Distributed Optical Fiber Radiation Sensing at CERN

Gaetano Li Vecchi (1, 2) , Diego Di Francesca (1) , R. Ferraro (1) , Salvatore Danzeca (1) , O. Stein (1) , Yacine Kadi (1) , Markus Brugger (1) , Sylvain Girard (2)

1 CERN - European Organization for Nuclear Research
2 LHC - Laboratoire Hubert Curien

CERN’s accelerator tunnels are very complex mixed field radiation environments, in which many electronic components and systems are installed. The radiation generated by the circulating beam degrades all electronic equipment and impacts directly its lifetime. In the worst case, it may also cause failures that contribute to increase the machine downtime periods. Consequently, both active and passive dosimetry technologies are used to monitor the radiation levels. These point radiation sensors are installed in thousands of specific locations in the machine tunnels, and the nearby caverns, in order to provide either online or post-irradiation radiation dose measurements. In this contribution, we present a new radiation monitoring technology implemented at CERN called Distributed Optical Fiber Radiation Sensor (DOFRS). The first operational prototype of this system was installed in 2017 in the Proton Synchrotron Booster (PSB), the first and smallest circular accelerator of the injection chain of LHC. The most interesting capability of the DOFRS, with respect to other currently installed dosimetry systems, is to provide one dimensional maps of radiation dose levels all along the sensing Optical Fiber (OF). Such characteristic makes it very well-adapted for radiation detection and dosimetry in large facilities and accelerators. In particular, it allows the online monitoring of the cumulated radiation dose over hundreds of meters with a spatial resolution down to one meter. By combining these measurements with simulation studies, it is also possible to draw conclusions on the radiation dose levels at locations closer to the beam line. Below, we report the results and performances of the DOFRS in the PSB after its first year of operation. The measurements are compared to several point passive dosimeters that were installed in regions of interest in close proximity to the OF sensor. Furthermore, the system under implementation at CERN provide distributed temperature measurement capabilities specifically adapted for radiation environment

Domaines: Sciences de l'ingénieur [physics]

Gaetano Li Vecchi, Diego Di Francesca, R. Ferraro, Salvatore Danzeca, O. Stein, et al.. Distributed Optical Fiber Radiation Sensing at CERN. 9th International Particle Accelerator Conference (IPAC 2018), Apr 2018, Vancouver, Canada. pp.WEPAF083, ⟨10.18429/JACoW-IPAC2018-WEPAF083⟩. ⟨ujm-01964698⟩