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DOE OSTI2018

Thermo Raw File Reader

The Thermo Raw File Reader is a .NET DLL wrapper for Thermo's MS File Reader, which is accessible by creating an account at https://thermo.flexnetoperations.com/control/thmo/login then logging in and choosing "Utility Software". The Thermo Raw File Reader DLL provides several methods for parsing the information returned by MSFileReader, including: Determining the parent ion m/z and fragmentation mode in a given scan filter, determining the Ionization mode from a given scan filter, extracting MRM masses listed in a given scan filter, reporting the number of spectra in the .Raw file, returning details on a specific spectrum, and Obtaining the raw m/z and intensity values for a given spectrum.

Gibbons, Bryson↗

DOE OSTI2013

Annual Report FY2013-- A Kinematically Complete, Interdisciplinary, and Co-Institutional Measurement of the 19F(α,n) Cross-section for Nuclear Safeguards Science

The goal of this proposal is to enable neutron detection for precision Non-Destructive Assays (NDAs) of actinide-fluoride samples. Neutrons are continuously generated from a UFx matrix in a container or sample as a result of the interaction of alpha particles from uranium-decay α particles with fluorine nuclei in the matrix. Neutrons from 19F(α,n)22Na were once considered a poorly characterized background for assays of UFx samples via 238U spontaneous fission neutron detection [SMI2010B]. However, the yield of decay-α-driven neutrons is critical for 234,235U LEU and HEU assays, as it can used to determine both the total amount of uranium and the enrichment [BER2010]. This approach can be extremely valuable in a variety of safeguard applications, such as cylinder monitoring in underground uranium storage facilities, nuclear criticality safety studies, nuclear materials accounting, and other nonproliferation applications. The success of neutron-based assays critically depends on an accurate knowledge of the cross section of the (α,n) reaction that generates the neutrons. The 40% uncertainty in the 19F(α,n)22Na cross section currently limits the precision of such assays, and has been identified as a key factor in preventing accurate enrichment determinations [CRO2003]. The need for higher quality cross section data for (α,n) reactions has been a recurring conclusion in reviews of the nuclear data needs to support safeguards. The overarching goal of this project is to enable neutron detection to be used for precision Non- Destructive Assays (NDAs) of actinide-fluoride samples. This will significantly advance safeguards verification at existing declared facilities, nuclear materials accounting, process control, nuclear criticality safety monitoring, and a variety of other nonproliferation applications. To reach this goal, Idaho National Laboratory (INL), in partnership with Oak Ridge National Laboratory (ORNL), Rutgers University (RU), and the University of Notre Dame (UND), will focus on three specific items: (1) making a precision (better than 10 %) determination of the absolute cross section of the 19F(α,n)22Na reaction as a function of energy; (2) determining the spectrum of neutrons and γ-rays emitted from 19F(α,n)22Na over an energy range pertinent to NDA; and (3) performing simulations with this new cross section to extract the neutron yield (neutrons/gram/second) and resulting neutron- and gamma ray-spectra when α particles interact with fluorine nuclei in actinide samples, to aid in the design and reduce uncertainty of future NDA measurements and simulations.

VANDLE, HPGe gamma-ray detector, liquid neutron de↗

DOE OSTI2021

Transmission Spectroscopy for the Warm Sub-Neptune HD 3167c: Evidence for Molecular Absorption and a Possible High-metallicity Atmosphere

We present a transmission spectrum for the warm (500−600 K) sub-Neptune HD 3167c obtained using the Hubble Space Telescope Wide Field Camera 3 infrared spectrograph. We combine these data, which span the 1.125–1.643 μm wavelength range, with broadband transit measurements made using Kepler/K2 (0.6–0.9 μm) and Spitzer/IRAC (4–5 μm). We find evidence for absorption by at least one of H{sub 2}O, HCN, CO{sub 2}, and CH{sub 4} (Bayes factor 7.4; 2.5σ significance), although the data precision does not allow us to unambiguously discriminate between these molecules. The transmission spectrum rules out cloud-free hydrogen-dominated atmospheres with metallicities ≤100× solar at >5.8σ confidence. In contrast, good agreement with the data is obtained for cloud-free models assuming metallicities >700× solar. However, for retrieval analyses that include the effect of clouds, a much broader range of metallicities (including subsolar) is consistent with the data, due to the degeneracy with cloud-top pressure. Self-consistent chemistry models that account for photochemistry and vertical mixing are presented for the atmosphere of HD 3167c. The predictions of these models are broadly consistent with our abundance constraints, although this is primarily due to the large uncertainties on the latter. Interior structure models suggest that the core mass fraction is >40%, independent of a rock or water core composition, and independent of atmospheric envelope metallicity up to 1000× solar. We also report abundance measurements for 15 elements in the host star, showing that it has a very nearly solar composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

Nebular Continuum and Line Emission in Stellar Population Synthesis Models

Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emissions can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on H α , and physical properties derived from broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H ii regions and star-forming galaxies. Our models show improved agreement with the observed H ii regions in the Ne iii/O ii plane and show satisfactory agreement with He ii emission from z = 2 galaxies, when including rotating stellar models. Models including post-asymptotic giant branch stars are able to reproduce line ratios consistent with low-ionization emission regions. The models are integrated into current versions of FSPS and include self-consistent nebular emission predictions for MIST and Padova+Geneva evolutionary tracks.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Toward Interpreting the IBEX Ribbon with Mirror Diffusion in Interstellar Turbulent Magnetic Fields

We investigate the role of the magnetohydrodynamic (MHD) turbulence measured by Voyager in the very local interstellar medium (VLISM) in modeling the Interstellar Boundary Explorer ribbon. We demonstrate that the mirroring by compressible modes of MHD turbulence dominates over that by the mean magnetic field. Based on the new mirror diffusion mechanism identified by Lazarian & Xu for particles with large pitch angles in MHD turbulence, we find that the mirror diffusion can both confine pickup ions and preserve their initial pitch angles, and thus it accounts for the enhanced intensity of energetic neutral atoms that return to the heliosphere. The ribbon width is determined by both the range of pitch angles for effective turbulent mirroring and the field line wandering induced by Alfvénic modes. It in turn provides a constraint on the amplitude of magnetic fluctuations of fast modes. The field line wandering also affects the coherence of the ribbon structure across the sky. By extrapolating the magnetic energy spectrum measured by Voyager, we find that the injection scale of the turbulence in the VLISM must be less than ~500 au for the ribbon structure to be coherent.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1981

Acceleration theory for 5-40 keV ions at interplanetary shocks

A theory is presented to explain the acceleration of suprathermal ions observed near propagating shocks in the solar wind. The hard power-law spectra of ions of energies 5 to 40 keV are shown to be accounted for by diffusive scattering across a plane shock with a small amount of adiabatic deceleration losses on both sides of the shock. The theory fits the observations of the event of November 25, 1977, which followed a large solar flare, and indicates a mean free path perpendicular to the shock of less than 0.0003 AU behind the shock and 0.01 AU in front of it. The theory also predicts a steepening ion energy spectrum at higher energies.

Forman, M. A.↗

NASA NTRS2002

Large Torque Variations in Two Soft Gamma Repeaters

We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of approximately 4, which persist for several months. Using long-baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR (Soft Gamma Repeater). The power spectrum of each source is very red (power-law slope is approximately -3.5). The torque noise power levels are consistent with some accreting systems on timescales of approximately 1 yr, yet the full power spectrum is much steeper in frequency than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have been seen only in young, glitching radio pulsars (e.g., Vela). The observed changes in spin-down rate do not correlate with burst activity; therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity can not account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.

Woods, Peter M.↗

NASA NTRS2002

How Do The Relativistic Effects Effect the Appearance of a Clothed Black Hole?

For an accretion disk around a black hole, the strong relativistic effects affect every aspect of the radiation from the disk, including the spectrum, the light-curve, and the image. If the disk is in high inclination angle (nearly edge-on), the image will be greatly distorted; the farther side of the disk will appear to bend toward the observer, photons from the other side of the disk can reach the observer (if they are not blocked by the disk) to form a ghost image. This work differs mainly from previous work by taking into account the temperature distribution of a standard thin disk model and investigating the expected images from different viewing angles and in different energy bands. The edge-blocking effect is also considered. Direct images of black hole systems may be obtained with future X-ray missions like MAXIM pathfinder.

Zhang, Xiaoling↗

NASA NTRS2014

A Framework for Modelling Connective Tissue Changes in VIIP Syndrome

Insertion of astronauts into microgravity induces a cascade of physiological adaptations, notably including a cephalad fluid shift. Longer-duration flights carry an increased risk of developing Visual Impairment and Intracranial Pressure (VIIP) syndrome, a spectrum of ophthalmic changes including posterior globe flattening, choroidal folds, distension of the optic nerve sheath, kinking of the optic nerve and potentially permanent degradation of visual function. The slow onset of changes in VIIP, their chronic nature, and the similarity of certain clinical features of VIIP to ophthalmic findings in patients with raised intracranial pressure strongly suggest that: (i) biomechanical factors play a role in VIIP, and (ii) connective tissue remodeling must be accounted for if we wish to understand the pathology of VIIP. Our goal is to elucidate the pathophysiology of VIIP and suggest countermeasures based on biomechanical modeling of ocular tissues, suitably informed by experimental data, and followed by validation and verification. We specifically seek to understand the quasi-homeostatic state that evolves over weeks to months in space, during which ocular tissue remodeling occurs. This effort is informed by three bodies of work: (i) modeling of cephalad fluid shifts; (ii) modeling of ophthalmic tissue biomechanics in glaucoma; and (iii) modeling of connective tissue changes in response to biomechanical loading.

microgravity↗

DOE OSTI2018

Inference of the electron temperature in inertial confinement fusion implosions from the hard X-ray spectral continuum

Using the free-free continuum self-emission spectrum at photon energies above 15 keV is one of the most promising concepts for assessing the electron temperature in inertial confinement fusion (ICF) experiments. However, these photons are due to suprathermal electrons whose mean free path is much larger than the thermal one, making their distribution deviate from Maxwellian in a finite-size hotspot. Here, the first study of the free-free X-ray emission from an ICF implosion is conducted, accounting for the kinetic modifications to the electron distribution. These modifications are found to result in qualitatively new features in the hard X-ray spectral continuum. Finally, inference of the electron temperature as if the emitting electrons are Maxwellian is shown to give a lower value than the actual one.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2014

On velocity and reactive scalar spectra in turbulent premixed flames

Abstract Kinetic energy and reactive scalar spectra in turbulent premixed flames are studied from compressible three-dimensional direct numerical simulations (DNS) of a temporally evolving rectangular slot-jet premixed flame, a statistically one-dimensional configuration. The flames correlate to a lean premixed hydrogen–air mixture at an equivalence ratio of 0.7, preheated to 700 K and at 1 atm, and three DNS are considered with a fixed jet Reynolds number of 10 000 and a jet Damköhler number varying between 0.13 and 0.54. For the study of spectra, motivated by the need to account for density change, which can be locally strong in premixed flames, a new density-weighted definition for two-point velocity/scalar correlations is proposed. The density-weighted two-point correlation tensor retains the essential properties of its constant-density (incompressible) counterpart and recovers the density-weighted Reynolds stress tensor in the limit of zero separation. The density weighting also allows the derivation of balance equations for velocity and scalar spectrum functions in the wavenumber space that illuminate physics unique to combusting flows. Pressure–dilatation correlation is a source of kinetic energy at high wavenumbers and, analogously, reaction rate–scalar fluctuation correlation is a high-wavenumber source of scalar energy. These results are verified by the spectra constructed from the DNS data. The kinetic energy spectra show a distinct inertial range with a $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}-5/3$ scaling followed by a ‘diffusive–reactive’ range at higher wavenumbers. The exponential drop-off in this range shows a distinct inflection in the vicinity of the wavenumber corresponding to a laminar flame thickness, $\delta _L$ , and this is attributed to the contribution from the pressure–dilatation term in the energy balance in wavenumber space. Similarly, a clear spike in spectra of major reactant species (hydrogen) arising from the reaction-rate term is observed at wavenumbers close to $\delta _L$ . It appears that in the inertial range classical scaling laws for the spectra involving the Kolmogorov scale are applicable, but in the high-wavenumber range where chemical reactions have a strong signature the laminar flame thickness produces a better collapse. It is indicated that a full scaling should perhaps involve the Kolmogorov scale, laminar flame thickness, Damköhler number and Karlovitz number.

42 ENGINEERING↗

DOE OSTI2018

On the Usage of Ultrasound Computational Models for Decision Making Under Ambiguity

Computer modeling and simulation is becoming pervasive within the non-destructive evaluation (NDE) industry as a convenient tool for designing and assessing inspection techniques. This raises a pressing need for developing quantitative techniques for demonstrating the validity and applicability of the computational models. Computational models provide deterministic results based on deterministic and well-defined input, or stochastic results based on inputs defined by probability distributions. However, computational models cannot account for the effects of personnel, procedures, and equipment, resulting in ambiguity about the efficacy of inspections based on guidance from computational models only. In addition ambiguity arises when model inputs, such as the representation of realistic cracks, cannot be defined deterministically, probabilistically, or by intervals. In this work, Pacific Northwest National Laboratory demonstrates the ability of computational models to represent field measurements under known variabilities, and quantify the differences using maximum amplitude and power spectrum density metrics. Sensitivity studies are also conducted to quantify the effects of different input parameters on the simulation results.

Dib, Gerges↗

DOE OSTI2015

HATS-6b: A WARM SATURN TRANSITING AN EARLY M DWARF STAR, AND A SET OF EMPIRICAL RELATIONS FOR CHARACTERIZING K AND M DWARF PLANET HOSTS

We report the discovery by the HATSouth survey of HATS-6b, an extrasolar planet transiting a V = 15.2 mag, i = 13.7 mag M1V star with a mass of 0.57 M{sub ⊙} and a radius of 0.57 R{sub ⊙}. HATS-6b has a period of P = 3.3253 d, mass of M{sub p} = 0.32 M{sub J}, radius of R{sub p} = 1.00 R{sub J}, and zero-albedo equilibrium temperature of T{sub eq} = 712.8 ± 5.1 K. HATS-6 is one of the lowest mass stars known to host a close-in gas giant planet, and its transits are among the deepest of any known transiting planet system. We discuss the follow-up opportunities afforded by this system, noting that despite the faintness of the host star, it is expected to have the highest K-band S/N transmission spectrum among known gas giant planets with T{sub eq}<750 K. In order to characterize the star we present a new set of empirical relations between the density, radius, mass, bolometric magnitude, and V-, J-, H- and K-band bolometric corrections for main sequence stars with M<0.80 M{sub ⊙}, or spectral types later than K5. These relations are calibrated using eclipsing binary components as well as members of resolved binary systems. We account for intrinsic scatter in the relations in a self-consistent manner. We show that from the transit-based stellar density alone it is possible to measure the mass and radius of a ∼0.6 M{sub ⊙} star to ∼7 and ∼2% precision, respectively. Incorporating additional information, such as the V−K color, or an absolute magnitude, allows the precision to be improved by up to a factor of two.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2021

Neutron scattering study of magnetic anisotropy in the tetragonal antiferromagnet Bi 2 CuO 4

In this work, we present a comprehensive study of magnon excitations in the tetragonal easy-plane antiferromagnet Bi 2 CuO 4 using inelastic neutron scattering and spin-wave analyses. The nature of low-energy magnons, and hence the anisotropy in this material, has been controversial. We show unambiguously that the low-energy magnon spectrum consists of a gapped and a gapless mode, which we attribute to out-of-plane and in-plane spin fluctuations, respectively. We modeled the observed magnon spectrum using linear spin-wave analysis of a minimal anisotropic spin model motivated by the lattice symmetry. By studying the magnetic field dependence of the (1,0,0) Bragg peak intensity and the in-plane magnon intensity, we observed a spin-flop transition in the ab plane at ~0.4 T, which directly indicates the existence of a small in-plane anisotropy that is classically forbidden. It is only by taking into account magnon zero-point fluctuations beyond the linear spin-wave approximation that we could explain this in-plane anisotropy and its magnitude, the latter of which is deduced from the critical field of the spin-flop transition. The microscopic origins of the observed anisotropic interactions are also discussed. We found that our data are inconsistent with a large Dzyaloshinskii-Moriya interaction, which suggests a potential departure of Bi 2 CuO 4 from the conventional theories of magnetic anisotropy for other cuprates.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2016

TH-CD-201-04: A Study of Cherenkov Light Generated and Collected in Plastic Scintillation Detector

Purpose: To study Cherenkov light emission in plastic scintillation detectors (PSDs) from a theoretical point of view to identify situations that may arise where the calibration coefficient obtained in one condition is not applicable to another condition. By identifying problematic situations, we hope to provide guidance on how to confidently use PSDs. Methods: Cherenkov light emission in PSD was modelled using basic physical principles. In particular, changes in refractive index as a function of wavelength were accounted for using the Sellmeier empirical equation. Both electron and photon beams were considered. For photons, realistic distributions of secondary charged particles were calculated using Klein-Nishina’s formula. Cherenkov production and collection in PSDs were studied for a range of parameters including beam energy, charged particle momentum distribution, detector orientation and material composition. Finally, experimental validation was made using a commercial plastic scintillation detector. Results: In specific situations, results show that the Cherenkov spectrum coupled in the PSD can deviate from its expected behaviour (i.e. one over the square of the wavelength). In these cases were the model is realistic it is possible to see a peak wavelength instead of a monotonically decreasing function. Consequences of this phenomenon are negligible when the momentum of charged particle is distributed randomly, but in some clinically relevant cases, such as an electron beam at depth close to R50 or for photon beams with minimal scatter component, the value of the calibration coefficient can be altered. Experimental tests with electron beams showed changes in the Cherenkov light ratio, the parameter used in the calibration of PSDs, up to 2–3% depending on the PSD orientation. Conclusion: This work is the first providing a physical explanation for apparent change in PSD calibration coefficient. With this new information at hand, it will be possible to better guide the clinical use of PSDs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2017

Explicit Form of the Radiative and Collisional Branching Ratios in Polarized Radiation Transport with Coherent Scattering

We consider the vector emissivity of the polarized radiation transfer in a Λ-type atomic transition, which we recently proposed to account for both complete frequency redistribution (CRD) and partial redistribution (PRD) contributions to the scattered radiation. This expression can concisely be written as ε = ( ε ( 1 ) − ε f . s . ( 2 ) ) + ε ( 2 ) , where ε{sup (1)} and ε{sup (2)} are the emissivity terms describing, respectively, one-photon and two-photon processes in a Λ-type atom, and where “f.s.” means that the corresponding term must be evaluated assuming an appropriate “flat spectrum” average of the incident radiation across the spectral line. In this follow-up study, we explicitly consider the expressions of these various terms for the case of a polarized multi-term atom to derive the algebraic forms of the branching ratios between the CRD and PRD contributions to the emissivity. In the limit of a two-term atom with non-coherent lower term, our results are shown to be in full agreement with those recently derived by Bommier.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1990

Acceleration, transport of and radiation by electrons in impulsive phase of flares

Recent work carried out in connection with various manifestations of the impulsive phase of solar flares is reviewed. Characteristics of accelerated electrons are determined, taking into account various possible interactions that electrons undergo as they traverse the flare plasma, and the expected radiation is evaluated via several mechanisms. Constraints are set on the characteristics of the accelerated electrons and on some properties of the flare plasma. Results obtained from comparisons with SMM and other observations of flares during the past solar cycle are described. It is shown that limits can be set on the range and distribution of the accelerated electron spectrum and pitch angle distribution, and on the column depth and field convergence rate of the flaring loop.

Petrosian, Vahe↗

DOE OSTI2026

Real-time estimators for scattering observables: A full account of finite-volume errors for quantum simulation

The real-time correlators of quantum field theories can be directly probed through new approaches to simulation, such as quantum computing and tensor networks. This provides a new framework for computing scattering observables in lattice formulations of strongly interacting theories, such as lattice quantum chromodynamics. In this paper, we prove that the proposal of real-time estimators of scattering observables is universally applicable to all scattering observables of gapped quantum field theories. All finite-volume errors are exponentially suppressed, and the rate of this suppression is controlled by the regulator considered, namely, a displacement of the spectrum of the theory into the complex plane. A partial restoration of Lorentz symmetry by averaging over different boosts gives an additional suppression of finite volume errors. Our results also apply to the simulation of wave packet scattering, where a similar averaging is performed to construct the wave packets that regulate the finite volume effects. This result represents a necessary key step toward determining a broad class of scattering observables via quantum computing that are currently inaccessible via classical computing. Such observables are relevant for various applications, including hadron spectroscopy, hadron structure, and precision tests of the Standard Model. We also comment on potential applications of our results to traditional computational schemes.

Burbano, Ivan M. [University of California, Berkel↗