Nondestructive detection of hidden chemical compounds with laser Compton-scattering gamma rays

Abstract

A nondestructive assay method for measuring a shielded chemical compound has been proposed. The chemical compound is measured by using a nuclear resonance fluorescence (NRF) measurement technique with an energy tunable laser Compton-scattering (LCS) -ray source. This method has an advantage that hidden materials can be detected through heavy shields such as iron plates of a thickness of several centimeters. A detection of a chemical compound of melamine, C3H6N6, shielded by 15-mm-thick iron and 4-mm-thick lead plates is demonstrated. The NRF -rays of 12C and 14N of the melamine are measured by using the LCS -rays of the energies of up to 5.0 MeV. The observed ratio (12C/14N)exp=0.39±0.12 is consistent with (C/N)melamine=0.5.