Investigation of the optimal material type and dimension for spallation targets using simulation methods

Accelerator-driven systems are extensivelydeveloped to generate neutron sources for research,industrial and medical plans. Different heavy elements areutilized as spallation targets to produce spallation neutrons.Computational methods are efficiently utilized to simulateneutronic behavior of a spallation target. MCNPX 2.6.0 isused as a powerful code based on Monte Carlo stochastictechniques for spallation process computation. This codehas the ability to transport different particles using differentphysical models. In this paper, MCNPX has been utilizedto calculate the leaked neutron yield from Pb, LBE, W, Ta,Hg, U, Th, Sn and Cu cylindrical heavy targets. Effects ofthe target thickness and diameter on neutron yield valuehave been investigated via the thickness and diametervariations between 5–30 and 5–20 cm, respectively. Proton-induced radionuclide production into the targets as wellas leaked neutron spectra from the targets has been calculatedfor the targets of an optimum determined dimension.1 GeV proton particle has been selected to inducespallation process inside the targets. 2 mm spatial FWHMdistribution has been considered for the 1 mA proton beam.Uranium target produced the highest leaked neutron yieldwith a 1.32–3.7 factor overweigh the others. Dimension of15 x 60 cm is suggested for all the cylindrical studiedspallation targets. Th target experienced the highest alphaemitterradionuclide production while lighter elementssuch as Cu and Sn bore the lowest radio-toxicity. LBEliquid spallation target competes with the investigated solidtargets in neutronic point of view while has surpass thanvolatile liquid Hg target.