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NASA NTRS1980

Upper limits on the power in solar oscillations at 1.2 mm, 9 mm, 3.7 cm, and 11.1 cm wavelengths

A search for solar oscillations has been made using the NRAO 36-ft telescope at 1.2 mm, the NRL 85-ft telescope at 9 mm, and the NRAO four-element interferometer at 3.7 and 11.1 cm wavelengths. After corrections for the small coherence length of the optically observed oscillations, for their known spectral bandwidth, and for the visibility function of the interferometer, upper limits have been placed on the fluctuating power at oscillation frequencies near 3 mHz. The interferometric observations at 3.7 cm and the single-dish observations at 1.2 and 9 mm imply that less than 0.3, 0.04, and 0.1%, respectively, of the bremsstrahlung photons emitted from the chromosphere show periodic fluctuations. This is 1 to 3 orders of magnitude less than the fraction (approximately 1 to 2%) reported at ultraviolet wavelengths. Simple arguments in terms of weak shock theory suggest that the observable oscillations at centimeter and millimeter wavelengths should be intrinsically weaker in the thermal bremmstrahlung radiation than the optical, but the 3.7 cm wavelength results are explained only by the absence of periodic fluctuations at the level of formation.

Kundu, M. R.↗

NASA NTRS2016

Unexpected Nonlinear Effects in Superconducting Transition-Edge Sensors

When a normal metal transitions into the superconducting state the DC resistance drops from a finite value to zero over some finite transition width in temperature, current, and magnetic field. Superconducting transition-edge sensors (TESs) operate within this transition region and uses resistive changes to measure deposited thermal energy. This resistive transition is not perfectly smooth and a wide range of TES designs and materials show sub-structure in the resistive transition (as seen in smooth nonmonotonic behavior, jump discontinuities, and hysteresis in the devices current-voltage relation and derivatives of the resistance with respect to temperature, bias current, and magnetic field). TES technology has advanced to the point where for many applications this structure is the limiting factor in performance and optimization consists of finding operating points away from these structures. For example, operating at or near this structure can lead to nonlinearity in the detectors response and gain scale, limit the spectral range of the detector by limiting the usable resistive range, and degrade energy resolution. The origin of much of this substructure is unknown. This presentation investigates a number of possible sources in turn. First we model the TES as a superconducting weak-link and solve for the characteristic differential equations current and voltage time dependence. We find:(1) measured DC biased current-voltage relationship is the time-average of a much higher frequency limit cycle solution.(2) We calculate the fundamental frequency and estimate the power radiated from the TES treating the bias leads as an antennae.(3) The solution for a set of circuit parameters becomes multivalued leading to current transitions between levels.(4)The circuit parameters can change the measure resistance and mask the true critical current. As a consequence the TES resistance surface is not just a function of temperature, current, and magnetic field but is also a function of the circuit elements (such as shunt resistor, SQUID inductance, and capacitor values). In other words, same device measured in different electrical circuits will have a different resistive surface in temperature, current, and magnetic field. Next we consider that at the transition temperature of a superconductor both the magnetic penetration depth and coherence length are divergent. As a consequence these important characteristic length scales are changing with operating point. We present measurements on devices showing commensurate behavior between these characteristic lengths and the length scale of added normal metal structures. Reordering of proximity vortices leads to discontinuities and irreversibility of the current-voltage curves. Last we consider a weak-link TES including both thermal activated resistance effects and the effect of the magnetic penetration depth being a function of temperature and magnetic field. We derive its impact on the resistive transition surface and the important device parameters a and b.

Superconducting Detectors↗

DOE OSTI2020

Nuclear spin conservation enables state-to-state control of ultracold molecular reactions

Quantum-state control of reactive systems has enabled microscopic probes of underlying interaction potentials and the alteration of reaction rates using quantum statistics. However, extending such control to the quantum states of reaction outcomes remains challenging. Here in this work, we realize this goal by utilizing the conservation of nuclear spins throughout the reaction. Using resonance-enhanced multiphoton ionization spectroscopy to investigate the products formed in bimolecular reactions between ultracold KRb molecules we find that the system retains a near-perfect memory of the reactants’ nuclear spins, manifested as a strong parity preference for the rotational states of the products. We leverage this effect to alter the occupation of these product states by changing the coherent superposition of initial nuclear spin states with an external magnetic field. In this way, we are able to control both the inputs and outputs of a reaction with quantum-state resolution. The techniques demonstrated here open up the possibilities to study quantum entanglement between reaction products, and ultracold reaction dynamics at the state-to-state level.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

NASA NTRS1994

Coherent variations of monthly mean total ozone and lower stratospheric temperature

Space-time patterns of correlation between total ozone and lower stratospheric temperature are documented, based on 14 years (1979-1992) of global monthly mean observations. Data are obtained from the total ozone mapping spectrometer (TOMS) and microwave sounding unit (MSU) channel 4, the latter being a weighted mean temperature of the 150- to 50-mbar layer. These data are analyzed (separately) for linear trend, solar cycle, quasi-biennial oscillation (QBO), and El Nino-Southern Oscillation (ENSO) variations via linear regression: significant signals are identified for each term, and the corresponding structures in ozone and temperature are found to be highly coherent. The temperature trends derived here show significant cooling of the lower stratosphere over Northern Hemisphere (NH) midlatitudes in winter-spring and over Antarctica in Southern Hemisphere (SH) spring; the overall space-time patterns are similar to those determined for ozone trends. Interestingly, temperatures do not decrease over SH midlatitudes during midwinter, in spite of large ozone losses. These data furthermore show globally coherent ozone and temperature perturbations associated with both QBO and ENSO variations; a new result here show large total ozone anomalies in middle-to-high latitudes of both hemispheres associated with ENSO events. Residuals from the ozone and temperature time series (defined as the deseasonalized total minus the regression fits) show strong positive correlation in middle-to-high latitudes but weak correlations in the trop ics. Time periods following the volcanic eruptions of El Chichon and Pinatubo are clearly identified from the coupled signatures of decreased ozone and increased temperature, opposite to the positive ozone-temperature correlations observed at other times. The ratios of ozone to temperature anomalies derived here show quantitative signatures indicating that either radiative (trend, solar, and QBO) or dynamical (ENSO and residuals) processes are responsible for the strong ozone-temperature correlations.

Randel, William J.↗

NASA NTRS1986

Quantum mechanical signature in exclusive coherent pion production

We calculate the coherent production of pions from subthreshold to relativistic energies in heavy-ion collisions using a quantum, microscopic, many-body model. For the first time, in this approach, we use harmonic oscillator wave functions to describe shell-model information. The theoretical quantum mechanical results obtained for the pion spectra represent an important improvement over our previous microscopic, many-body calculations.

NASA Discipline Radiation Health↗

DOE OSTI2025

Single-shot in-line x-ray phase-contrast imaging of void-shockwave interactions in fusion energy materials

Recent breakthroughs in nuclear fusion, specifically the report of reactions exceeding scientific breakeven at the National Ignition Facility (NIF), highlight the potential of inertial fusion energy (IFE) as a sustainable and virtually limitless energy source. However, further progress in IFE requires characterization of defects in ablator materials and how they affect fuel capsule compression. Voids within the ablator can degrade energy yield, but their impact on the density distribution has primarily been studied through simulations, with limited high-resolution experimental validation. To address this, we used the x-ray free-electron laser (XFEL) at the matter in extreme conditions (MECs) instrument at the Linac coherent light source (LCLS) to capture 2D x-ray phase-contrast (XPC) images of a void-bearing sample with a composition similar to inertial confinement fusion (ICF) ablators. By driving a compressive shockwave through the sample using MEC's long-pulse laser system, we analyzed how voids influence shockwave propagation and density distribution during compression. To quantify this impact, we extracted phase information using two phase retrieval algorithms. First, we applied the contrast transfer function (CTF) method, paired with Tikhonov regularization and a fast optimization approach to generate an initial phase estimate. We then refined the result using a projected gradient descent (PGD) method that works directly with the sample's refractive index. Comparing these results with radiation adaptive grid Eulerian (xRAGE) radiation hydrodynamic simulations enables identification of model validation needs or improvements. By calculating phase maps in situ, it becomes possible to reconstruct areal density maps, improving understanding of laser-capsule interactions and advancing IFE research.

Hodge, D. S. [Colorado State Univ., Fort Collins, ↗

DOE OSTI2022

Snowmass Neutrino Frontier NF10 Topical Group Report: Netrino Detectors

We discuss here future neutrino detectors with physics goals ranging from the eV to the EeV scale. The focus is on future enabling technologies for such detectors, rather than existing detectors or those under construction. The report includes methodologies across the broad spectrum of neutrino physics: liquid noble and other cryogenic detectors, including LAr and LXe TPCs; photon-based detectors including technologies enabling hybrid Cherenkov/scintillation detectors; low-threshold detectors which use a wide variety of technologies to probe physics like coherent neutrino-nucleus scattering or detection of cosmic background neutrinos; and ultra-high energy detectors including optical and radio detectors, as well as tracking detectors for use at the forward physics facility of the LHC.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Phasing Magnet for CSX-2 Beamline at NSLS-II

A phasing magnet has been developed at National Synchrotron Light Source II (NSLS-II) for the Coherent Soft X-ray Scattering (CSX) beamline. The phasing magnet will be located at the center of the straight section in between two identical and independent variably polarized APPLE-II devices. Based on Permanent Magnet technology, the phasing magnet has been designed to achieve the required electron beam delay to properly adjust the phase matching of these two consecutive EPUs (Elliptically Polarizing Undulators) and ensure a positive interference between the photon beam emitted in each device. Also this paper will describe the mechanical and magnetic design together with the final field measurements and magnetic tuning results. Also, the spectral performance of the two EPUs and the method used to properly set the field strength of the phasing magnet for any given radiation wavelength and polarization mode will be presented as well.

36 MATERIALS SCIENCE↗

DOE OSTI2022

TNSL support in GNDS 2.0 and beyond [Slides]

This presentation begins by discussing the TNSL format options that went through a major overhaul in GNDS-2.0 and it examines the changes in 2.0. Additionally, it discusses three issues with further changes that should be considered. The first issue is that the project needs some guidance on what to expect when evaluations are performed with coherent inelastic. The second issue is that GNDS-2.0 does not provide a way to clearly specify in the evaluation how to switch to ‘standard’ incident neutron evaluations for energies or temperatures outside the TNSL domain. The third issue is that when GNDS-2.0 was designed, it was assumed that S(α,β) would always be given on a uniform interpolation grid. The presentation concludes by discussing how New JENDL-5 TNSL evaluations have some complications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1995

A search for fast gamma-ray pulsars with OSSE

Pulsar mode data from the Oriented Scintillation Spectrometer Experiment (OSSE) onboard the Compton Gamma Ray Observatory (CGRO), with time resolution between 125 microsecs and 8 ms, have been analyzed for the presence of short-period gamma-ray pulsations. Observations of known point sources (including SN 1987A, SN 1993J, GRO J0422+32, and several pulsars) and of regions where higher densities of pulsars are expected (including the Galactic center, the Galactic plane and arms, and the Large Magellanic Cloud) are included in the study. Both isolated pulsars and pulsars in close binary systems are searched for; in the latter case, the quadratic coherence recovery technique is used to correct for broadening of the pulsar signal from orbital motion. No new gamma-ray pulsars have been detected. Upper limits on the pulsed gamma-ray flux from isolated pulsars in the 50-210 keV energy range of OSSE are between 0.2 x 10(exp -3) and 2.0 x 10(exp -3) photons/s/sq cm for pulse periods between 250 microsecs and 0.5 s. Upper limits on the pulsed flux from binary pulsars are between 1.5 x 10(exp -3) and 6.4 x 10(exp -3) photons/s/sq cm for the same energy band and pulse period range. We estimate that, in the Galaxy, there are fewer than approximately 125 isolated pulsars similar to PSR B1509-58 with radiation peaks in the OSSE band but undetected in the radio and X-rays bands.

Hertz, P.↗

NASA NTRS2018

Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole

Sagittarius A* (Sgr A* ) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the most comprehensive NIR variability data set of Sgr A* to date: eight 24 hr epochs of continuous monitoring of Sgr A* at 4.5 μm with the IRAC instrument on the Spitzer Space Telescope, 93 epochs of 2.18 μm data from Naos Conica at the Very Large Telescope, and 30 epochs of 2.12 μm data from the NIRC2 camera at the Keck Observatory, in total 94,929 measurements. A new approximate Bayesian computation method for fitting the first-order structure function extracts information beyond current fast Fourier transformation (FFT) methods of power spectral density (PSD) estimation. With a combined fit of the data of all three observatories, the characteristic coherence timescale of Sgr A* is b 243 57 82 t = - + minutes (90% credible interval). The PSD has no detectable features on timescales down to 8.5 minutes (95% credible level), which is the ISCO orbital frequency for a dimensionless spin parameter a = 0.92. One light curve measured simultaneously at 2.12 and 4.5 μm during a low flux-density phase gave a spectral index αs = 1.6 ± 0.1 (F µ n s n -a ). This value implies that the Sgr A* NIR color becomes bluer during higher flux-density phases. The probability densities of flux densities of the combined data sets are best fit by log-normal distributions. Based on these distributions, the Sgr A* spectral energy distribution is consistent with synchrotron radiation from a nonthermal electron population from below 20 GHz through the NIR.

accretion↗

DOE OSTI2023

A Consistent Representation of Cloud Overlap and Cloud Subgrid Vertical Heterogeneity

Many global climate models underestimate the cloud cover and overestimate the cloud albedo, especially for low-level clouds. We determine how a correct representation of the vertical structure of clouds can fix part of this bias. We use the 1D McICA framework and focus on low-level clouds. Using Large Eddy Simulations results as reference, we propose a method based on exponential-random overlap that represents the cloud overlap between layers and the subgrid cloud properties over several vertical scales, with a single value of the overlap parameter. Starting from a coarse vertical grid, representative of atmospheric models, this algorithm is used to generate the vertical profile of the cloud fraction with a finer vertical resolution, or to generate it on the coarse grid but with subgrid heterogeneity and cloud overlap that ensures a correct cloud cover. Doing so we find decorrelation lengths are dependent on the vertical resolution, except if the vertical subgrid heterogeneity and interlayer overlap are taken into account coherently. We confirm that the frequently used maximum-random overlap leads to a significant error by underestimating the low-level cloud cover with a relative error of about 50%, that can lead to an error of SW cloud albedo as big as 70%. Not taking into account the subgrid vertical heterogeneity of clouds can cause a relative error of 20% in brightness, assuming the cloud cover is correct.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Homogeneous broadening in the spectrum of a broadband erbium-doped fibre light source

Interference of wave trains separated out in an inhomogeneous emission spectrum of a superluminescent erbium-doped fibre source has been studied by scanning the wavelength of a spectrum analyser. The results demonstrate that, as the spectral resolution of the spectrum analyser decreases to a level corresponding to a sharp drop in interference fringe visibility relative to its original level, near 100 %, fringe visibility becomes dependent on the wavelength in the inhomogeneous spectrum of the source. The reason for this is that, at some characteristic resolution δλ (δλ > 0.5 nm in our case), the coherence time of wave trains is not limited by the spectral resolution of the spectrum analyser and is related to the inhomogeneous spectrum of the source, whose limiting width can be thought of as the homogeneous linewidth in the spectrum of the source. This feature can be used for evaluating homogeneous line broadening. (paper)

74 ATOMIC AND MOLECULAR PHYSICS↗

NASA NTRS1981

Time-resolved spectroscopy of the Mercury 6 3P1 state

The time-resolved fluorescence was observed from the Hg 6 3P1 state under the influence of the earth's magnetic field and with applied fields of up to 14 G. Modulation of the fluorescence decay signal was observed as a function of both time and space and can be interpreted in terms of a classical precession of the excited atom about the magnetic field or as quantum beats resulting from interference between coherently populated Zeeman sublevels. This modulation was studied for each of the five resolvable components of the hyperfine structure separately. The fluorescence from the even isotopes was determined to be almost completely modulated while the fluorescence from the odd isotopes was only partially modulated. The frequency of modulation of the fluorescence from the mercury-202 isotope was observed as a function of the applied magnetic field and a value for the Lande factor of 1.46 + or - 0.03 was obtained. This is within experimental error of the accepted value of 1.486. In addition, the frequency of modulation as a function of applied magnetic field was determined for each of the three resolvable components with more than one contributing isotopic hyperfine line. An investigation of the effect of radiation trapping on the degree modulation was also made.

Halstead, J. A.↗

NASA NTRS2005

Comparison of Different Measurement Technologies for the In-Flight Assessment of Radiated Acoustic Intensity

A series of tests was planned and conducted in the Interior Noise Test Facility at Boeing Field, on the NASA Aries 757 flight research aircraft, and in the Structural Acoustic Loads and Transmission Facility at NASA Langley Research Center. These tests were designed to answer several questions concerning the use of array methods in flight. One focus of the tests was determining whether and to what extent array methods could be used to identify the effects of an acoustical treatment applied to a limited portion of an aircraft fuselage. Another focus of the tests was to verify that the arrays could be used to localize and quantify a known source purposely placed in front of the arrays. Thus the issues related to backside sources and flanking paths present in the complicated sound field were addressed during these tests. These issues were addressed through the use of reference transducers, both accelerometers mounted to the fuselage and microphones in the cabin, that were used to correlate the pressure holograms. measured by the microphone arrays using either SVD methods or partial coherence methods. This correlation analysis accepts only energy that is coherent with the sources sensed by the reference transducers, allowing a noise control engineer to only identify and study those vibratory sources of interest. The remainder of this paper will present a detailed description of the test setups that were used in this test sequence and typical results of the NAH/IBEM analysis used to reconstruct the sound fields. Also, a comparison of data obtained in the laboratory environments and during flights of the 757 aircraft will be made.

Klos, Jacob↗

DOE OSTI2020

Multiscale investigations of europium(III) complexation with tetra- n -octyl diglycolamide confined in porous solid supports

The microscopic, short-range coordination environments and mesoscopic, long-range structures of Eu 3+ contacted with tetra-n-octyl diglycolamide (TODGA) confined on ordered mesoporous carbon (OMC) nanoparticles and Amberchrom CG 71 resin were probed using Eu L 3 -edge extended X ray absorption fine structure (EXAFS) as well as small-angle and wide-angle X ray scattering, SAXS and WAXS, respectively. A homoleptic Eu(TODGA) 3 3+ coordination complex typical of liquid-liquid extraction (LLE) chemistry is present under low Eu 3+ loading conditions on both solid supports. Deviations from this traditional structure motif appear at hyperstoichiometric Eu 3+ loadings, above the 1:3 Eu 3+ to TODGA mole ratio. Microcrystalline-like domains with multinuclear Eu speciation are templated by use of these high Eu 3+ loading conditions with the functionalized OMC materials, highlighting a major departure of liquid-solid extraction chromatography (EXC) from the coordination chemistry of LLE. No such long-range spatial coherence was observed for analogous polyacrylic resin materials. Furthermore, these results demonstrate both the similarities and differences between multiscale structures in LLE and EXC, underscoring the opportunities for improved separation techniques based on solid supports with long-range spatial coherence (e.g., OMC systems) and without it (e.g., resin materials). Since crystallization was the first approach to adjacent lanthanide separations, the prospect of templating microcrystalline TODGA-lanthanide complexes that are otherwise not prone to crystallization by use of OMC nanoparticles represents a new entry to addressing long-standing issues in purification by liquid-solid phase separation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Old neutron stars as a new probe of relic neutrinos and sterile neutrino dark matter

We study the kinetic cooling (heating) of old neutron stars due to coherent scattering with relic neutrinos (sterile neutrino dark matter) via Standard Model neutral-current interactions. We take into account several important physical effects, such as coherent enhancement, gravitational clustering, neutron degeneracy, Pauli blocking and weak potential. We find that the anomalous cooling of neutron stars due to relic neutrino scattering is difficult to observe. However, the anomalous heating of neutron stars due to coherent scattering with keV-scale sterile neutrino dark matter may be observed by current and future telescopes operating in the optical to near-infrared frequency band, such as the James Webb Space Telescope (JWST), which would probe hitherto unexplored parameter space in the sterile neutrino mass-mixing plane. Published by the American Physical Society 2025

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1994

Measurements of anisotropy in the cosmic microwave background radiation at 0.5 deg angular scales near the star gamma ursae minoris

We present results from a four-frequency observation of a 6 deg x 0.6 deg strip of the sky centered near the star Gamma Ursae Minoris (GUM) during the fourth flight of the Millimeter-wave Anistropy experiment(MAX). The observation was made with a 1.4 deg peak-to-peak sinusoidal chop in all bands. The FWHM beam sizes were 0.55 deg +/- 0.05 deg at 3.5 per cm and 0.75 deg +/- 0.05 deg at 6, 9, and 14 per cm. During this observation significant correlated structure was observed at 3.5, 6 and 9 per cm with amplitudes similar to those observed in the GUM region during the second and third fligts of MAX. The frequency spectrum is consistent with cosmic microwave background (CMB) and inconsistent with thermal emission from interstellar dust. The extrapolated amplitudes of synchrotron and free-free emission are too small to account for the amplitude of the observed structure, If all of the structure is attributed to CMB anisotropy with a Gaussian autocorrelation function and a coherence angle of 25 min, then the most probable values of delta T/T(sub CMB) in the 3.5, 6 and 9 per cm bads are (4.3 +2.7/-1.6) x 10(exp -5), 2.8 (+4.3/-1/1) x 10(exp -5), and 3.5 (+3.0/-1.6) x 10(exp -5) (95% confidence upper and lower limits), respectively.

Devlin, M. J.↗