reported. |
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| WEPEB065 | Beam Loss of J-PARC Rapid Cycling Synchrotron at Several Hundred kW Operation | 2842 |
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A 3GeV Rapid-Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC) has continuously provided more than 100kW proton beam to the Neutron target since October 2009. And we also successfully accelerated 300kW beam for one hour on December 10th by way of trial. We found some problems through these experiences. We report those problems and the residual dose in such high intensity operation. |
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| WEPEB066 | Shielding Analyses and Procedures for the SNS | 2845 |
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All stages of the SNS development require significant research and development work in the field of radiological shielding design to assure safety from a radiation-protection point of view for facility operation and to optimize accelerator and target performance. Here we present an overview of on-going shielding work and associated with it procedures and regulations. In the present time, the most of the shielding work is focused on the neutron beam lines and their instrument enclosures in order to commission and provide save operation in the future. This effort is performed according to the guidelines for shielding calculations of SNS neutron beam lines, which sets standards for the analyses and helps to prepare for the Instrument Readiness Review (IRR). The IRR ascertains that the instruments has been design, constructed, and installed to allow safe operation and maintenance. In addition, there is still support for the accelerator facility to redesign parts of the accelerator structures, to design shielding for removed components and test stands for accelerator structures, and for radiation protection analyses for evaluations of accelerator and target safety systems. |
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| WEPEB067 | Beam Containment System for NSLS-II | 2848 |
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The shielding design for the NSLS-II will provide adequate protection for the full injected beam loss in two periods of the ring around the injection point, but the remainder of the ring is shielded for lower losses of <10% full beam loss. This will require a system to insure that beam losses don't exceed these levels for a period of time that could cause levels outside the shield walls. This beam containment system will measure, provide a level of control and alarm indication of the beam power losses along the beam path from the source (e-gun, linac) thru the injection system and the storage ring. This system will consist of collimators that will provide limits to (an potentially measure) the beam miss-steering and control the loss points of the charge and monitors that will measure the average beam current losses along the beam path and alarm when this beam power loss exceeds the level set by the shielding specifications. This will require some new ideas in beam loss detection capability and collimation. The initial planning and R&D program will be presented. |