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Vacaliuc, Bogdan

Publications and source records attributed to Vacaliuc, Bogdan.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Scintillator-based Timepix3 detector for neutron spin-echo techniques using intensity modulation

A scintillator-based Timepix3 (TPX3) detector was developed to resolve the high-frequency modulation of a neutron beam in both spatial and temporal domains, as required for neutron spin-echo experiments. In this system, light from a scintillator is manipulated with an optical lens and is intensified using an image intensifier, making it detectable with the TPX3 chip. Two different scintillators, namely, 6 LiF:ZnS(Ag) and 6 LiI:Eu, were investigated to achieve the high resolution needed for spin-echo modulated small-angle neutron scattering (SEMSANS) and modulation of intensity with zero effort (MIEZE). The methodology for conducting event-mode analysis is described, including the optimization of clustering parameters for both scintillators. The detector with both scintillators was characterized with respect to detection efficiency, spatial resolution, count rate, uniformity, and γ-sensitivity. The 6 LiF:ZnS(Ag) scintillator-based detector achieved a spatial resolution of 200 μm and a count rate capability of 1.1 × 10 5 cps, while the 6 LiI:Eu scintillator-based detector demonstrated a spatial resolution of 250 μm and a count rate capability exceeding 2.9 × 10 5 cps. Furthermore, high-frequency intensity modulations in both spatial and temporal domains were successfully observed, confirming the suitability of this detector for SEMSANS and MIEZE techniques, respectively.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Deployment of ADTimePix3 areaDetector Driver at Neutron and X-ray User Facilities

TimePix3 is a 65k hybrid pixel readout chip with simultaneous Time-of-Arrival (ToA) and Time-over-Threshold (ToT) recording in each pixel*. The chip operates without a trigger signal with a sparse readout where only pixels containing events are read out. The flexible architecture allows 40 MHits/s/cm² readout throughput, using simultaneous readout and acquisition by sharing readout logic with transport logic of superpixel matrix formed using 2x4 structure. The chip ToA records 1.5625 ns time resolution. The X-ray and charged particle events are counted directly. However, indirect neutron counts use 6Li fission in a scintillator matrix, such as ZnS(Ag). The fission space-charge region is limited to 5-9 um. A photon from scintillator material excites a photocathode electron, which is further multiplied in dual-stack MCP. The neutron count event is a cluster of electron events at the chip. We report on the EPICS areaDetector** ADTimePix3 driver that controls Serval*** using json commands. The driver directs data to storage and to a real-time processing pipeline and configures the chip. The time-stamped data are stored in raw .tpx3 file format and passed through a socket where the clustering software identifies individual neutron events. The conventional 2D images are available as images for each exposure frame, and a preview is useful for sample alignment. The areaDetector driver allows integration of time-enhanced capabilities of this detector into SNS beamlines controls and unprecedented time resolution.

Gofron, Kaz↗
DOE OSTI2023

Interactive automated Bragg peak identification with 3D neutron scattering data

Neutron scattering experiments have undergone significant technological development through large area detectors with concurrent enhancements in neutron transport and electronic functionality. Data collected for neutron events include detector pixel location in 3D, time and associated metadata, such as, sample orientation, neutron wavelength, and environmental conditions. RadiaSoft and Oak Ridge National Laboratory personnel are considering single-crystal diffraction data from the TOPAZ instrument. We are leveraging a new method for rapid, interactive analysis of neutron data using NVIDIA’s IndeX 3D volumetric visualization framework. We have implemented machine learning techniques to automatically identify Bragg peaks and separate them from diffuse backgrounds and analyze the crystalline lattice parameters for further analysis. The implementation of automatic peak identification into IndeX allows scientists to visualize and analyze data in real-time. Our methods include a robust comparison with current analysis techniques which show improvement in a variety of aspects. These improvements will be incorporated into IndeX for visualization to allow scientists an interactive tool for crystal analysis.

Kilpatrick, Matthew↗
DOE OSTI2022

Modern Trends in Neutron Scattering Instrument Technologies

This article reviews some current trends that can be observed in the development of neutron scattering instrument technologies. While the number of neutron scattering facilities worldwide and the number of beam days they offer are largely stable, their scientific impact is increasing through improving instrumental capabilities, new and more versatile instruments, and more efficient data collection protocols. Neutron beams are becoming smaller but more intense, and instruments are being designed to utilize more ‘useful’ neutrons in unit time. This article picks and discusses a few recent developments in the areas of integrated source and instrument design, use of computational tools, new detectors, and experiment automation.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Multimodal communication system

A multimodal communication system includes a vehicle controller that controls one or more systems or subsystems of an unmanned vehicle. The communication controller manages communication and logical access to the unmanned vehicle. One or more sensors in communication with the communication controller detects and measures physical properties in proximity to the unmanned vehicle. Transceivers receive the unmanned vehicle commands that are transmitted simultaneously or concurrently and a monotonic generator generates a monotonic object each time the unmanned vehicle's operating state changes. The communication controller executes the first unmanned vehicle command received that has the correct cryptographic hash validating knowledge of the unmanned vehicle's current operating state.

Duncan, Andrew M.↗
DOE OSTI2020

Artificial illumination identification from an unmanned aerial vehicle

Artificial illumination identification within images is a useful tool for many applications. Performing such identification allows for an estimation of the illumination source spectrum, which in turn can be used for additional applications ranging from spectral detection and exploitation to statistics about nighttime light usage. Illumination identification has been performed in laboratory settings but not from an unmanned aerial vehicle (UAV) platform. Here, we test the feasibility of using a UAV and commercial off-the-shelf multispectral imaging sensor to perform such artificial illumination identification through linear discriminant analysis using nighttime UAV images. The results are very promising, showing source classification accuracies of 83.3%, 92.3%, 100%, and 100% for the incandescent, light-emitting diode, high pressure sodium, and metal halide illumination sources, respectively. We show that the information gained from the source identification can be further used to inform additional analysis, such as spectral identification. The high resolution of UAV imaging techniques combined with the knowledge of the illumination source can lead to better exploitation of such nighttime data for many applications.

42 ENGINEERING↗
DOE OSTI2019

ADVANCING THE TRANSPORTATION – SECURITY, TRACKING, AND REPORTING (T-STAR) SYSTEM

The Transportation – Security, Tracking and Reporting (T-STAR) System was developed by NNSA NA-21 Office of Radiological Security (ORS) to provide a transportation security system for use during transport of Category 1 and Category 2 radiological material to provide detection and tracking capability for shipments. While many off the shelf systems provide asset tracking of the conveyance, few offer detection of a breach into the cargo compartment or the removal of cargo from the conveyance. Systems that do offer such capability need to be permanently installed on the conveyance, requiring drilling of holes and running of cables throughout the conveyance itself. This means that dedicated shipping containers or vehicles are required, and this is not sustainable in many countries where ORS is building capacity for the security of radioactive materials in use, storage, and in transport. T-STAR is leveraging various ORNL technologies for improved communications capability and reduced power requirements; the multimode communications module developed by the Unmanned Aerial Systems group and the low power and extensible Authenticatable Container Tracking System (ACTS) tag developed for the US Department of Energy’s Packaging Certification Program provide a small footprint tracking system which can be installed quickly as needed. T-STAR uses a cellular and an Iridium modem to communicate configuration and alert information to a server used to monitor the shipment and incorporates a Z-wave © wireless security system allowing various intrusion detection sensors to be located in the conveyance. The Z-wave sensors are readily available, inexpensive, and power efficient, making them replaceable and low maintenance. The server software be configured as a standalone system installed on a light duty computer hosted by the competent authority, carrier, or response agency, or hosted as part of an Amazon Cloud Server (AWS) accessible via a secure login. The server has two functions, first is to handle messages to/from the T-STAR field unit, second is to host the user interface which can be accessed using a web browser on desktop or mobile device. The user interface implements roles to determine the level of access to shipment information, define geo-fences, and configure notifications. The user interface also supports multiple languages for display as well as notifications by using a simple lookup file which can be modified by the host country to ensure translations are correct and meaningful to responders receiving notifications and alerts. This paper will detail the overarching T-STAR capabilities, architecture and components, and provide insights on how it is deployed, used, and monitored during transportation of radioactive material.

Schultze, Michael↗
DOE OSTI2019

Integration and operation of a sUAS-based multi-modal imaging payload equipped with a novel communication system enabling autonomous platform control

Oak Ridge National Laboratory presents a new UAS-mounted multi-modal imaging payload containing five sensors. We have integrated several distinct commercially available sensors onto a large Class-1 autonomous quadcopter aircraft: a LIDAR (Light Detection and Ranging) scanner, a hyperspectral pushbroom sensor, a multispectral camera, a longwave infrared thermal camera, and an RGB camera. The system integrates our proprietary Multi-modal Autonomous Vehicle Network (MAVNet) and communication system, allowing autonomous control via multiple communication networks. Using one common Global Navigation Satellite System (GNSS) and inertial navigation system (INS/GPS), imagery from all sensors are accurately and precisely geolocated and co-registered.

Duncan, Andrew↗
DOE OSTI2019

MAVNet: Design of a Reliable Beyond Visual Line of Sight Communication System for Unmanned Vehicles

This paper details the design and system components of the Multi-Modal Autonomous Vehicle Network system (MAVNet). MAVNet was designed to provide reliable and redundant command, control and payload data distribution for unmanned vehicles operating beyond visual line of sight. Current industry solutions do not adequately solve key networking challenges, do not support network diversity and fall short of providing desirable next-generation requirements including data fusion from national air space data sources, multi-pilot and multi-agent control. The MAVNet system and the approach taken to solve these issues will be detailed in this paper.

Stinson, Brad J↗
DOE OSTI2018

Multimodal Communication System

Current communications modules operate as a point-to-point radio. This system operates in a point-to-multipoint utilizing multiple radio frequencies for both high bandwidth data to satellite communication. This communication module further allows for multiple users to interact with the communication system in a true cloud type application so that the modules can be handled in a fleet situation.

Vacaliuc, Bogdan↗
DOE OSTI2018

Normalization of stroboscopic neutron scattering experiments

Neutron scattering studies of kinetic processes are often flux limited. For processes which can be repeated many times, this can be mitigated by stroboscopic reintegration. The recorded scattering events are assigned to different time slices of the process and corresponding slices from all repetitions are summed up. The normalization of such data with respect to the incident beam spectrum can be challenging since the incident neutron flux may not necessarily be evenly distributed over all time slices. Here, in this paper, we discuss how this can result in misleading information and we expand on a technique to amend these issues.

Adlmann, Franz Alois↗
DOE OSTI2017

Determination of the Solid Electrolyte Interphase Structure Grown on a Silicon Electrode Using a Fluoroethylene Carbonate Additive

In this work we explore how an electrolyte additive (fluorinated ethylene carbonate – FEC) mediates the thickness and composition of the solid electrolyte interphase formed over a silicon anode in situ as a function of state-of-charge and cycle. We show the FEC condenses on the surface at open circuit voltage then is reduced to C-O containing polymeric species around 0.9 V (vs. Li/Li + ). The resulting film is about 50 Å thick. Upon lithiation the SEI thickens to 70 Å and becomes more organic-like. With delithiation the SEI thins by 13 Å and becomes more inorganic in nature, consistent with the formation of LiF. This thickening/thinning is reversible with cycling and shows the SEI is a dynamic structure. We compare the SEI chemistry and thickness to 280 Å thick SEI layers produced without FEC and provide a mechanism for SEI formation using FEC additives.

25 ENERGY STORAGE↗
DOE OSTI2015

Towards neutron scattering experiments with sub-millisecond time resolution

Neutron scattering techniques offer several unique opportunities in materials research. However, most neutron scattering experiments suffer from the limited flux available at current facilities. This limitation becomes even more severe if time-resolved or kinetic experiments are performed. A new method has been developed which overcomes these limitations when a reversible process is studied, without any compromise on resolution or beam intensity. We demonstrate that, by recording in absolute time the neutron detector events linked to an excitation, information can be resolved on sub-millisecond timescales. Specifically, the concept of the method is demonstrated by neutron reflectivity measurements in time-of-flight mode at the Liquids Reflectometer located at the Spallation Neutron Source, Oak Ridge National Laboratory, Tennessee, USA, combined with in situ rheometry. Finally, the opportunities and limitations of this new technique are evaluated by investigations of a micellar polymer solution offering excellent scattering contrast combined with high sensitivity to shear.

36 MATERIALS SCIENCE↗
DOE OSTI2014

ADARA

The ADARA software is a collection of programs which gather neutron scattering data from multiple detector banks, multiplex the data into a single stream and distribute that stream to analysis, reduction and translation utilities in real-time.

Miller, Ross↗
DOE OSTI2014

ADARA

The ADARA software is a collection of programs which gather neutron scattering data from multiple detector banks, multiplex the data into a single stream and distribute that stream to analysis, reduction and translation utilities in real-time.

Miller, Ross↗
DOE OSTI2013

Simulink/PARS Integration Support

The state of the art for signal processor hardware has far out-paced the development tools for placing applications on that hardware. In addition, signal processors are available in a variety of architectures, each uniquely capable of handling specific types of signal processing efficiently. With these processors becoming smaller and demanding less power, it has become possible to group multiple processors, a heterogeneous set of processors, into single systems. Different portions of the desired problem set can be assigned to different processor types as appropriate. As software development tools do not keep pace with these processors, especially when multiple processors of different types are used, a method is needed to enable software code portability among multiple processors and multiple types of processors along with their respective software environments. Sundance DSP, Inc. has developed a software toolkit called “PARS”, whose objective is to provide a framework that uses suites of tools provided by different vendors, along with modeling tools and a real time operating system, to build an application that spans different processor types. The software language used to express the behavior of the system is a very high level modeling language, “Simulink”, a MathWorks product. ORNL has used this toolkit to effectively implement several deliverables. This CRADA describes this collaboration between ORNL and Sundance DSP, Inc.

97 MATHEMATICS AND COMPUTING↗