A Distributed System for Radiation Monitoring at Linear Accelerators

Abstract

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 accel- erator. 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 [1], [2]. 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 [3]. 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 [4], [5]. 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 ) source 241 AmBe. The systems were installed in two accelerators: Linac II and VUV-FEL.Index Terms-Linear accelerator, neutron fluence, single event effect, single event upset, static random access memory.

Prototype Real-Time ATCA-Based LLRF Control System

“…The module equipped with gamma and neutron radiation detectors allows to estimate doses absorbed by the LLRF hardware. A RadFET detector is used for gamma dosimetry, whereas a Static Random Access Memory (SRAM) chip is applied as a reference error counter or neutron fluence detector when it is calibrated [28], [29].…”

Radiation monitoring system for X-FEL

“…A large number of miscellaneous memories were examined with the application of a calibrated 241 AmBe(α, n) americium-beryllium neutron source to select the most suitable SRAM as a neutron dosimeter. Auxiliary irradiations were performed initially in the Linac II and the FLASH accelerator tunnels [4].…”

“…A few different versions of RadMon readout were designed and examined, while SRAM devices were being tested [4,10]. Hardware and software methods were used to protect the devices against SEUs.…”

“…However, a single circular cross-section tunnel is built for the x-ray free electron laser (X-FEL), therefore most of electronic devices used to control the machine will be placed in the same vault as the main beam pipe [1,2]. Thus, devices will be exposed to bremsstrahlung gamma radiation and photoneutrons produced during the operation of a linear accelerator [3,4].…”

Oscilador controlado Por tensão com estrutura em anel, com critérios de confiabilidade aos efeitos da radiação

“…Essas partículas são de energia muito menor do que a original, portanto, danos ionizantes conduzidos por nêutrons são relativamente pequenos. Por exemplo, dispositivos podem ser degradados a densidades de energia muito elevadas de nêutrons na gama de 10 15 nêutrons/cm 2 [76]. Quando uma partícula de radiação de alta energia atinge esta estrutura, pode desalojar ou deslocar o núcleo do átomo no ponto onde houve colisão.…”