A Distributed System for Radiation Monitoring at Linear Accelerators

摘要

This paper discusses a system for an on-line neutron fluence monitoring at linear accelerators. The system consists of a SRAM-based detector and a radiation-tolerant read-out system. The neutron fluence was measured in several locations of the accelerator. Monitoring of the radiation environment in an accelerator tunnel is necessary to assure reliable long-term operation of electronic systems placed in the tunnel. Monitoring of the chamber is especially important during the design stage of a linear accelerator. The new design of 20 GeV linear accelerator X-ray Free Electron Laser (X-FEL) is currently approved for construction at DESY Research Centre in Hamburg , . The presented paper is based on our research and experimental measurement carried out at 1.2 GeV superconducting electron linac driving the Vacuum UltraViolet Free Electron Laser (VUV-FEL). The application of a pair of TLD-700 and TLD-500 or superheated emulsion (bubble) dosimeters enables the supervision of neutron fluence in accelerators . This process requires continuous and arduous calibration of TLDs, therefore this method is not convenient. Moreover, it is impossible to monitor the radiation environment in real-time. The presented system fills the market niche of real-time neutron monitoring for high-energy accelerators. Neutron fluence and gamma dose measured in this way can be used for the detailed analysis of the VUV-FEL or X-FEL environments. Monitoring of the radioactive area in a linear accelerator tunnel could be helpful to the diagnosis and reduction of beam losses , . We have conducted experiments with the distributed system dedicated to neutron flux measurement at the DESY Research Centre in Hamburg. The devices were exposed to a neutron field from an Americium-Beryllium$( n,alpha)$source$^241$AmBe. The systems were installed in two accelerators: Linac II and VUV-FEL.