Donald Eric Hornback

Multiagency Urban Search Experiment Detector and Algorithm Test Bed

In order to provide benchmark data sets for radiation detector and algorithm development, a particle transport test bed has been created using experimental data as model input and validation. A detailed radiation measurement campaign at the Combined Arms Collective Training Facility in Fort Indiantown Gap, PA (FTIG), USA, provides sample background radiation levels for a variety of materials present at the site (including cinder block, gravel, asphalt, and soil) using long dwell high-purity germanium (HPGe) measurements. In addition, detailed light detection and ranging data and ground-truth measurements inform model geometry. This paper describes the collected data and the application of these data to create background and injected source synthetic data for an arbitrary gamma-ray detection system using particle transport model detector response calculations and statistical sampling. In the methodology presented here, HPGe measurements inform model source terms while detector response calculations are validated via long dwell measurements using 2”

Motion estimation accuracy for visible-light/gamma-ray imaging fusion for portable portal monitoring

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Systematic Assessment of Neutron and Gamma Backgrounds Relevant to Operational Modeling and Detection Technology Implementation

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Design of Dual-Road Transportable Portal Monitoring System for Visible Light and Gamma-Ray Imaging

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Three-Dimensional Event Localization in Bulk Scintillator Crystals Using Optical Coded Apertures

” NaI(Tl) detectors at a variety of measurement points. A collection of responses, along with sampling methods and interpolation, can be used to create data sets to gauge radiation detector and algorithm (including detection, identification, and localization) performance under a variety of scenarios. Data collected at the FTIG site are available for query, filtering, visualization, and download at muse.lbl.gov.

Accuracy of a stereo vision system for portable roadside portal monitoring

The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Portable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest. We have constructed a prototype, rapid-deployment portal gamma-ray imaging portal monitor that uses machine vision and gamma-ray imaging to monitor multiple lanes of traffic. Vehicles are detected and tracked by using point detection and optical flow methods as implemented in the OpenCV software library. Points are clustered together but imperfections in the detected points and tracks cause errors in the accuracy of the vehicle position estimates. The resulting errors cause a blurring effect in the gamma image of the vehicle. To minimize these errors, we have compared a variety of motion estimation techniques including an estimate using the median of the clustered points, a best-track filtering algorithm, and a constant velocity motion estimation model. The accuracy of these methods are contrasted and compared to a manually verified ground-truth measurement by quantifying the rootmean- square differences in the times the vehicles cross the gamma-ray image pixel boundaries compared with a groundtruth manual measurement.

Ultra-short-period WC/SiC multilayer coatings for x-ray applications

This report summarizes the findings of a two year effort to systematically assess neutron and gamma backgrounds relevant to operational modeling and detection technology implementation. The first year effort focused on reviewing the origins of background sources and their impact on measured rates in operational scenarios of interest. The second year has focused on the assessment of detector and algorithm performance as they pertain to operational requirements against the various background sources and background levels.

Performance of the Roadside Tracker Portal-Less Portal Monitor

The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they enter and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third alignment camera for motion compensation and are mounted on a 50 deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.

Autonomous Radiation Monitoring of Small Vessels

Scintillator-based detectors are among the most commonly used methods for detecting ionizing radiation. Scintillators provide a reliable, cost-effective, and simple way to make large-volume detectors. Furthermore, localizing the position of the interactions in three dimensions within the crystals is useful to a wide array of fields. The most straightforward way of doing this is to pair the crystal with a position-sensitive phototransducer (PT). This allows for measurement of the shape of the light spot at the PT plane. Using this information, various methods exist to localize the gamma-ray interaction in the crystal; however, the position resolution worsens the farther the event occurs from the PT plane. To improve on the localization ability, this work uses an optical coded-aperture shadow mask between the crystal and the PT. The recorded detector response is used in reconstructing the event over the entire depth of the crystal, and the “sharpest” reconstructed image gives an events depth. The lateral position is given from the standard coded-aperture image reconstruction. Experimental results obtained by emulating a 30-mm-thick crystal using a thin 1-mm-thick NaI(Tl) crystal and different amounts of light pipe between the crystal and the PT plane achieved ~1 to 2-mm resolution in all three dimensions throughout most of the 30-mm-thick crystal.

Modeling Urban Scenarios & Experiments: Fort Indiantown Gap Data Collections Summary and Analysis

Increasing concern over the smuggling of fissile material has prompted recent interest in constructing portable, rapidly deployable portal monitors to detect gamma radiation in passing vehicles. In this paper, we introduce a stereo system for precise, real-time, roadside tracking of vehicles in multi-lane roadways. The stereo system reports 3-D vehicle tracks to a gamma imager, which uses the track information to compensate for vehicle motion and produce detectable gamma peaks. We first describe the algorithmic components of the system, including calibration, camera motion correction, point tracking, stereo correspondence, and vehicle clustering. We also describe the physical system configuration. We then report results from tracking two different vehicles at speeds ranging from 5 to 20 MPH. We report on the accuracy of the system, where we observed a worst-case tracking error of 31 cm and an average tracking error of 9 cm in the direction of motion from a viewing distance of approximately 15 m.