Abstract
A small-sized dual-hemisphere irradiation facility designed and constructed for using Am-Be isotopic neutron source to study and characterize the neutron field around sample irradiation position for obtaining maximum thermal neutron flux. The foil activation method based on 115In and 197Au was used for monitoring the thermal neutron flux. For field characterization, several combinations of moderation media have been tested (air, sand and water) aiming at the identification of the best combinational setups for sample irradiations using thermal neutrons. To account for epithermal contribution, reaction rates and flux calculations were corrected using tabulated values of Westcott g-factors and resonance integrals for these media. The optimal position for sample irradiation using thermal neutron for both water-water and water-sand setups, inside the irradiation channel, was found at about 6.9 to 10.9 cm from the center of the neutron source.
Highlights
The neutron activation analysis (NAA) method is considered one of the most famous methods to investigate elements in a variety of sample matrices
For this purpose a previously described small-sized neutron irradiator prototype based on a 5 Ci (1.85×1011Bq) Am-Be isotopic neutron source was prepared [1]
Water-Sand Setup In this setup we studied the effect of introducing dense media in the lower hemisphere on the neutron field around the irradiation position being in water
Summary
The neutron activation analysis (NAA) method is considered one of the most famous methods to investigate elements in a variety of sample matrices. In the NAA the sample to be analyzed is exposed to a thermal neutron flux; the induced activity of the sample is measured using absolute or comparative method. The use of the neutron irradiator presents the advantage of supplying a stable neutron flux over a long period [2,3,4], eliminating the need for using expensive neutron producing devices such as reactors or accelerators. This way makes the analyzing process became agile, practical and economic. This work presents the optimization of the neutron irradiator for thermal and epithermal neutron production using several combinations of moderating media
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