Numerical evaluation of a landmine detection system based on the neutron back scattering technique

Abstract

This paper describes an anti-personnel landmine detection system, which is based on the neutron back-scattering technique. It consists of a point-like isotopic neutron source (252Cf, 2,31 × 107 n/s), eight BF3 detectors and a neutron moderating and shielding block made from borated paraffin (3 wt%). It was modeled and tested by carrying out Monte Carlo calculations (MCNP-4C2 Code). The tests were performed in some troublesome conditions which include long burial depths for a landmine, higher humidity levels in the formation and existence of some plastics-like substances in the scanning area near a mine. Use of the neutron moderator behind the BF3 detectors increased the counting statistics and improved the S/N ratio. The system could detect a small cylindrical land mine (<300 g) until a burial depth of 15 cm in limestone and also worked well in distinguishing trinitrotoluene (TNT) from the other nearby substances. However, the presence of moisture in limestone in the level of 5% limited its applicability. Scanning speed of the system was calculated as 9.6 m2/min on an even land surface. The calculations revealed that it would be worthwhile to construct and test such a simple and fast practical system for detecting nonmetallic land mines in a laboratory environment. Key words: Neutron backscattering, landmine, BF3 detectors, 252Cf, MCNP.