The shape of laminated products is a crucial parameter in high-speed and high-volume finishing lines where they must fulfill tight tolerances. Latent defects are detected by flatness rolls (or shapemeter rolls) inserted in the... more
The shape of laminated products is a crucial parameter in high-speed and high-volume finishing lines where they must fulfill tight tolerances. Latent defects are detected by flatness rolls (or shapemeter rolls) inserted in the manufacturing line for online flatness control. A prototype of flatness roll has been developed with high spatial resolution (5 mm) and measurement capability over a thickness range of 0.1–1 mm to evaluate flatness and residual stresses of flat metal strip products manufactured by continuous cold rolling (ultra-thin sheets for packaging and automotive markets). The flatness roll prototype relies on pressure-induced strain sensing on segmented blades using Fiber Bragg Grating technology. Synchronous measurement of the flatness profile across strip width rejects disturbances of strip tension during rolling. We provide a proof-of-concept on pilot lines in both static and dynamic conditions (e.g., roll in rotation and in contact with a strip under tension) and the...
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Research Interests: Physics, Materials Science, Biomedical Engineering, Radiation Therapy, Optical fiber sensors, and 14 moreCrystals, Radiation Effects, Calibration, Silicon Photomultipliers, Optical fiber, Optically Stimulated Luminescence, Dosimetry, Optical Fibers, Optical Filters, Radioluminescence, Fibre Optic Sensors, Dosimeter, Heating Systems, and Photomultiplier Tubes
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ABSTRACT Safety must always prevail in Nuclear Power Plants (NPPs), as shown at Fukushima-Daiichi. So, innovations are clearly needed to strengthen instrumentations, which went inoperative during this nuclear accident as a consequence of... more
ABSTRACT Safety must always prevail in Nuclear Power Plants (NPPs), as shown at Fukushima-Daiichi. So, innovations are clearly needed to strengthen instrumentations, which went inoperative during this nuclear accident as a consequence of power supply losses. Possible improvements concern materials and structures, which may be remotely monitored thanks to Optical Fiber Sensors (OFS). We detail topics involving OFS helpful for monitoring, in nominal conditions as well as during a severe accident. They include distributed sensing (Rayleigh, Raman, Brillouin) for both temperature sensing and structure monitoring as well as H2 concentration and ionizing radiation monitoring. For future plants, Fiber Bragg Grating (FBG) sensors are considered up to high temperature for sodium-cooled fast reactor monitoring. These applications can benefit from fiber advantages: sensor multiplexing, multi-km range, no risk-to-people, no common failure mode with other technologies, remote sensing, and the ability to operate in case of power supply lost in the NPP.
Research Interests: Engineering, Materials Science, Temperature Sensors, Accidents, Nuclear power, and 13 moreOptical fiber sensor, Fukushima, Fiber Bragg gratings, Optical Sensors, Composite structures, Distributed Sensing, Radiation Monitoring, Optical fiber, Nuclear Power Plants, RFID Based Structure Health Monitoring, Ionizing Radiation, Accident Prevention, and Fast Reactors
Accurate measurement of detonation velocity of high explosives enables to improve the manufacturing conditions and to qualify both vulnerability and aging. Chirped Fiber Bragg Gratings are investigated for in situ distributed velocity... more
Accurate measurement of detonation velocity of high explosives enables to improve the manufacturing conditions and to qualify both vulnerability and aging. Chirped Fiber Bragg Gratings are investigated for in situ distributed velocity measurements.
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Research Interests: Materials Science, Biomedical Engineering, Monte Carlo, Brachytherapy, Photonics, and 15 moreMedical Physics, Optical fiber sensors, Crystals, IMRT, Optical fiber sensor, Radiation Effect, Medical Linear Accelerator, Optical fiber, Optically Stimulated Luminescence, Fiber Optic, Dosimetry, Intensity Modulated Radiation Therapy, Optical Fibers, Monte Carlo Method, and linear accelerators
Purpose: This work is aimed at developing a new probe to improve the accuracy of the dose delivery follow up in some Radiotherapy (RT) treatments that involve small fields like Irradiation Modulated RT (IMRT) and/or high dose gradients... more
Purpose: This work is aimed at developing a new probe to improve the accuracy of the dose delivery follow up in some Radiotherapy (RT) treatments that involve small fields like Irradiation Modulated RT (IMRT) and/or high dose gradients like Brachytherapy (BT) where the In Vivo Dosimetry (IVD) still remains challenging. Material and Methods: The OSL/FO (Optically Stimulated Luminescence/Fibre Optics) system designed by CEA LIST is composed of a multichannel reader and OSL OFS (Optical Fibre Sensors) incorporating dosimetric‐grade alumina crystals (Al2O3:C, grown in reducing atmosphere in the presence of carbon). Al2O3 :C crystals exhibit good sensitivity and small fading at room temperature. They are small (0.09 mm3), optically transparent, non‐hygroscopic, chemically inert. The OSL OFS are made of low‐Z materials (polymer, PMMA, alumina). They are electromagnetic‐immune, radiation‐resistant and transparent. The reader unit may deal with up to 15 channels with the use of an optical switch thus leading to an optimised cost‐per‐sensor ratio. During irradiation, part of free electrons promptly recombine and generate a RL (that provides realtime dose estimation) while another portion is kept stored. After irradiation, the crystal is remotely reset by laser light and the OSL is recorded to get the absorbed dose. Results and Conclusion: Within the French INTRADOSE project, the CEA‐LIST is currently developing small dosimetric catheters with the aim of measuring the intracavitary dose distribution, close to organs at risk. This yields the maximal dose and the source‐sensor distance. This device would allow checking that the source of 192Ir moves along the tubes, according to the treatment planning system. Metrological validations will be performed for both BT (prostatic cancer) and IMRT (head and neck cancer) treatments.
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ABSTRACT A multichannel OSL Fibre Optic dosimeter based on Optically Stimulated Luminescence (OSL) of alumina is proposed for on-line In Vivo Dosimetry (IVD) in Radiation Therapy (RT). Two types of dosimetric-grade Al2O3:C crystals are... more
ABSTRACT A multichannel OSL Fibre Optic dosimeter based on Optically Stimulated Luminescence (OSL) of alumina is proposed for on-line In Vivo Dosimetry (IVD) in Radiation Therapy (RT). Two types of dosimetric-grade Al2O3:C crystals are compared and show different behavior according to manufacturing process. Metrological validations have been performed with a Saturne 43 LINAC in reference conditions at CEA LIST LNHB (French Ionizing Radiation Reference Laboratory). The dose response of OSL integrals under photon beam irradiation (6, 12 and 20 MV) show sublinearity behavior modeled by second-order equations and exhibit a small energy dependence (between 0.7% and 1.4%), explained by a modified intermediate cavity model adapted to a LINAC photon spectrum. Preclinical tests at Institut Gustave Roussy (IGR) prove that a proper design for a PMMA build-up cap leads to a low dependence vs photon beam orientation (± 1.5 % and ± 0.9 %) and vs field size in view of surface measurements.
A new kind of instrumentation based on Optical Fiber Bragg grating sensors is proposed for the main relevant monitoring needs in the electric power industry. The challenging metrological properties of these components are presented and... more
A new kind of instrumentation based on Optical Fiber Bragg grating sensors is proposed for the main relevant monitoring needs in the electric power industry. The challenging metrological properties of these components are presented and their good resistance to (gamma) -ray irradiations experimentally proved.
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ABSTRACT Corrosion of reinforced bar (rebar) in concrete structures represents a major issue in civil engineering works, being its detection and evolution a challenge for the applied research. In this work, we present a new methodology to... more
ABSTRACT Corrosion of reinforced bar (rebar) in concrete structures represents a major issue in civil engineering works, being its detection and evolution a challenge for the applied research. In this work, we present a new methodology to corrosion detection in reinforced concrete structures, by combining Fiber Bragg Grating (FBG) sensors with the electrochemical and physical properties of rebar in a simplified assembly. Tests in electrolytic solutions and concrete were performed for pitting and general corrosion. The proposed Structural Health Monitoring (SHM) methodology constitutes a direct corrosion measurement potentially useful to implement or improve Condition-Based Maintenance (CBM) program for civil engineering concrete structures.
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SUMMARY A new manufacturing process for advanced Fiber Bragg Gratings which uses phase plates is described. Its high versatility allows to achieve many type of filters in optical fibers (phase-shifted, apodised, Fabry-Perot).
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This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500))... more
This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve.
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... RM Percival. iR Perry. RG Smart, PJSuni and AC. ... MJ Weber In: WM Yen and PM Selzer, Editors, Laser Spectroscopy of Solids, Springer, New York (1981), p. 189. DC Hanna, RM Percival, IRPerry, RG Smart, PJ Suni and AC Tropper, J. Mod.... more
... RM Percival. iR Perry. RG Smart, PJSuni and AC. ... MJ Weber In: WM Yen and PM Selzer, Editors, Laser Spectroscopy of Solids, Springer, New York (1981), p. 189. DC Hanna, RM Percival, IRPerry, RG Smart, PJ Suni and AC Tropper, J. Mod. Optics 37 (1990), p. 517. ...
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The Codofer Project (2007–2009), led under the ANR-TECSAN Call, was coordinated by CEA LIST, in partnership with IGR and the Fimel company. The aim of the project was to design and test both metrologically and in clinical conditions OSL... more
The Codofer Project (2007–2009), led under the ANR-TECSAN Call, was coordinated by CEA LIST, in partnership with IGR and the Fimel company. The aim of the project was to design and test both metrologically and in clinical conditions OSL optical fiber sensors dedicated to in vivo dosimetry during external beam radiation therapy treatment with high-energy electrons. This study, combined with the results of clinical tests obtained within the European Project Maestro, has demonstrated the advantages of OSL/FO dosimetry for providing quality assurance of treatments. However, the French market for dosimetry has greatly changed as a result of the rules edicted by the French government in 2007. The OSL/FO product is now targeted for other treatment modalities lacking suitable dosimeters (ANR-INTRADOSE Project [2009–2011]).