Abstract
Neutron generators are now used in various fields. They produce only fast neutrons; D-D neutron generator produces 2.45 MeV neutrons and D-T produces 14.1 MeV neutrons. In order to optimize shielding-collimator parameters to achieve higher neutron flux at the investigated sample (The signal) with lower neutron and gamma rays flux at the area of the detectors, design iterations are widely used. This work was applied to ROMASHA setup, TANGRA project, FLNP, Joint Institute for Nuclear Research. The studied parameters were; (1) shielding-collimator material, (2) Distance between the shielding-collimator assembly first plate and center of the neutron beam, and (3) thickness of collimator sheets. MCNP5 was used to simulate ROMASHA setup after it was validated on the experimental results of irradiation of Carbon-12 sample for one hour to detect its 4.44 MeV characteristic gamma line. The ratio between the signal and total neutron flux that enters each detector was calculated and plotted, concluding that the optimum shielding-collimator assembly is Tungsten of 5 cm thickness for each plate, and a distance of 2.3 cm. Also, the ratio between the signal and total gamma rays flux was calculated and plotted for each detector, leading to the previous conclusion but the distance was 1 cm.
Highlights
Neutron generators are used in various fields and their applications are enormously increasing
Another model was developed based on using the Artificial Neural Networks (ANNs) to predict the MCNP results in order to be used later in generating the data required for the optimization process
In order to simplify the process of analyzing the results, the symmetry mentioned previously was used to compare the different parameters for half the number of channels
Summary
Neutron generators are used in various fields and their applications are enormously increasing. They produce only fast neutrons; the D-D neutron generator produces 2.45 MeV neutrons and the D-T produces 14.1 MeV neutrons. One of the problems of neutron generators is optimization of the parameters of neutron-gamma shielding-collimator assembly [1]. The purpose of the optimization is to reach an acceptable value of the ratio between neutron flux in the investigated sample (the signal) and neutron flux in the area of the detectors (the background) to reach as low as possible gamma rays from inelastic scattering of fast neutrons with the shield. Various simulations and experiments are needed for the design of the shielding-collimator assembly.
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