STUDY OF NEUTRON SCATTERING CONTRIBUTION ON H_p(10) AND H~*(10) CALIBRATION IN THE BRAZILIAN NATIONAL LOW SCATTERING LABORATORY

摘要

The neutron scattering at the Low Scattering Laboratory of the Brazilian National Neutron Laboratory has been studied using three different methods. The measurements have been done with a traceable standard ~(241)Am-Be from source-to-detector distances of 0.52-3.00 m. The obtained results with the variation distance methods are in agreement. Measurements with a large shadow cone are not worth for larger distances due to overshadowing. As the quantity required in a calibration is the response of the device being calibrated to the scattered neutron component in order to subtract this from the total response, for these purposes, the distance variation method must be used for each device. To quantify absolutely the scattering contribution on the quantity rates of fluence, H_p(10) and H~*(10) in irradiation procedures, a Bonner sphere spectrometer with the shadow cone was employed. The evaluated scattering correction factor value may be employed for a distance of 1.00 m.