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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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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

The hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: “V”-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on the variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Measurement and Analysis of Gamma-Rays Emitted From Spent Nuclear Fuel Above 3 MeV

The gamma-ray spectrum of spent nuclear fuel in the 3- to 6-MeV energy range is important for active interrogation since emitted gamma rays emitted from nuclear decay are not expected to interfere with measurements in this energy region. There is, unfortunately, a dearth of empirical measurements from spent nuclear fuel in this region. This work is an initial attempt to partially ll this gap by presenting an analysis of gamma-ray spectra collected from a set of spent nuclear fuel sources using a high-purity germanium detector array. This multi-crystal array possesses a large collection volume, providing high energy resolution up to 16 MeV. The results of these measurements establish the continuum count-rate in the energy region between 3- and 6-MeV. Also assessed is the potential for peaks from passive emissions to interfere with peak measurements resulting from active interrogation delayed emissions. As one of the first documented empirical measurements of passive emissions from spent fuel for energies above 3 MeV, this work provides a foundation for active interrogation model validation and detector development.

delayed gamma rays↗
DOE OSTI2017

Muon flux measurements at the davis campus of the sanford underground research facility with the majorana demonstrator veto system

We report the first measurement of the muon flux underground at the Davis Campus of the Sanford Underground Research Facility at the 4850 foot level. Measurements were done with the Majorana Demonstrator veto system arranged in two different configurations. Both results are in agreement within statistical accuracy. The measured flux is (4.08+-0.19) x 10 -9 muons/cm/2. We compare our results with previous calculations.

Abgrall, N.↗
DOE OSTI2014

Plutonium measurements with a fast-neutron multiplicity counter for nuclear safeguards applications

Measurements were performed at the Joint Research Centre in Ispra, Italy to field test a fast-neutron multiplicity counter developed at the University of Michigan. The measurements allowed the assessment of the system's photon discrimination abilities, efficiency when measuring neutron multiplicity, ability to characterize 240 Pu eff mass, and performance relative to a currently deployed neutron coincidence counter. We describe how this work is motivated by the need to replace and improve upon 3 He neutron detection systems for nuclear safeguards applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Measurements of electron transport in liquid and gas Xenon using a laser-driven photocathode

Measurements of electron drift properties in liquid and gaseous xenon are reported. The electrons are generated by the photoelectric effect in a semitransparent gold photocathode driven in transmission mode with a pulsed ultraviolet laser. The charges drift and diffuse in a small chamber at various electric fields and a fixed drift distance of 2.0 cm. At an electric field of 0.5 kV/cm, the measured drift velocities and corresponding temperature coefficients respectively are 1.97 ± 0.04 mm/µs and (-0.69 ± 0.05)%/K for liquid xenon, and 1.42 ± 0.03 mm/µs and (+0.11 ± 0.01)%/K for gaseous xenon at 1.5 bar. In addition, we measure longitudinal diffusion coefficients of 25.7±4.6 cm2/s and 149±23 cm2/s, for liquid and gas, respectively. The quantum efficiency of the gold photocathode is studied at the photon energy of 4.73 eV in liquid and gaseous xenon, and vacuum. These charge transport properties and the behavior of photocathodes in a xenon environment are important in designing and calibrating future large scale noble liquid detectors.

Njoya, Oumarou↗
DOE OSTI2015

The use of aluminum nitride to improve Aluminum-26 Accelerator Mass Spectrometry measurements and production of Radioactive Ion Beams

We present results and discuss the use of aluminum nitride as a promising source material for Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beams (RIBs) science applications of 26 Al isotopes. The measurement of 26 Al in geological samples by AMS is typically conducted on Al 2 O 3 targets. However, Al 2 O 3 is not an ideal source material because it does not form a prolific beam of Al- required for measuring low-levels of 26 Al. Multiple samples of aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), mixed Al 2 O 3 –AlN as well as aluminum fluoride (AlF 3 ) were tested and compared using the ion source test facility and the stable ion beam (SIB) injector platform at the 25-MV tandem electrostatic accelerator at Oak Ridge National Laboratory. Negative ion currents of atomic and molecular aluminum were examined for each source material. It was found that pure AlN targets produced substantially higher beam currents than the other materials and that there was some dependence on the exposure of AlN to air. The applicability of using AlN as a source material for geological samples was explored by preparing quartz samples as Al 2 O 3 and converting them to AlN using a carbothermal reduction technique, which involved reducing the Al 2 O 3 with graphite powder at 1600 °C within a nitrogen atmosphere. The quartz material was successfully converted to AlN. Thus far, AlN proves to be a promising source material and could lead towards increasing the sensitivity of low-level 26 Al AMS measurements. The potential of using AlN as a source material for nuclear physics is also very promising by placing 26 AlN directly into a source to produce more intense radioactive beams of 26 Al.

Janzen, Meghan S.↗
DOE OSTI2025

Neutron capture measurements at UMass lowell research reactor

A new facility was designed around the thermal column beam port of the 1 MW Research Reactor at the University of Massachusetts Lowell. Thermal neutrons are collimated to a 1-inch diameter beam and incident on samples to induce the radiative neutron capture. New measurements of capture gamma rays are planned for Mn, Cu, Ni, Cr, and Gd samples in the next few years. The experiments will be carried out in close collaboration with the ENSDF (Evaluated Nuclear Structure Data File) evaluation group at Brookhaven National Laboratory. The gamma rays are measured using an array of high-resolution HPGe detectors. Some of the HPGe detectors use active Compton shields that were designed from scintillation detectors and improve significantly the signal-to-background in the measured gamma-ray spectra with HPGe. The experimental spectra will be validated by the GEANT4 simulations of the array and theoretical models of the emission of gamma rays from the compound nucleus. In conclusion, the new experimental results on the capture gamma ray intensities will be incorporated in future ENSDF evaluations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Nanophotonic Atomic Force Microscope Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale [Nanophotonic AFM Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale]

The atomic force microscope (AFM) offers a rich observation window on the nanoscale, yet many dynamic phenomena are too fast and too weak for direct AFM detection. Integrated cavity-optomechanics is revolutionizing micromechanical sensing; however, it has not yet impacted AFM. Here, we make a groundbreaking advance by fabricating picogram-scale probes integrated with photonic resonators to realize functional AFM detection that achieve high temporal resolution (<10 ns) and picometer vertical displacement uncertainty simultaneously. The ability to capture fast events with high precision is leveraged to measure the thermal conductivity (η), for the first time, concurrently with chemical composition at the nanoscale in photothermal induced resonance experiments. The intrinsic η of metal–organic-framework individual microcrystals, not measurable by macroscale techniques, is obtained with a small measurement uncertainty (8%). The improved sensitivity (50×) increases the measurement throughput 2500-fold and enables chemical composition measurement of molecular monolayer-thin samples. In conclusion, our paradigm-shifting photonic readout for small probes breaks the common trade-off between AFM measurement precision and ability to capture transient events, thus transforming the ability to observe nanoscale dynamics in materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Measuring error rates of mid-circuit measurements

High-fidelity mid-circuit measurements, which read out the state of specific qubits in a multiqubit processor without destroying them or disrupting their neighbors, are a critical component for useful quantum computing. They enable fault-tolerant quantum error correction, dynamic circuits, and other paths to solving classically intractable problems. But there are few methods to assess their performance comprehensively. In this work, we address this gap by introducing the first randomized benchmarking protocol that measures the rate at which mid-circuit measurements induce errors in many-qubit circuits. Using this protocol, we detect and eliminate previously undetected measurement-induced crosstalk in a 20-qubit trapped-ion quantum computer. Then, we use the same protocol to measure the rate of measurement-induced crosstalk error on a 27-qubit IBM Q processor, and quantify how much of that error is eliminated by dynamical decoupling.

Hothem, Daniel [Sandia National Laboratories (SNL-↗
DOE OSTI2021

Measurement of the proton spin structure at long distances

Measuring the spin structure of protons and neutrons tests our understanding of how they arise from quarks and gluons, the fundamental building blocks of nuclear matter. At long distances, the coupling constant of the strong interaction becomes large, requiring non-perturbative methods to calculate quantum chromodynamics processes, such as lattice gauge theory or effective field theories. In this work, we report proton spin structure measurements from scattering a polarized electron beam off polarized protons. The spin-dependent cross-sections were measured at large distances, corresponding to the region of low momentum transfer squared between 0.012 and 1.0GeV 2 . This kinematic range provides unique tests of chiral effective field theory predictions. Our results show that a complete description of the nucleon spin remains elusive, and call for further theoretical works, for example, in lattice quantum chromodynamics. Finally, our data extrapolated to the photon point agree with the Gerasimov–Drell–Hearn sum rule, a fundamental prediction of quantum field theory that relates the anomalous magnetic moment of the proton to its integrated spin-dependent cross-sections.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurement of the refractive index dispersion of As{sub 2}Se{sub 3} bulk glass and thin films prior to and after laser irradiation and annealing using prism coupling in the near- and mid-infrared spectral range

The prism coupling technique has been utilized to measure the refractive index in the near- and mid-IR spectral region of chalcogenide glasses in bulk and thin film form. A commercial system (Metricon model 2010) has been modified with additional laser sources, detectors, and a new GaP prism to allow the measurement of refractive index dispersion over the 1.5-10.6 {mu}m range. The instrumental error was found to be {+-}0.001 refractive index units across the entire wavelength region examined. Measurements on thermally evaporated AMTIR2 thin films confirmed that (i) the film deposition process provides thin films with reduced index compared to that of the bulk glass used as a target, (ii) annealing of the films increases the refractive index of the film to the level of the bulk glass used as a target to create it, and (iii) it is possible to locally increase the refractive index of the chalcogenide glass using laser exposure at 632.8 nm.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch

Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian function associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. These measurements are used to gain a better understanding of Z-pinch equilibria.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

X-ray Thomson scattering measurements of temperature and density from multi-shocked CH capsules

Proof-of-principle measurements of the electron densities, temperatures, and ionization states of spherically compressed multi-shocked CH (polystyrene) capsules have been achieved using spectrally resolved x-ray Thomson scattering. A total energy of 13.5 kJ incident on target is used to compress a 70 μm thick CH shell above solid-mass density using three coalescing shocks. Separately, a laser-produced zinc He-α x-ray source at 9 keV delayed 200 ps-800 ps after maximum compression is used to probe the plasma in the non-collective scattering regime. The data show that x-ray Thomson scattering enables a complete description of the time-dependent hydrodynamic evolution of shock-compressed CH capsules, with a maximum measured density of ρ > 6 g cm –3 . Additionally, the results demonstrate that accurate measurements of x-ray scattering from bound-free transitions in the CH plasma demonstrate strong evidence that continuum lowering is the primary ionization mechanism of carbon L-shell electrons.

42 ENGINEERING↗
DOE OSTI2013

Synchrotron X-ray measurement techniques for thermal barrier coated cylindrical samples under thermal gradients

Measurement techniques to obtain accurate in situ synchrotron strain measurements of thermal barrier coating systems (TBCs) applied to hollow cylindrical specimens are presented in this work. The Electron Beam Physical Vapor Deposition coated specimens with internal cooling were designed to achieve realistic temperature gradients over the TBC coated material such as that occurring in the turbine blades of aeroengines. Effects of the circular cross section on the x-ray diffraction (XRD) measurements in the various layers, including the thermally grown oxide, are investigated using high-energy synchrotron x-rays. Multiple approaches for beam penetration including collection, tangential, and normal to the layers, along with variations in collection parameters are compared for their ability to attain high-resolution XRD data from the internal layers. This study displays the ability to monitor in situ, the response of the internal layers within the TBC, while implementing a thermal gradient across the thickness of the coated sample. The thermal setup maintained coating surface temperatures in the range of operating conditions, while monitoring the substrate cooling, for a controlled thermal gradient. Through variation in measurement location and beam parameters, sufficient intensities are obtained from the internal layers which can be used for depth resolved strain measurements. Results are used to establish the various techniques for obtaining XRD measurements through multi-layered coating systems and their outcomes will pave the way towards goals in achieving realistic in situ testing of these coatings.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Calibration of an ultra-low-background proportional counter for measuring {sup 37}Ar

An ultra-low-background proportional counter design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electro-chemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with {sup 14}C/{sup 3}H, age-dating of groundwater with {sup 39}Ar, and soil-gas assay for {sup 37}Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of {sup 37}Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of {sup 37}Ar samples over a broad range of proportional counter operating pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for {sup 37}Ar soil gas background studies.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Resolving small signal measurements in experimental plasma environments using calibrated subtraction of noise signals

The performance of many diagnostic and control systems within fusion and other fields of research are often detrimentally affected by spurious noise signals. This is particularly true for those (such as radiation or particle detectors) working with very small signals. Common sources of radiated and conducted noise in experimental fusion environments include the plasma itself and instrumentation. The noise complicates data analysis, as illustrated by noise on signals measured with the heavy ion beam probe (HIBP) installed on the Madison Symmetric Torus. The noise is time-varying and often exceeds the secondary ion beam current (in contrast with previous applications). Analysis of the noise identifies the dominant source as photoelectric emission from the detectors induced by ultraviolet light from the plasma. This has led to the development of a calibrated subtraction technique, which largely removes the undesired temporal noise signals from data. The advantages of the technique for small signal measurement applications are demonstrated through improvements realized on HIBP fluctuation measurements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Measurement of pulsed-power-driven magnetic fields via proton deflectometry

Measuring magnetic field and current distribution in Z-pinch plasma systems is crucial to the validation of Z-pinch theory. In this letter, the demonstration of proton deflectometry to pulsed-power-driven loads at the mega-amp scale is presented, which is capable of making more detailed field maps in high-density regions of plasmas. In this method, a laser-driven, broad-spectrum, MeV-energy proton beam is directed through a pulsed-power-driven plasma system, and the resulting deflections are measured to examine configuration of magnetic fields and to infer the currents that support them. The technique was first demonstrated on simple short-circuit loads, and the results are in excellent agreement with numerical simulations providing reliable estimates of the field and current configurations. It was then applied to a more complex—radial foil—plasma load. The measurements show unexpected proton deflections that exhibit the complexity of the plasma load and that with further analysis will reveal details about the current and magnetic field topology in this complex configuration.

Mariscal, D.↗