1. 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

2. 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…
, 24th MCWG meeting

3. 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
, 24th MCWG meeting

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

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

6. 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.
, 24th MCWG meeting

7. 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.
, 24th MCWG meeting

8. Optical time domain reflectometry
Pulses of light are injected into the optical fiber
The back-scattered light is detected.
5ns
1m 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
, 24th MCWG meeting

9. Optical time domain reflectometry
Pulses of light are injected into the optical fiber
The back-scattered light is detected.
5ns
1m 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
, 24th MCWG meeting

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

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

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

13. DOFRS in PS-Booster: Current Status
Basic equipments:
Optical fiber cables (the same ones already installed in CHARM) – produced and available
OTDR FTB500 – available (need of a software update, 2+ weeks needed)
, 24th MCWG meeting

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

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

16. DOFRS in PS-Booster: Current Status
Rack installation – starting on February the 13th
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)
, 24th MCWG meeting

17. 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
, 24th MCWG meeting
2017, January 17th

18. DOFRS in PS-Booster: Current Status
Development of the LabView 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
, 24th MCWG meeting

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

20. 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)
, 24th MCWG meeting

21. 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 aRaman-based Distributed Temperature Sensor
, 24th MCWG meeting

22. Thank you for you attention