Passive standoff detection of radiological products in the thermal infrared region

Abstract

An investigation is made into the possibility of applying the passive standoff detection technique to the identification of radiological and related products. This work is based on laboratory measurements of the diffuse reflectance from a number of radiological or related products, including U 3 O 8 , ThO 2 , CsI, SrO, I 2 O 5 and La 2 O 3 . With the use of these measured reflectances, simulations of the nadir radiances with the various types of surface reflectances were carried out with the MODTRAN4 transmission model. The simulations were performed for two types of scenarios; at an altitude of 1 m above the ground for the purpose of simulating the passive detection of nuclear products with a hand-held instrument, and at an altitude of 1 km to emulate the conditions of a passive sensor carried aloft in an aircraft. The results of the simulations under idealized conditions show that there is a good potential for being able to measure radiological products or related materials by passive standoff detection using Fourier-transform infrared radiometric techniques.

Recent results from the standoff detection of radiological materials by passive FTIR radiometry

“…The spectrum is consistent with the differential radiance spectrum simulated for SrO in a previous paper. 9 The arrows denote similarities in the SrO features of the measured and reference spectra. The differential radiance spectrum measured in the absence of the SrO powder is also shown to demonstrate the stability of the measurement baseline.…”

“…8,9 In this paper, we extend this analysis to include other important materials and present some preliminary passive standoff measurements. This study concerns the measurements of diffuse reflectance from a number of radiological or related products, including the oxides of uranium (UO 2 , UO 3 ), the oxides of cobalt (CoO and Co 2 O 3 ) and iridium oxide (IrO 2 ).…”