Distributed Optical Fibre Radiation and Temperature Sensing at

Distributed Optical Fibre Radiation and Temperature Sensing at High Energy Accelerators and Experiments Update on installation of DOFRS in PS-Booster Diego DI FRANCESCA, EN-EA

Outline • Motivations • Brief description of the working principle of DOFRS • Radiation effects in amorphous silicon dioxide (and silicate optical fibers) • OTDR technology + Radiation Sensitive OF -> DOFRS • Installation in the PS-Booster • Current status • Comparison with other dosimeters? • During 2017… 24. 01. 2017 , 24 th MCWG meeting

Motivations • Providing online and distributed measurements of radiation levels in extended radiation facilities, the CERN accelerators chain. • Combining experiments and simulations to get the most accurate dosimetry maps of the machines • Increasing safety • Cost-efficient and easy to implement solution 24. 01. 2017 , 24 th MCWG meeting

Radiation effects in amorphous silicon dioxide D. Griscom, 1985 24. 01. 2017 , 24 th MCWG meeting

Radiation effects in amorphous silicon dioxide D. Griscom, 1985 … 24. 01. 2017 , 24 th MCWG meeting

Radiation effects in silicate Optical Fibers (OFs) • Radiation Induced Attenuation (RIA) Decrease of the light transmission. The appearance of point defects in the silica matrix is responsible for this effect, which is also dependent on the guiding properties of the OF. • Radiation Induced Emission (RIE) It lowers the signal-to-noise ratio of a transmitted signal. It is due to Cherenkov radiation and the luminescence properties of point defects. • Change of refractive index. It is due to point defects as well as densification induced by displacement damages. 24. 01. 2017 , 24 th MCWG meeting

Radiation effects in silicate Optical Fibers (OFs) • Radiation Induced Attenuation (RIA) Decrease of the light transmission. The appearance of point defects in the silica matrix is responsible for this effect, which is also dependent on the guiding properties of the OF. • Radiation Induced Emission (RIE) It lowers the signal-to-noise ratio of a transmitted signal. It is due to the luminescence properties of point defects. • Change of refractive index. It is due to point defects as well as densification induced by displacement damages. 24. 01. 2017 , 24 th MCWG meeting

Optical time domain reflectometry • Pulses of light are injected into the optical fiber • The back-scattered light is detected. 5 ns 1 m pulse of light The position of the original point from which the light was back-scattered can be determined by the return time of flight 24. 01. 2017 , 24 th MCWG meeting

Distributed Optical Fiber Radiation Sensor OTDR Radiation sensitive OF Light Intensity (d. B) Distance (km) Calibration of the OF sensor Dose (Gy) Distance (km) 24. 01. 2017 , 24 th MCWG meeting

Distributed radiation measurement at CHARM Optical attenuation Measurement Dose calculation and comparasion with simulations. Calibration of the specific OF radiation response is needed Adapted from Iacopo’s previous work 24. 01. 2017 , 24 th MCWG meeting

Installation of DOFRS in PS-Booster: Current Status J. P. Saraiva and M. Brugger, “CERN-ACC-NOTE-2015 -0042”, 2015 24. 01. 2017 , 24 th MCWG meeting

DOFRS in PS-Booster: Current Status • Basic equipments: • Optical fiber cables (the same ones already installed in CHARM) – produced and available • OTDR FTB 500 – available (need of a software update, 2+ weeks needed) 24. 01. 2017 , 24 th MCWG meeting

DOFRS in PS-Booster: Current Status • Installation of the support structure for the rack - DONE 24. 01. 2017 , 24 th MCWG meeting

DOFRS in PS-Booster: Current Status • Installation of the cable tray in the injection/extraction zone – before February the 13 th. 24. 01. 2017 , 24 th MCWG meeting

DOFRS in PS-Booster: Current Status • Rack installation – starting on February the 13 th • Installation of the power supplies for the rack – in progress • Installation of the Ethernet outlets for the control of the OF interrogator – scheduled during EYETS (probably in March) 24. 01. 2017 , 24 th MCWG meeting

DOFRS in PS-Booster: Current Status • Installation of the optical fiber duct– immediately after the Rack installation The same two cables (ready) that were installed in CHARM will be blown in the duct after its installation th MCWG meeting 2017, January 24. 01. 2017 , 24 17 th

DOFRS in PS-Booster: Current Status • Development of the Lab. View interface (carried out by Rudy Ferraro, Salvatore Danzeca) – in progress • Implementation of Iacopo’s algorithm for the calculation of the dose – DONE (with minor details to be added) • Control of the interrogator unit form remote – DONE • Logging of the data on Timber – almost completed • Update of optical fiber sensor calibration – in progress After the installation of the Ethernet outlets we will test the whole system and perform preliminary reference measurements 24. 01. 2017 , 24 th MCWG meeting

DOFRS in PS-Booster: expected radiation doses …. Average dose Gy/y Total expected losses in d. B Raw data 300 150 W/o 1 hotspot 80 45 W/o 2 hotspots 45 23 24. 01. 2017 , 24 th MCWG meeting Data extracted from HLD_PSB 2014/2015

DOFRS in PS-Booster: comparison with other dosimeters Possibility to place some dosimeters (e. g. one every ten meters) close to the Optical Fiber Sensor? Motivations: • double-check of the dose at specific locations • exact registration of the circular cartography (OTDR trace) with respect to the tunnel (spatial configuration) 24. 01. 2017 , 24 th MCWG meeting

During 2017… • PS-Booster measurement campaign ! • Procurement of a new OTDR, to be tested in parallel in the PSB. • Procurement of a new set of radiation sensitive OF and development of a second generation cable (radiation response characterization), to be installed in PSB as soon as possible. • … and also temperature measurement in the PS-booster with a. Raman-based Distributed Temperature Sensor 24. 01. 2017 , 24 th MCWG meeting

Thank you for you attention diego. di. francesca@cern. ch