Optical Fibre Dosimetry First Thoughts

Goal Target Measuring dose in a distributed way using optical fibres (“active”) Constraints: – Mixed-Radiation Field (Particle Type & Energy) – Dosimetry to be used for: 1.Electronics, components, sensors 2.Materials – Various dose ranges (see below) and respective rates to be considered – Time profile: can also be “pulsed” Target dose ranges: – Few Gy – few kGy (1) – Few kGy – MGy (2) – And associated

What Possible measurement systems Radiation effects to be considered Link of effect to “Dose” through calibration Dependency on a variety of parameters: – Radition field – Dose rate – Time structure (beam), e.g, pulsed – Annealing – Temperature – Etc.

Ingredients Sensor: fibres – Standard fibres (single, (multi)-mode, …) – Radiation qualified (radiation tolerant) – Radiation hard Measurement options – OTDR (RIA) – Bragg Grating (FBG) – (Raman) -> perhaps useful to compensate for secondary effects – Other? Simulation studies – where is the dose coming from? – Source spectra (particle type & energy) to be sampled Dose as a function of energy/type – Secondary effects: NIEL contribution Isotope production (believed to be minor) – How representative are the CHARM fields TID wise Fibre types – CERN types – Fraunhofer – Belgium company for grating

Ingredients Equipment (some available at FINT?) – Laser system – Receivers – OTDR – DAQ – Etc,… Calibration – Different types of fibres (based on selection through literature) – Look at different target doses and dose rates (including annealing behaviour) – Compare different fields and effects Solid state physics – What’s actually happening in the fibre (based on our findings through measurements and modelling) – Some knowledge through literature – Getting in contact with other institutes/researchers on this subject

Who Elisa – CERN optical fibre expert and link person to EN/EL (cabling, fibre installations) – Experience on radiation effects on fibres used at CERN – Support for CHARM installation Jochen – Optical fibre and respective radiation induced effects – available literature and first system tests – Fraunhofer link person (tests, etc.) Markus – CERN Radiation Environment – FLUKA Monte-Carlo code – CHARM facility Julien, Michael – CHARM implementation Ruben, Adam – FLUKA Calculations (two-step + CHARM spectra) Joao, Giovanni, Marco – CERN radiation inventory (levels, locations)

Facilities Fraunhofer – Gamma facility (Co-60) with various dose ranges and rates [TID] – Neutron irradiator [NIEL] – “Passive” irradiation facility (BGS) to reach very high doses [TID] – Access option to Jülich – Proton Beam [TID + NIEL] PSI – CERN has a special contract for beam-time (likely not available as from late 2014) CERN – Mixed beam facility – Accelerator locations Other – CEA reactor: gamma + neutrons [TID + NIEL]

Important First Steps Collecting of information (literature study) – Fibre/Dose qualifications and models – CERN Radiation environment Monte-Carlo studies (aiming to understand the radiation field) CHARM preparations Measurement preparations – how to measure where – Sample preparations and constraints

Time-Line Literature study and information collection [1-2 months] Practical things: CHARM test preparation (layout), etc. [1-2 months] Study of CERN mixed-field radiation environment and preliminary Monte-Carlo simulation studies aiming to determine main dose contributions and serving as possible input for later solid-state physics analysis models [2-4 months] Selection of fibre candidates (in collaboration with FINT) and pre-calibration measurements [3-5 months] Characterization study – Study of radiation induced effects for material candidates intended to be used for dosimetric systems including respective sensitivity analysis [4-8 months] – Radiation test campaigns at mono-energetic radiation test facilities (gammas, protons, neutrons) [4-12 months] – Quantification of related challenges (linearity, influence of particle/energy field, dose rate dependencies, possible issues of duty cycles, pulsed environments, interruptions, etc.) [4-18 months] Selection of most promising candidate(s) for further implementation study and first tests in mixed radiation environments (CHARM, PSI, CEA, etc.)[6-12 months] Solid-state physics analysis in order to deepen the understanding and usage of the observed effects and calibration parameters [8-14 months] Analysis and feasibility study of a respective possible industrial application (e.g, using “optical time-domain reflectometers (OTDR)” or other solutions, e.g, see [1, 2] ) [8-18 months]

Knowledge Optical fibres in all its facets Measurement systems CERN Radiation Environment FLUKA Basics Solid state physics (based on other work)

Other Ideas Boron doping -> to be used for thermal neutrons

CHARM – A New Radiation Test Facility RadSol, Paris, June 27 th -28 th GeV/c protons 12 CHARM: Test Positions 4x40 cm movable shielding

CHARM – A New Radiation Test Facility RadSol, Paris, June 27 th -28 th CHARM: Varying Radiation Field Lateral Positions Longitudin. D+H Full racks, crates, set of cards, components HEH: 10 7 cm -2 h -1 – cm -2 h -1, TID: 10mGyh -1 – 10Gyh -1 HEH: 10 8 cm -2 h -1 – cm -2 h -1 TID: 0.1Gyh -1 – 100Gyh -1 (gradients to be considered) Beam Position target in: HEH: >10 11 cm -2 h -1 TID: >100 Gyh -1 target out: HEH: >10 13 cm -2 h -1 TID: >10 kGyh -1

CHARM – A New Radiation Test Facility RadSol, Paris, June 27 th -28 th Spectra normalized to the 100 MeV flux Different thermal behavior Different high energy (HE) contributions Impact on intermediate energies Shielding Configuration: -> Spectra

CHARM – A New Radiation Test Facility RadSol, Paris, June 27 th -28 th Representative Test Locations Accelerator Tunnels