DEVELOPMENT OF REAL TIME MEASUREMENT SYSTEM WITH HIGH POSITION RESOLUTION FOR NEUTRON FLUX DISTRIBUTION USING OPTICAL FIBER

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A NEW METHOD TO MEASURE NEUTRON FLUX AND GAMMA-RAY INTENSITY DISTRIBUTIONS IN VERY NARROW SPACE HAS BEEN DEVELOPED.IN THIS METHOD.THE TIP OF AN OPTICAL FIBER IS PAINTED WITH A MIXTURE OF ZnS (Ag) SCINTILLATOR,NEUTRON CONVERTOR (LI-6 OR U-235 FOR THERMAL NEUTRONS AND EPTTHERMAL NEUTRONS.AND TH-232 FOR FAST NEUTRONS) AND ADHESIVE PASTE.THE DETECTOR IS MOVED WITH ACONSTANT SPEED OR INTERMITTENTLY BY A FIBER DRIVER CONTROLLED WITH A PERSONAL COMPUTER.THE SUBURACTION OF A PART OF THE DISTRIBUTIONOBTAINED WITH Th-232 FORM THAT OBTAINED WITH U-235 GAVE THE DISTRIBUTION OF THERMAL AND EPITHERMAL NEUTRON DISTRIBUTION.FOR GAMMA-RAY MEASURMENT,THE TIP IS COVERED WITH ONLY ZnS (Ag) OR CsI (TI) SCINTILLATOR.THE LATTER SCINTILLATOR HAS HIGHER DETECTION EFFICIENCY FOR GAMMARAYS WITH ENERGY BETWEEN 35-300keV COMPARED WITH ZnA (Ag). TWO DIFFERENT DISTRIBUTIONS GIVE THE INFORMATION ON THE ENERGY DISTRIBUTION OF GAMMMA-RAYS