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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

rustpix

rustpix is a high-performance, open-source Rust library with first-class Python bindings (via PyO3) for processing pixel-detector data in neutron imaging. It targets time-stamping detectors such as Timepix3 (TPX3) at ORNL's Spallation Neutron Source (VENUS beamline), where each detected neutron deposits charge across a cluster of pixels within a very high-rate event stream (96M+ hits/sec). rustpix parses TPX3 event data in parallel using memory-mapped I/O, offers four interchangeable clustering algorithms (ABS adjacency-based search, DBSCAN, graph/union-find connected components, and a parallel grid method), and extracts weighted, super-resolved centroids to produce neutron-event lists. A streaming architecture lets it process files larger than available memory. rustpix is distributed as a pip-installable Python package (with NumPy integration), Rust crates, a command-line tool, and an interactive GUI; it writes HDF5, Apache Arrow, and CSV; and it is designed to extend to TPX4 and other detector types. Released as open-source under the MIT License.

Zhang, Chen [Oak Ridge National Laboratory (ORNL),↗
DOE OSTI2012

BEAM LOSS MECHANISMS IN HIGH INTENSITY LINACS

In the present operation of the Oak Ridge Spallation Neutron Source, 60-Hz, 825-us H beam pulses are accelerated to 910 MeV, and then compressed to less than a microsecond in the storage ring, to deliver 1 MW of beam power to the spallation target. The beam loss in the superconducting portion of the linac is higher than expected, and it has shown a surprising counter-intuitive correlation with quadrupole magnetic fields, with a loss minimum occurring when the quadrupoles are set to approximately half their design values. This behavior can now be explained by a recent set of experiments that show the beam loss is primarily due to intra-beam stripping. Beam halo is another important beam loss contributor, and collimation in the 2.5 MeV Medium Energy Beam Transport has proven to be an effective mitigation strategy. In this presentation, we will summarize these and other beam loss mechanisms that are important for high intensity linacs.

Plum, Michael A↗
NASA NTRS1994

Cosmic ray models for early galactic lithium, beryllium, and boron production

To better understand the early galactic production of Li, Be, and B by cosmic ray spallation and fusion reactions, the dependence of these production rates on cosmic ray models and model parameters is examined. The sensitivity of elemental and isotropic production to the cosmic ray pathlength magnitude and energy dependence, source spectrum spallation kinematics, and cross section uncertainties is studied. Changes in these model features, particularly those features related to confinement, are shown to alter the Be- and B-versus-Fe slopes from a naive quadratic relation. The implications of our results for the diffuse gamma-ray background are examined, and the role of chemical evolution and its relation to our results is noted. It is also noted that the unmeasured high energy behavior of alpha + alpha fusion can lead to effects as large as a factor of 2 in the resultant yields. Future data should enable Population II Li, Be, and B abundances to constrain cosmic ray models for the early Galaxy.

Fields, Brian D.↗
DOE OSTI2020

Upgrading the LANSCE accelerator with a SNS RF-driven H− ion source

The LANSCE accelerator is currently powered by a filament-driven, biased converter-type H− ion source that operates at 10%, the highest plasma duty factor for this type of source, using only ∼2.2 SCCM of H2. The ion source needs to be replaced every 4 weeks, which takes up to 4 days. The measured negative beam current of 12–16 mA falls below the desired 24 mA acceptance of the LANCSE accelerator. The SNS (Spallation Neutron Source) RF-driven, H− ion source injects ∼50 mA of H− beam into the SNS accelerator at 60 Hz with a 6% duty factor and an availability of >99.5% but requires ∼30 SCCM of H2. Up to 7 A h of H− have been produced during the 14-weeks-long source service cycles, which is unprecedented for small emittance, high-current, pulsed H− ion sources. The emittance of the SNS source is slightly smaller than the emittance of the LANSCE source. The SNS source also features unrivaled low Cs consumption and can be installed and started up in <12 h. LANSCE and SNS are working toward the use of SNS H− ion sources on the LANSCE accelerator because they could (a) fill the LANSCE accelerator to its capacity, (b) decrease the source replacement time by a factor of up to 7, and (c) increase source lifetime by a factor of about 4. This paper discusses some of the challenges that emerge when trying to match a different H− source into an existing injector with significantly different characteristics and operating regimes.

Stockli, Martin P.↗
DOE OSTI2011

WORKER INHALATION DOSE COEFFICIENTS FOR RADIONUCLIDES NOT PREVIOUSLY IDENTIFIED IN ICRP PUBLICATION 68

While inhalation dose coefficients are provided for about 800 radionuclides in International Commission on Radiological Protection (ICRP) Publication 68, many radionuclides of practical dosimetric interest for facilities such as high-energy proton accelerators are not specifically addressed, nor are organ-specific dose coefficients tabulated. The ICRP Publication 68 methodology is used, along with updated radiological decay data and metabolic data, to identify committed equivalent dose coefficients [hT(50)] and committed effective dose coefficients [e(50)] for radionuclides produced at the Oak Ridge National Laboratory’s Spallation Neutron Source.

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1994

Cosmic-ray models for early Galactic Lithium, Beryllium, and Boron production

To understand better the early Galactic production of Li, Be, and B by comsmic-ray spallation and fusion reactions, the dependence of these production rates on cosmic-ray models and model parameters is examined. The sensitivity of elemental and isotopic production to the cosmic-ray path length magnitude and energy dependence, source spectrum, spallation kinematics, and cross section uncertainties is studied. Changes in these model features, particularly those features related to confinement, are shown to alter the Be- and B- versus-Fe slopes from a naive quadratic relation. The implications of our results for the diffuse gamma-ray background are examined, and the role of chemical evolution and its relation to our results is noted. It is also noted that the unmeasured high-energy behavior of alpha + alpha fusion can lead to effects as large as a factor of 2 in the resultant yields. Future data should enable Population II Li, Be, and B abundances to constrain cosmic-ray models for the early Galaxy.

Fields, Brian D.↗
DOE OSTI2020

On single-crystal neutron-diffraction in DACs: quantitative structure refinement of light elements on SNAP and TOPAZ

Quantitative single crystal neutron-diffraction in diamond anvil cells has so far been limited by the neutron flux available at the various neutron sources. As a result, highly precise measurements of the exact position of light elements have not been possible preventing, for example, structural studies of hydrogen and hydrogen bonds under pressure. Here we report experiments carried out on SNAP at the Spallation Neutron Source (ORNL, TN, USA) to explore the possibility and current limits of such studies. Furthermore, we benchmarked the obtained data quality with reference experiments carried out on TOPAZ, a dedicated single-crystal instrument.We show that measuring single-crystal diffraction intensities on SNAP is possible to such a precision that we are able to resolve the hydrogen bonds in potassium dideuterium phosphate (DKDP) as well as in ice VI.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Selected advances in small-angle scattering and applications they serve in manufacturing, energy and climate change

Innovations in small-angle X-ray and neutron scattering (SAXS and SANS) at major X-ray and neutron facilities offer new characterization tools for researching materials phenomena relevant to advanced applications. For SAXS, the new generation of diffraction-limited storage rings, incorporating multi-bend achromat concepts, dramatically decrease electron beam emittance and significantly increase X-ray brilliance over previous third-generation sources. This results in intense X-ray incident beams that are more compact in the horizontal plane, allowing significantly improved spatial resolution, better time resolution, and a new era for coherent-beam SAXS methods such as X-ray photon correlation spectroscopy. Elsewhere, X-ray free-electron laser sources provide extremely bright, fully coherent, X-ray pulses of <100 fs and can support SAXS studies of material processes where entire SAXS data sets are collected in a single pulse train. Meanwhile, SANS at both steady-state reactor and pulsed spallation neutron sources has significantly evolved. Developments in neutron optics and multiple detector carriages now enable data collection in a few minutes for materials characterization over nanometre-to-micrometre scale ranges, opening up real-time studies of multi-scale materials phenomena. SANS at pulsed neutron sources is becoming more integrated with neutron diffraction methods for simultaneous structure characterization of complex materials. In this paper, selected developments are highlighted and some recent state-of-the-art studies discussed, relevant to hard matter applications in advanced manufacturing, energy and climate change.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Recent developments of MCViNE and its applications at SNS

Abstract MCViNE is an open source, object-oriented Monte Carlo neutron ray-tracing simulation software package. Its design allows for flexible, hierarchical representations of sophisticated instrument components such as detector systems, and samples with a variety of shapes and scattering kernels. Recently this flexible design has enabled several applications of MCViNE simulations at the Spallation Neutron Source (SNS) at Oak Ridge National Lab, including assisting design of neutron instruments at the second target station and design of novel sample environments, as well as studying effects of instrument resolution and multiple scattering. Here we provide an overview of the recent developments and new features of MCViNE since its initial introduction (Jiao et al 2016 Nucl. Instrum. Methods Phys. Res., Sect. A 810 , 86–99), and some example applications.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Ultrafast low-temperature metal–insulator interface phonon dynamics and heat transport in a Pt/Gd 3 Fe 5 O 12 heterostructure

Interfacial thermal and acoustic phenomena have an important role in quantum science and technology, including in spintronic and spincaloritronic materials and devices. Simultaneous measurements of the low-temperature thermal and acoustic properties of a metal/insulator heterostructure reveal distinct dynamics in the characteristic phonon frequency ranges of acoustic and thermal transport. The measurements probed a heterostructure consisting of a thin film of Pt on the ferrimagnetic insulator gadolinium iron garnet (Gd 3 Fe 5 O 12 , GdIG) grown epitaxially on a gadolinium gallium garnet substrate. Ultrafast structural dynamics within the Pt layer were tracked using time-resolved ultrafast x-ray diffraction and analyzed to probe interfacial acoustic and thermal properties. The rapid heating of the Pt layer by a 400 nm wavelength femtosecond-duration optical pulse produced transient structural changes that provided the stimulus for these measurements. Rapid heating produced a broadband acoustic pulse that was partially reflected by the Pt/GdIG interface. Temporal frequencies up to 740 GHz, corresponding to angular frequencies of several THz, were detected in a wavelet analysis of the acoustic oscillations of the strain in the Pt layer. The structural results were analyzed to determine (i) the acoustic damping coefficient and phonon mean free path in Pt at frequencies of hundreds of GHz and (ii) the Grüneisen anharmonicity parameter. The thermal conductance of the Pt/GdIG interface was tracked using the slower, tens-of-picosecond-scale, dynamics of the initial cooling of the heated Pt layer. Analysis using a model based on the Boltzmann transport equation shows that the phonon transmission is lower at the phonon frequencies relevant to thermal transport than for subterahertz regime acoustics.

Acoustic phenomena↗
DOE OSTI2022

Report from: US Muon Workshop 2021: A Road Map for a Future Muon Facility February 1-2, 2021

The workshop titled “US Muon Workshop 2021: A road map for a future Muon Facility” was held virtually on February 1-2, 2021. The workshop aimed to bring together world experts in muon spectroscopy (µSR) and other techniques along with interested stakeholders to evaluate the scientific need to construct a new µSR facility in the United States (US). The more than 200 participants highlighted several key scientific areas for µSR research, including quantum materials, hydrogen chemistry, and battery materials, and how each area could benefit from a new, high flux pulsed muon source. Experts also discussed aspects of the µSR technique, such as low-energy µSR, novel software developments, and beam and detector technologies that could enable revolutionary advances in µSR at a next-generation facility. The workshop concluded with discussion of a concept being developed for a new µSR facility at the Spallation Neutron Source (SNS) of Oak Ridge National Laboratory (ORNL). That novel design concept was first envisioned by many of the same µSR experts at a workshop held previously at ORNL in 2016. The participants expressed that the current design had the potential to be a world-leading µSR facility, and strongly encouraged the principal investigators to continue their work in order to refine the concept and determine instrument parameters that would enable new scientific opportunities

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

US Muon Workshop 2021: A road map for a future Muon Facility

The workshop title “US Muon Workshop 2021: A road map for a future Muon Facility” was held virtually on February 1-2, 2021. The workshop aimed to bring together world experts in muon spectroscopy (µSR) and other techniques along with interested stakeholders to evaluate the scientific need to construct a new µSR facility in the United States (US). The more than 200 participants highlighted several key scientific areas for µSR research, including quantum materials, hydrogen chemistry, and battery materials, and how each area could benefit from a new, high flux pulsed muon source. Experts also discussed aspects of the µSR technique, such as low-energy µSR, novel software developments, alongside beam and detector technologies, that could enable revolutionary advances in µSR at a next-generation facility. The workshop concluded with discussion of a concept being developed for a new µSR facility at the Spallation Neutron Source (SNS) of Oak Ridge National Laboratory (ORNL). That novel design concept was first envisioned by many of the same µSR experts at a workshop held previously at ORNL in 2016. The participants expressed that the current design had the potential to be a world-leading µSR facility, and strongly encouraged the principal investigators to continue their work in order to refine the concept and determine instrument parameters that would enable new scientific opportunities.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Coherent Elastic Neutrino Nucleus Scattering

Coherent Elastic Neutrino Nucleus Scattering (CENNS) has yet to be observed since its first prediction in 1974. The CENNS cross-section is precisely known in the Standard Model (SM). It is considerably larger than the other neutrino interaction channels at MeV energies. If measured at its predicted value, CENNS can be a very powerful tool for future neutrino oscillation experiments. Alternatively, any deviation from the very robust SM prediction could be a window to beyond-SM physics. The discovery of CENNS requires an intense source of low energy neutrinos, and a large-scale low energy threshold detector, both of which complement and build on existing programs at Fermilab. The Booster Neutrino Beamline (BNB) at Fermilab is a surprisingly powerful source of pion decay-at-rest ($\pi$DAR) neutrinos. The energy spectrum and flux of neutrinos in the backward direction (far-off-axis) of the BNB is excellent for a CENNS discovery measurement. At the closest practical location, the $\pi$DAR neutrino flux at BNB would be about a fifth of the neutrino flux of Spallation Neutron Source (SNS at Oak Ridge). The BNB site is preferable in almost every other aspect, however. First, the beam duty factor of BNB (2.5x10 -5 ) is about a factor of four better, which will help to reduce ambient backgrounds. Second, the potential experiment site, close to the BNB target, allows optimal placement of the detectors, with minimal sitting issues. The CENNS experiment would be completely parasitic to any running of the BNB. It would require no changes to the beamline, and place no additional requirements on the running mode or times. The $\pi$DAR neutrinos from the BNB are a by-product of running the beamline for MicroBooNE, and will be available for the foreseeable future. The CENNS detector would be a ton-scale single-phase Liquid Argon (LAr) detector, placed inside a water shield with an active cosmic ray veto. The low energy threshold and low background detector technology is already well developed thanks to work over the last decade in Dark Matter detector physics. Moreover, Fermilab is equipped with very strong technical and engineering resources in liquid argon detector development. One issue that must be addressed prior to the development of a full CENNS proposal is the question of whether the beam-related fast neutron background is low enough that it can be practically shielded.

Brice, S. J.↗
DOE OSTI2016

Helium-3 Production via Lithium-6 Activation in an Accelerator-Driven Reactor

In this paper, the possibility of using an accelerator-driven subcritical reactor to produce helium-3 is explored. Current supply of helium-3 in the United States is running low. Helium-3 has many applications in neutron detection, high-energy physics, and national security, and has a growing demand in the scientific community for its properties. The main source of helium-3 in the United States is from dismantling nuclear arms, where tritium is allowed to decay into helium-3. There are no current, significant future plans for increasing helium-3 production. However, the projected demand of this isotope is expected to increase dramatically, with greater research into aneutronic fusion, and allotments of helium for the Spallation Neutron Source, and ITER expected in years to come. Tritium, with a half-life of 12.3 years, will take time to decay to helium-3, which means production needs to start now to counter the future deficit. This helium-3 production system sets out to be an economical, and safe solution for this future deficit. A zirconium-lithium mixture is utilized as a target for breeding helium-3. Specifically, the target rods will consist of lithium aluminate pellets with diameters ranging from 100 to 500 microns, dispersed within a zirconium matrix. Lithium targets in pellet form were chosen over a solid rod, or annulus, in order to reduce self-shielding effects within the lithium, and to further facilitate tritium loading and containment within the zirconium. Additionally, a stainless steel 316 cladding surrounds the target rods, to further reduce outgassing of helium. The core is made up of 6480 fuel pins, enriched to 4.75% wt% U-235/U, and 3660 lithium pins in mixed assemblies arranged in hexagonal lattices, with the lithium enriched to 75% lithium-6, and a total lithium loading of approximately 70 kg. An accelerator is used as a neutron source, firing 800 MeV protons at a liquid lead target loop. Neutronics analysis and burnup calculation were performed with the aid of MCNP6. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

AGES: Automated Gas Environment System for in situ neutron powder diffraction

High fluxes available at modern neutron and synchrotron sources have opened up a wide variety of in situ and operando studies of real processes using scattering techniques. This has allowed the user community to follow chemistry in the beam, which often requires high temperatures, gas flow, etc. In this paper, we describe an integrated gas handling system for the general-purpose powder diffraction beamline Powgen at the Spallation Neutron Source. The Automated Gas Environment System (AGES) allows control of both gas flow and temperature (room temperature to 850 °C), while measuring the partial pressure of oxygen and following the effluent gas by mass spectrometry, concurrent with neutron powder diffraction, in order to follow the structural evolution of materials under these conditions. The versatility of AGES is illustrated by two examples of experiments conducted with the system. In solid oxide fuel cell electrode materials, oxygen transport pathways in double perovskites PrBaCo 2 O 5+δ and NdBaCo 2 O 5+δ were elucidated by neutron diffraction measurements under atmosphere with oxygen partial pressures (pO 2 ) of 10 –1 to 10 –4 (achieved using mixtures of nitrogen and oxygen) and temperatures from 575 to 850 °C. In another example, the potential oxygen storage material La 1–x Sr x FeO 3 was measured under alternating flows of 15% CH 4 in N 2 and air (20% O 2 in N 2 ) at temperatures from 135 to 835 °C. As a result, from the oxygen stoichiometry, the optimal composition for oxygen storage was determined.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Second Target Station High-Fidelity Target Activation Comparison

The development of the Second Target Station (STS) target system at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) is well underway. The target system at STS consists of a rotating target disk that contains 21 segments of tungsten clad in tantalum clad in steel. A key aspect of the design of the target system is to account for the delayed heating and material damage caused by the delayed dose from decaying radionuclides. These radionuclides are a product of either spallation reactions or transmutation of the nuclei in the target system. These radionuclides build up in the target system components over the lifetime of the facility, and the radiation that is emitted can deposit energy in the components causing significant component heating and material damage. Monte Carlo N-Particle (MCNP) Version 6.2 transports the various particle species and calculates the spallation products and neutron fluxes throughout the target system. These spallation products and neutron fluxes along with the material definition of each component are relayed to the CINDER2008 transmutation code to calculate the radionuclide inventories and the corresponding decay gamma emission spectra. MCNP6.2 coupled with CINDER2008 is the computational method-of-choice for the analysis discussed in the following sections of this report. The analysis focuses on validating major assumptions in calculating the radionuclide inventory in the STS target system: all of the target segments are fresh, unirradiated material when the protons are incident on the segment, the average of the 21 segments of the target is sufficient to represent a single segment, and that averaging the proton pulse structure over time does not significantly affect the radionuclide inventory. The position-averaged, high-fidelity, and single-tally computational methods are used to validate the assumptions and provide a point of comparison to evaluate how the assumptions impact the radionuclide inventories. A more detailed explanation of the three computational methods is provided in Section 2. The position-averaged and single-tally methods are less computationally expensive when compared with the high-fidelity method where 54,000 individual calculations are needed to calculate 1 hr of STS operation. Section 3 details the comparison of the three methods to show that the assumptions made in the position-averaged method do not significantly impact the radionuclide inventory after 1 hr of operation. The discussions and results in this report are for 1 hr of operation. Due to the computational cost associated with calculating the transmutation and activation using the high-fidelity method, only 1 hr of operation has been calculated. The discrepancies observed after 1 hr of operation are not extrapolated out to longer operational times, and this report does not address how the discrepancies between the computational methods may manifest for longer operational periods.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Extreme Temperature Sample Environment for Materials Research Using Neutron Scattering

Extreme temperatures and non-equilibrium materials are both central to Department of Energy’s (DOE) mission of addressing grand challenges in emerging energy and advanced materials technologies. The goal of this project is to develop and perfect a system for studying materials in extreme and non-equilibrium conditions using neutron scattering. Neutron scattering has many advantages in the study of materials structure including the ability to use isotopic substitution to determine partial structure factors. When used at a pulsed neutron source, the potential for event-based detection can enable a stroboscopic technique to interrogate very short lived metastable states in supercooled liquids. The work performed in this Phase I project included: (i) literature reviews and discussions with beamline scientists to establish key requirements for the instrument, (ii) laboratory-based research at Materials Development, Inc. (MDI) to test design concepts, modify control software and model designs, (iii) feasibility experiments and measurements on a prototype sample at the Spallation Neutron Source, and (iv) analysis of the results and design of the proposed Phase II instrument. The results of the work show that the proposed approach is viable and provides a strong basis for the Phase II instrument design and Phase III commercialization. MDI participated in the DOE Commercialization Assistance Program with the Larta Institute (Larta) to accelerate commercial sales of the instruments. The market research identified a served available market of ~13M including sales to beamlines, university research laboratories, and industrial glass and materials businesses. Over the ca. 10 year product life cycle, MDI expects to sell instruments with a cumulative net present value profit of approximately 5M.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Cross-Cutting Software Solutions in Support of Experimental Analysis Challenges at National Scattering Facilities

Rapid improvements in instrumentation at neutron and light source combined with new capabilities in computing, data analytics, and machine learning offer unprecedented scientific capabilities to address fundamental and applied science questions in a wide area of subjects from quantum materials to biological systems. In order to make these capabilities accessible to the broader scientific community, significant developments are needed related to workflow spanning from experimental control to advanced materials simulations as well as the underpinning scientific software. In this chapter, we explore these needs and recent developments at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. A central part of the workflow at the SNS is the data reduction framework Mantid which is developed as a partnership between European and US neutron-scattering facilities.

Proffen, Thomas↗