Three different prototypes of a standoff trace chemical detection system were developed under the IARPA SILMARILS Program in order to advance the technological readiness of this class of sensor. Two of the prototypes utilize a cryo-cooled mercury-cadmium telluride (MCT) camera to achieve high performance capability. The third prototype utilizes a low-cost microbolometer camera and is targeted for applications that require small size and low cost. Applications include vehicle and person borne suicide bombers, airport screening, package screening and customs screening. In this talk, we will discuss the design and performance of all three prototypes.

When developing technologies for military or civilian emergency response, it is critical to understand the target audience, their operational environment, and the use case. Understanding the critical factors that affect a product’s use in the field is critical BEFORE product design can begin and will give a product its best chance at transition. First, consider the operational environment. Second, understand what the data from the sensor will be used for, how fast the data is needed, and how it will be accessed. Third, determine the logistics support available to the operator as this will drive size, weight, and battery requirements. Finally, focus on technologies providing more capability than just the high risk, low frequency targets.

We have measured the sublimation rate of trace quantities of explosives materials as a function of temperature, airflow, inter particle distance, and humidity. In parallel, we have developed a computational model based on Monte Carlo simulation and molecular dynamics to predict sublimation behavior. Together these allow us to predict the persistence of arbitrary particle ensembles provided that certain physical properties such as vapor pressure are known. This data can be used to inform those developing vapor or particle based sensing technologies.

We have investigated the characteristics of particulates found in fingerprint deposition using a surrogate finger and a custom mechanical testbed with in situ microscopy, describing the residue for several explosives materials as a function of applied force and print number. We attempt to account for the presence of oils naturally found on human fingers using a surrogate material and quantify how it affects the particulate residue. The amounts deposited, their spatial distribution and particle sizes are of direct interest to optical-based detection techniques being developed for non-contact or standoff detection of explosives.

This presentation will summarize the prior DARPA SIGMA and current SIGMA+ programs, and provide a review of the chemical, biological and explosive sensing modalities being developed through SIGMA+.

The stand-off, range-resolved detection of hydrogen production rates is a valuable mechanism for the long-term condition monitoring of packages containing intermediate-level nuclear materials. To exploit this effect we have developed a long-range optical sensor system which uses Raman detection of hydrogen. Our need for operation over extended ranges (up to 100m) results in very low Raman signals. We therefore use time-correlated (with respect to the outgoing excitation laser pulse) and spectrally-resolved single-photon detection to ascertain molecular species, position and concentration as revealed by photon energy, arrival time and number, respectively.

The dual requirement for high spatial and substance specificity makes stand-off in-theatre biological detection of surface biological contaminants extremely challenging. We will describe a novel combined fluorescence multispectral imaging (MSI) and stand-off Raman approach which are united through their use of deep-UV (sub-250 nm excitation. This allows high-confidence location and classification of candidate contamination sites over the camera field of view, and subsequent resonance-Raman classification of these identified sites. Stand-off Raman is enabled through the use of a novel, extremely high-throughput Spatial Heterodyne spectrometer. The viability of this approach is confirmed through its use on application relevant biological simulant samples.

Recent work with B. anthracis Delta Sterne spores demonstrated that Raman spectroscopy could be used to discriminate between viable and gamma deactivated spores and provided initial insight into the probable source of discrimination found in the spores. From this previous work, we believe through Raman spectral analyses of viable and deactivated spore samples, significant changes in spectral response can be resolved and ascribed to classes of biomolecules affected by the deactivation processes. We expanded upon this study to include four different Bacillus spores (B. anthracis, B. megaterium, B. thuringiensis, and B. atrophaeus) and probe de-activation techniques to include gamma radiation UV radiation, chemical, and thermal methodologies. We used sequential Raman imaging scanning electron (RISE) microscopy to determine chemical (Raman spectral information) and physical (SEM imaging) variance between viable and deactivated spore samples. Additional use of machine learning algorithms to

This presentation presents an overview of the NATO Science and Technology Office structure along with a CBRNE perspective highlighting current and future challenges. Current specific Sensor & Electronic Technology panel activities will be discussed addressing optical detection efforts, including surface-enhanced Raman scattering for military relevant materials, inkjet deposition technologies for testing and evaluation of sensors, and ground contamination and avoidance of deposited hazards.

We measured Raman spectra (RS) of ambient aerosols semi-continuously, to determine the compositions of individual aerosol particles at 15-20 minute time-resolution. The automated aerosol-Raman spectrometer (ARS) we use is Battelle’s (Columbus, OH) REBS. Many RS exhibit a broad luminescence, which can vary from one replicate to another because of photobleaching, thermal changes in crystal structure, or other phenomena. Materials consistent with the measured RS include DG carbon, organic carbon, and minerals such as calcite and quartz. We illustrate differences in the compositions consistent with the RS observed at a semi-urban site in Maryland and a rural site in New Mexico.