Experimental optimisation of a moderated 252Cf source for land mine detection

A moderated 252Cf source to be used for the detection of buried land mines has been experimentally characterised. The moderating structure was obtained by using an inner sphere of Pb embedded in a high-density polyethylene (HDPe) brick assembly. The number of capture events in a Cd sample placed outside the structure was used, by varying the dimensions of the brick assembly, to determine the best moderator geometry. Furthermore, the detection of land mines by neutron capture reaction on nitrogen nuclei contained in the explosive was simulated by in field measurements placing the Cd sample at different depths in the soil. The obtained results are compared with predictions from Monte Carlo calculations.