In addition, an evaluation of the sensors responsivity to the effects of two optically reflecting materials was studied.2.?Materials and ExperimentThe sensor consists of a 550 mm PMMA type FDPF 4001 EH optical fiber, having a fiber/jacket diameter of 1 mm/2.2 mm, and a polyethylene jacket. The jacket was striped at both ends over a length of 10 mm. A SMA 950 connector was mounted at one end, whereas the sensor tip is located at the other end. The sensor investigated in the present study embeds the Gd2O2S:Tb phosphor [14]. The sensor was manufactured by preparing a mixture of phosphorous scintillating material with an epoxy solution produced by Struers (Catcliffe Rotherham, S60 5BL, UK) and known as ��Epofix�� [15]. Six sensors were produced with the same technology.

Samples 55 to 58 were produced using a plastic cylinder type mould of 3 mm internal diameter, while sensors 59 and 60 were developed using a heat shrink type mould of 2 mm internal diameter. Sensors 55, 56, and 59 have the length of 10 mm, while for sensors 57, 58, and 60 the length is 5 mm. The diameter of sensors 55 to 58 is 3 mm, and the diameter of sensors 59 and 60 is 2 mm. All sample fiber cores were prepared with the same metallurgical sanding and polishing methods [15]. The sensors’ performances and quality were tested by combining X-ray fluorescence, radioluminescence, and X-ray imaging tests carried out on the sensor tip.

The purpose of the reported investigations was to evaluate six different sensors, prepared with the same technology, in order: to identify the active constituents concentration in the sensor tip; to evaluate the spatial distribution of the phosphor material constituents (Gd and Tb) in each sensor tip; to assess the concentricity of the sensor tip against the optical fiber core. The reproducibility of the sensors response to X-ray was also estimated, along with the spatial distribution of this responsivity along the tip length. The sensors response to various operating conditions of the X-ray source was also assessed. In addition, the effect produced by two reflecting materials covering the sensor Carfilzomib tip on its response is reported.The set-up for X-ray fluorescence investigations consist of a miniature AMPTEK Inc. X-ray tube system (AMPTEK INC., Bedford, MA, USA), operating with an Ag target [16]. The generated X-ray beam was focused, at about 2 mm spot diameter, on the optical fiber sensor tip. The fluorescence signal was picked up by a Silicon Drift Detector [17]. The entire system is controlled via USB connection by the Mini-X Control Software, making possible to set the voltage and current of the source, and the XRF-FP Quantitative Analysis Software for data analysis.