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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Neutron detector development for high-rate neutron reflectometry at the Second Target Station of Oak Ridge National Laboratory

The Second Target Station (STS) at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) is expected to produce a neutron source that is the brightest in the world, having a significantly higher peak brightness compared to the First Target Station (FTS), where the reflectometry instruments already fall short of being able to handle the highest available flux by a factor of ~100. The neutron reflectometers at the SNS FTS are not suitable for the reflectometers planned for the SNS STS because of its unprecedentedly high peak brightness and the already limited capabilities of these instruments at high count rates. Furthermore, the high rate instruments that are now under development are expected to underperform with regard to gamma sensitivity, meaning that signal-to-noise will be reduced and they will be unable to measure weaker reflectance phenomena in the presence of the significant prompt gamma flash at SNS. To address these challenges, we conducted research to advances associated instruments, techniques, and capabilities for the SNS STS reflectometers. More specifically, we investigated the development of a scalable, 2-D positive-sensitive, pixelated, scintillator-based neutron detector module based on a newly developed scintillator. The work has potential for impact on future neutron reflectometry instruments and neutron science performed at the SNS STS. In particular, the improved background rejection capability of the developed detector could extend the available experimental dynamic Q range, allowing it to measure weak reflectance phenomena.

reflectometry, radiation instrumentation, neutron ↗
DOE OSTI2026

Spectral Flux Measurements on SNS Direct Geometry Spectrometers at IRP-2 End-of-Life

The Inner Reflector Plug (IRP) of the Spallation Neutron Source (SNS) was replaced during the SNS shutdown period beginning 25 November 2025. This IRP, IRP-2, was first placed in service in May 2018, and was in use for 42.5 GW-hrs of operation, somewhat longer than its original design life of 30 GW-hrs, or even a refined estimate of 33 GW-hrs for the water moderator poison plate and 39 GW-hrs on the decoupled-poisoned hydrogen moderator decoupler (Gallmeier, Lu, and Iverson 2018). The time-integrated power history for IRP-2 is tracked in Figure 1.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Neutron Positioning and Geometric Distortion Correction on the SNS SiPM Anger Camera

Neutron Anger cameras are scintillator-based thermal neutron detectors that utilize pixelated photosensors to read out visible light signals and position neutrons accurately They are versatile detectors that can cover large areas for diffraction instruments and offer high efficiency and sub-millimeter spatial resolution. Photomultiplier Tube (PMT) based cameras are installed on three instruments at Spallation Neutron Source (SNS). The next generation camera uses Silicon Photomultipliers (SiPMs) instead of PMTs, which allows for a more compact design and higher spatial resolution. In this report, the Gaussian least-squares position fitting method is described in detail, as well as the method used to correct for geometric distortions across the face of the camera. Results from neutron camera tests before and after the distortion correction are shown and the spatial resolution is quantified.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

AutoSAC-Automated Sample Activation Calculation on VULCAN

AutoSAC is an automated python program to conduct sample activation calculation immediately after neutron scattering experiment on VULCAN. AutoSAC takes account of sample dimensions, compositions, forms, sample environments, neutron beam configurations, neutron scattering history, and proton charged resolved beam power etc., and uses a simplified method to rapidly estimate the radioactivity at end of beam or after. It generates a draft report per sample and repository of radioactivity per measurement and provides feedback of current radioactivity and decay time back to a neutron proposal Slack channel to inform users immediately on sample handling. It also utilizes either the sample note field in EPICS or sample composition or thickness correction and takes slack prompt or command to conduct post-beam SAC by demand. The program can be shared to be used in other beamlines at spallation neutron source with modified instrument configurations including instrument specific characteristic beam fluxes.

An, Ke [Oak Ridge National Laboratory (ORNL), Oak ↗
DOE OSTI2025

Characterizing the AFP Spin Flipper for the Nab Experiment

The Nab experiment at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) aims to yield a precise measurement of the electron-neutrino correlation parameter, a , to $\frac{Δa}{a}$ = 1 × 10 −3 from the beta-decay of the free neutron. To achieve Nab’s precision goal, polarization of the neutron beam must be near-zero. A polarizer/analyzer combination, neutron monitors, and an Adiabatic Fast Passage (AFP) spin flipper will be used to determine a beam polarization effectively less than 2 × 10 −5 . Here, I will discuss the initial characterization efforts of the Nab spin flipper as well as plans for further testing.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

What Is the Limit of Quantification for the Minor Phase in Time-of-Flight Neutron Diffraction? A Case Study on Fe and Ni Powder Mixtures at VULCAN

A phase present in small quantities within materials may not simply serve as a secondary component; it can play a crucial role in determining the integrity, properties, and performance of the material. These minor but important phases usually draw attention in material design and processing for fundamental understanding as well as material quality control. Accurately quantifying a minor phase amid a majority phase, especially at extremely low fractions, remains a challenging task. Time-of-flight neutron diffraction, coupled with advanced pattern analysis techniques like Rietveld refinement, is a powerful tool for crystal structure identification and phase quantification. The deep penetrating capability of neutrons enables the detection and quantification of trace phases within materials. In this study, the quantification limits of time-of-flight neutron diffraction were explored using the VULCAN diffractometer at the Spallation Neutron Source, using Fe–Ni powder mixtures as a sample system. By comparing the refinement results to the known weighed values, it was determined that the reliable quantification of a minor Ni phase is achievable down to about 0.1 wt% while a Ni fraction as low as 0.02 wt% is difficult to trace. Effective control of the refinement parameters, especially the profile function parameters, are found to significantly influence the convergence of fittings and the accuracy of phase quantification.

Rietveld refinement↗
DOE OSTI2026

A Smart Vision-Aided RICH (Robotic Interface Control and Handling) System for VULCAN

High-flux neutron beams and high-efficiency detectors enable rapid neutron diffraction measurements at the Engineering Materials Diffractometer (VULCAN) at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory (ORNL). To optimize beam time utilization, efficient sample exchange, alignment, and automated measurements are essential. Recent advances in artificial intelligence (AI) have expanded the capabilities of robotic systems. Here, we report the development of a Robotic Interactive Control and Handling (RICH) system for sample handling at VULCAN, designed to support high-throughput experiments and reduce overhead time. The RICH system employs a six-axis desktop robot integrated with AI-based computer vision models capable of recognizing and localizing samples in real time from instrument and depth-resolving cameras. Vision algorithms combine these detections to align samples with designated measurement positions or place them within complex sample environments such as furnaces. This integration of machine learning-assisted vision with robotic handling demonstrates the feasibility of autonomous sample detection and preparation, offering a pathway toward fully unmanned neutron scattering experiments.

automation↗
DOE OSTI2026

Improvements in the Sample Space for the Backscattering Silicon Spectrometer (BASIS)

The increase in neutron flux at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS), currently operating at 2.0 MW proton beam power, has created new opportunities for higher-throughput neutron scattering experiments while also increasing the importance of minimizing background scattering and optimizing sample-environment operations. To address these challenges on the Backscattering Silicon Spectrometer (BA-SIS), several upgrades were developed and evaluated, including boron carbide (B₄C) masking for flat-plate sample containers, multi-cell sample holders used with a vertically translating sample stick, and an automated helium pump and purge (HPP) system for closed-cycle refrigerators. Neutron diffraction measurements demonstrate that B₄C masks reduce background scattering by 49–67%, outperforming both borated aluminum and boron nitride masks while introducing no additional Bragg reflections within the instrument’s accessible Q-range. Commissioning tests of a double-cell flat-plate sample contain-er showed no measurable crosstalk between adjacent sample compartments and con-firmed stable thermal performance, enabling multiple samples to be measured without re-peated temperature cycling. In addition, the automated HPP system provided reproducible sample-space gas handling with approximately ±1 mbar precision while reducing the need for operator intervention and supporting remote operation. Together, these developments improve signal-to-noise performance, increase experimental throughput, and enhance operational efficiency at BASIS, supporting the instrument’s continued operation under higher neutron flux conditions.

Jalarvo, Niina [ORNL] (ORCID:0000000306446866)↗
DOE OSTI2022

Application of Convolutional and Feedforward Neural Networks for Fault Detection in Particle Accelerator Power Systems

High voltage converter modulators (HVCM) provide power to the accelerating cavities of the spallation neutron source (SNS) facility. HVCM experience catastrophic failures, which increase the downtime of the SNS and reduce beam time. The faults may occur due to different reasons including failures of the resonant capacitor, core saturation due to the magnetic flux, insulated-gate bipolar transistor (IGBT) failures, and others. We recently have setup a HVCM test stand to develop and test machine learning models for anomaly detection and fault prognostics. In this work, we propose binary classifiers and autoencoder architectures based on convolutional (CNN) and feedforward neural networks (FNN) to facilitate distinguishing normal from faulty waveforms coming from the HVCM during operation. The results indicate that the CNN binary classifier is the best model among the four showing very stable performance in the training and testing sets with impressive metrics of precision and recall reaching up to 99\% with a very small uncertainty. The FNN classifier shows the least performance with a large uncertainty in its metrics. The performances of the two autoencoders based on CNN and FNN were in between, showing very good performance nonetheless.

Radaideh, Majdi↗
DOE OSTI2020

Tools to perform data reduction of time-of-flight data taken on BL4A (MagRef)—a Jupyter notebook approach

A collection of modules or tools to produce reflectivity profiles from data acquired with unpolarized and polarized neutron beams using the BL4A (MagRef) instrument at the Spallation Neutron Source. The Jupyter notebook approach offers transparency to the user on what is done with the data, and once the event mode data are stored as NumPy binary files empowers the user to perform the steps from their own laptop without the need for Mantid. The notebook offers two options for background subtraction, applies corrections for the wavelength dependence of the polarizer and flipper efficiencies, accounts for Zeeman energy splitting of the spin-flip channels, Qz-bins the data along contours of constant Qz, propagates errors and writes results in text format suitable for analysis with tools such as GenX.

Fitzsimmons, Michael [Oak Ridge Associated Univ., ↗
DOE OSTI2026

Gigacycle Fatigue Strength Evaluation of Welded 316L Stainless Steels for Mercury Target Vessel

At the Materials and Life Science Experimental Facility (MLF) in J-PARC, liquid mercury target for the pulsed spallation neutron source is in operation. An enclosure vessel for the liquid mercury target made of type 316L stainless steel (SS316L) suffers two kinds of cyclic stress during operation. One is the thermal stress due to the internal heating and swings by proton beam trip. The other is the impulsive stress by the pressure waves generated by the proton beam injection. The total number of loading cycles for the former is ∼104, and the latter is ∼4 × 108 for a year operation in the J-PARC mercury target vessel. The target vessel is assembled by an electron beam welding (EBW) and a gas tungsten arc welding (GTAW). However, fatigue data of welded SS316L up to gigacycle is limited. Ultrasonic fatigue testing, applying load cycles by utilizing ultrasonic resonance, for the welded SS316L was performed to investigate the effect of welding on fatigue behavior up to a gigacycle. The result showed that the fatigue strength degradation by EBW and EBW with GTAW were not recognized up to 109 cycles. Crack initiation in welded specimens nucliated at off-center areas of the specimen whereas the cracks in base metal specimen originated at the specimen center.

Naoe, Takashi [Japan Atomic Energy Agency (JAEA)]↗
NASA NTRS2013

Neutron Characterization for Additive Manufacturing

Oak Ridge National Laboratory (ORNL) is leveraging decades of experience in neutron characterization of advanced materials together with resources such as the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) shown in Fig. 1 to solve challenging problems in additive manufacturing (AM). Additive manufacturing, or three-dimensional (3-D) printing, is a rapidly maturing technology wherein components are built by selectively adding feedstock material at locations specified by a computer model. The majority of these technologies use thermally driven phase change mechanisms to convert the feedstock into functioning material. As the molten material cools and solidifies, the component is subjected to significant thermal gradients, generating significant internal stresses throughout the part (Fig. 2). As layers are added, inherent residual stresses cause warping and distortions that lead to geometrical differences between the final part and the original computer generated design. This effect also limits geometries that can be fabricated using AM, such as thin-walled, high-aspect- ratio, and overhanging structures. Distortion may be minimized by intelligent toolpath planning or strategic placement of support structures, but these approaches are not well understood and often "Edisonian" in nature. Residual stresses can also impact component performance during operation. For example, in a thermally cycled environment such as a high-pressure turbine engine, residual stresses can cause components to distort unpredictably. Different thermal treatments on as-fabricated AM components have been used to minimize residual stress, but components still retain a nonhomogeneous stress state and/or demonstrate a relaxation-derived geometric distortion. Industry, federal laboratory, and university collaboration is needed to address these challenges and enable the U.S. to compete in the global market. Work is currently being conducted on AM technologies at the ORNL Manufacturing Demonstration Facility (MDF) sponsored by the DOE's Advanced Manufacturing Office. The MDF is focusing on R&D of both metal and polymer AM pertaining to in-situ process monitoring and closed-loop controls; implementation of advanced materials in AM technologies; and demonstration, characterization, and optimization of next-generation technologies. ORNL is working directly with industry partners to leverage world-leading facilities in fields such as high performance computing, advanced materials characterization, and neutron sciences to solve fundamental challenges in advanced manufacturing. Specifically, MDF is leveraging two of the world's most advanced neutron facilities, the HFIR and SNS, to characterize additive manufactured components.

Watkins, Thomas↗
NASA NTRS2014

Neutron Imaging for Selective Laser Melting Inconel Hardware with Internal Passages

Additive Manufacturing is showing great promise for the development of new innovative designs and large potential life cycle cost reduction for the Aerospace Industry. However, more development work is required to move this technology into space flight hardware production. With selective laser melting (SLM), hardware that once consisted of multiple, carefully machined and inspected pieces, joined together can be made in one part. However standard inspection techniques cannot be used to verify that the internal passages are within dimensional tolerances or surface finish requirements. NASA/MSFC traveled to Oak Ridge National Lab's (ORNL) Spallation Neutron Source to perform some non-destructive, proof of concept imaging measurements to assess the capabilities to understand internal dimensional tolerances and internal passages surface roughness. This presentation will describe 1) the goals of this proof of concept testing, 2) the lessons learned when designing and building these Inconel 718 test specimens to minimize beam time, 3) the neutron imaging test setup and test procedure to get the images, 4) the initial results in images, volume and a video, 4) the assessment of using this imaging technique to gather real data for designing internal flow passages in SLM manufacturing aerospace hardware, and lastly 5) how proper cleaning of the internal passages is critically important. In summary, the initial results are very promising and continued development of a technique to assist in SLM development for aerospace components is desired by both NASA and ORNL. A plan forward that benefits both ORNL and NASA will also be presented, based on the promising initial results. The initial images and volume reconstruction showed that clean, clear images of the internal passages geometry are obtainable. These clear images of the internal passages of simple geometries will be compared to the build model to determine any differences. One surprising result was that a new cleaning process was used on these simply geometric specimens that resulted in what appears to be very smooth internal surfaces, when compared to other aerospace hardware cleaning methods.

Tramel, Terri L.↗
DOE OSTI2020

Control System Plans for SNS Upgrade Projects

The Spallation Neutron Source at Oak Ridge National Laboratory is planning two major upgrades to the facility. The Proton Power Upgrade project, currently underway, will double the machine power from 1.4 to 2.8 MW by adding seven additional cryomodules and associated equipment. The Second Target Station project, currently in conceptual design, will construct a new target station effectively doubling the potential scientific output of the facility. This paper discusses the control system upgrades required to integrate these projects into the existing EPICS based control systems used for the machine and neutron instrument beamlines. While much of the control system can be replicated from existing solutions, some systems require new hardware and software. Operating two target stations simultaneously will require a new run permit system to safely manage beam delivery.

Hartman, Steven↗
DOE OSTI2021

Bubble Generation in the SNS 2 MW Mercury Target

The accelerator at the Spallation Neutron Source is currently being upgraded to increase the proton beam power from 1.4 MW to 2.8 MW. About 2 MW will go to the first target station, while the rest will go to the future second target station. The first target station uses a mercury target. When the short proton beam pulse hits it, strong pressure waves are developed inside the mercury and the vessel itself, causing weld failures and cavitation erosion. The pressure wave can be significantly mitigated by injecting small helium bubbles into the mercury. SNS has been injecting helium since 2017 using small orifices but has met challenges in fabrication and operations with them. Thus, for the 2 MW target, swirl bubblers will be used to increase gas injection and improve reliability. A 2 MW prototypical target was built and tested in a mercury process loop available at Oak Ridge National Laboratory. Acrylic viewports on the top of the target were used to determine the bubble size distribution (BSD) generated by the swirl bubblers. It was found that the bubblers were not only capable of generating small bubbles but that the BSD was independent of gas injection rate.

Barbier, Charlotte↗
DOE OSTI2021

SNS Credited Beam Power Limit System Preliminary Design

The Controls Group at the Spallation Neutron Source (SNS) is designing a programmable signal processor based credited safety control that calculates pulsed beam power based on beam kinetic energy and charge. The system must reliably shut off the beam if the average power exceeds 2.145 MW averaged over 60 seconds. This paper discusses architecture and design choices needed to develop the system under the auspices of a programmable radiation-safety credit control.

Deibele, Craig↗
DOE OSTI2022

Radiation hardened beam instrumentations for multi-Mega-Watt beam facilities

The radiation hardened beam instrumentations workshop was held on February 3rd and 4th, 2022 to identify the technological challenges on the beam instrumentation for multi-Mega-Watt (MW) beam facilities. We invited a speaker from a high energy neutrino beam facility (CERN, Fermilab and J-PARC), a collider detector group (CERN and Fermilab), a neutron spallation source facility (ESS, J-PARC and SNS), and a rare-isotope beam facility (FRIB). Although, the operational beam parameter for each institution is unique due to their different physics goals, we realize that there is a common issue on the beam instrumentation. Therefore, it will be tackled by a collaborative R&D effort among facilities. We summarize an output from the workshop in the paper, and propose a possible R&D for the future radiation hardened beam instrumentations with a global effort.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Modernizing the SNS Control System

The Spallation Neutron Source at Oak Ridge National Laboratory has been operating since 2006. An upgrade to double the machine power from 1.4 MW to 2.8 MW is currently underway and a project to add a second target station is in the preliminary design phase. While each project will add the controls needed for their specific scope, the existing control system hardware, software, and infrastructure require upgrades to maintain high availability and ensure the system will meet facility requirements into the future. While some systems have received new hardware due to obsolescence, much of the system is original apart from some maintenance and technology refresh. Software will also become obsolete and must be upgraded for sustainability. Further, requirements for system capacity can be expected to increase as more subsystems upgrade to smarter devices capable of higher data rates. This paper covers planned improvements to the integrated control system with a focus on reliability, sustainability, and future capability.

White, Karen S.↗