Monte Carlo simulation of thermal neutron flux of americium-beryllium source used in neutron activation analysis

摘要

The neutron activation analysis is a method of exclusively elemental analysis. Its implementation of irradiates the sample which can be analyzed by a high neutron flux, this method is widely used in developed countries with nuclear reactors or accelerators of particle. The purpose of this study is to develop a prototype to increase the neutron flux such as americium-beryllium and have the opportunity to produce radioisotopes. Americium-beryllium is a mobile source of neutron activity of 20 curie, and gives a thermal neutron flux of (1.8 +/- 0.0007) x 10(6) n/cm(2) s when using water as moderator, when using the paraffin, the thermal neutron flux increases to (2.2 +/- 0.0008) x 10(6) n/cm(2) s, in the case of adding two solid beryllium barriers, the distance between them is 24 cm, parallel and symmetrical about the source, the thermal flux is increased to (2.5 +/- 0.0008) x 10(6) n/cm(2) s and in the case of multi-source (6 sources), with-out barriers, increases to (1.17 +/- 0.0008) x 10(7) n/cm(2) s with a rate of increase equal to 4.3 and with the both barriers flux increased to (1.37 +/- 0.0008) x 10(7) n/cm(2) s.