UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2013 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
Evaluation of an optical fiber sensor response under X-ray exposure


Authors:
Ion Vâţă (1), Dan Sporea (2), Laura Mihai (2), Denis McCarthy (3), Sinead O’Keeffe (3), Elfed Lewis (3)


Affiliation:
1. “Horia Hulubei” National Institute of Physics and Nuclear Engineering

2. National Institute for Laser, Plasma and Radiation Physics, Laser Metrology and Standardization Laboratory

3. Optical Fiber Sensors Research Centre, University of Limerick, Ireland


E-mail
dan.sporea@inflpr.ro


Keywords:
extrinsic optical fiber sensor, radioluminescence, X-ray detection, X-ray fluorescence


Abstract:
In this paper, we report the characterization of a novel extrinsic optical fiber sensor for radiation detection performed in the frame of the bilateral collaboration existing between the National Institute for Laser, Plasma and Radiation Physics in Bucharest and the University of Limerick. The optical fiber radiation sensor developed at University of Limerick consists of a radiation sensitive tip, based on a scintillating material, mounted at the end of a plastic optical fiber after the outer jacket of the fiber was removed. Various commercial available phosphors were employed to manufacture the sensitive tip. When exposed to X-rays, light is emitted, which is coupled through the plastic optical fiber to a detection device: either a scientific grade optical spectrometer for spectral analysis, or to a multi-pixel photon counting module for events count. An Amptek miniature X-ray source with silver target was used for the excitation of the scintillating materials, while an Amptek Silicon Drift Detectors (SDD) completes the set up for X-ray fluorescence measurements. Five extrinsic optical fiber sensors were analyzed both for the fluorescence response over the sensor length and for their optical responsivity. These investigations made possible the comparative evaluation of the two technologies designed for the development of the sensors. The operation conditions for the X-ray source were: the high voltage potential U was in the range 15-40 kV and the current I in the range 5-100 µA with an estimated spot diameter of 1.0 mm. The Romanian authors acknowledge that their contribution to the work was supported by the grant 8/2012 of Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii (UEFISCDI), project “Sensor Systems for Secure Operation of Critical Installations - SOCI”. The investigation was done as part of the COST Action TD1001 “Novel and Reliable Optical Fibre Sensor Systems for Future Security and Safety Applications (OFSeSa)”. The Irish authors wish to acknowledge the support of the European Commission under the 7th Framework Programme through the ‘Marie Curie Re-integration’ action of the ‘Peoples’ Programme (PERG04-2008-239207).