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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Search for an Anomalous Excess of Single Photons in the MicroBooNE Neutrino Experiment

Neutrinos are some of the most elusive particles in the standard model, being incredibly common throughout the universe, but interacting with detectors incredibly rarely. Certain properties of neutrinos remain difficult to measure, including their masses, their CP violation properties, and whether or not they are their own antiparticles. Additionally, there have been several anomalous results in neutrino experiments which remain unexplained. MicroBooNE was built in order to study these anomalous results using a more capable detector technology, the Liquid Argon Time Projection Chamber. Specifically, MicroBooNE is able to search for an anomalous excess of low energy electromagnetic showers, which was previously observed by the MiniBooNE experiment. In particular, MicroBooNE is able to study whether the excess could consist of electron showers or photon showers. In this thesis, I describe a search for this anomalous excess by targeting neutral current Delta radiative decays, the largest expected source of single photons in MicroBooNE. We observe data consistent with our nominal expectation, but cannot rule out all potential sources of additional single photon events, particularly those with no visible proton activity. There remains significant potential to probe this channel in even more detail using MicroBooNE and other experiments in the near future.Hagaman, Lee

Hagaman, Lee [Chicago U.]↗
NASA NTRS1988

Monolithic electro-optic modulator array

A PIN GaAlAs diode structure is provided with parameters for index guiding of light in a single mode. The index of refraction of the central layer I (which in practice may be lightly doped .pi. or .nu.) is greater than the p- and n-layers to create a slab waveguide in the transverse direction. Stripe contacts define separate waveguide channels that are separated electrically and optically by implanting protons or etching grooves between the stripe contacts in the upper layer. Separate reverse biasing voltages may be applied to the stripe contacts for modulation of the light in proportions to the voltage, either with absorption modulation, if the light wavelength is within about 500.ANG. of the bandgap of the .pi.-material, or phase-delay modulation, if the wavelength is separated from the bandgap of the .pi.-material by at least 900.ANG..

Robinson, Deborah L.↗
NASA NTRSDate not supplied

ELMO: ELectron Microburst Observatory Mission to Study Microbursts

We describe the ELectron Microburst Observatory mission, ELMO which is proposed as a CubeSat constellation mission to fully characterize microburst event spatial extent systematically for the first time both in latitude and longitude. ELMO comprises 4 CubeSats two per orbit plane in two orbit planes. ELMO will fly in a high inclination LEO at about 500 km in altitude. The CubeSats will systematically separate both in latitude and longitude over the mission lifetime and will carry MERIT, Miniaturized Electron and Proton Telescope as the the payload. MERIT has been built,tested and delivered to fly on NASA's HERMES, Lunar Gateway mission. MERIT is a solid state detector particle telescope with two identical sensor heads pointed zenith- and nadir-wards enabling measurement of both downgpoing and upwelling electrons thereby accurately estimating electron precipitation into the atmosphere. MERIT will measure electron and protons over a wide energy range in multiple differential channels with a very time resolution of less than 4 ELMO will quantify for the first time the contribution of microbursts to radiation belt electron loss using systematic coordinated multipoint measurements. Energetic electron precipitation affects atmospheric chemistry and therefore climate change. ELMO measures microbursts with unprecedented time and energy resolution. ELMO provides critical knowledge of electron loss processes required for quantitative prediction of global electron fluxes.

Shri Kanekal↗
NASA NTRS2000

The Proton and Electron Aurora as Seen by Image-FUV and FAST

The Far Ultraviolet (FUV) instrument on IMAGE images the aurora in three different wavelength regions. The Wideband Imaging Camera (WIC) observes the molecular Lyman-Birge-Hopfield (LBH) and atomic Nitrogen emissions at 140-190 nm. The two channels of the Spectrographic Imager (SI) observe the Doppler shifted Lyman Alpha emission of precipitating protons at 121.8 nm (SI 12) and the mostly electron produced emission from oxygen OI at 135.6 nm (SI13). The major advantage of FUV compared to previously flown UV imagers is the simultaneous operation of all three imaging systems without the need for filter changes and the uncertainty of temporal changes of the aurora between exposures. The FAST satellite passes every two hours through FUV images during apogee operations. This enables a comparison between the remotely imaged particle precipitation and the in-situ measurements along the FAST track. The detailed analysis of images from all three systems together with a full simulation of auroral emissions based on in-situ measurements by FAST confirms the laboratory calibrations of FUV. The spatial resolution and image quality of WIC permits the observation of a good correspondence between in-situ and remote measurements of precipitation boundaries. The clear separation between the lower latitude proton precipitation and the more structured higher latitude electron precipitation is obtained with both SI-channels.

Gerard, J.-C.↗
DOE OSTI2025

Measurement of single- and double-differential cross sections for mesonless charged-current muon neutrino interactions on argon with final-state protons using the MicroBooNE detector

Charged-current neutrino interactions with final states containing zero mesons and at least one proton are of high interest for current and future accelerator-based neutrino oscillation experiments. Using the Booster Neutrino Beam and the MicroBooNE detector at Fermi National Accelerator Laboratory, we have obtained the first double-differential cross-section measurements of this channel for muon neutrino scattering on an argon target with a leading proton momentum threshold of 0.25 GeV/𝑐. We also report a flux-averaged total cross section of 𝜎 = (11.8±1.2) × 10 −38 cm 2 /Ar and several single-differential measurements which extend and improve upon previous results. Statistical and systematic uncertainties are quantified with a full treatment of correlations across 359 kinematic bins, including correlations between distributions describing different observables. The resulting dataset provides the most detailed information obtained to date for testing models of mesonless neutrino-argon scattering.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Molecular-Level Control over Ionic Conduction and Ionic Current Direction by Designing Macrocycle-Based Ionomers

Poor ionic conductivity of the catalyst-binding, submicrometer- thick ionomer layers in energy conversion and storage devices is a huge challenge. However, ionomers are rarely designed keeping in mind the specific issues associated with nanoconfinement. Here, we designed nature-inspired ionomers (calix-2) having hollow, macrocyclic, calix[4]arene-based repeat units with precise, sub-nanometer diameter. In ≤100 nm-thick films, the in-plane proton conductivity of calix-2 was up to 8 times higher than the current benchmark ionomer Nafion at 85% relative humidity (RH), while it was 1-2 orders of magnitude higher than Nafion at 20-25% RH. Confocal laser scanning microscopy and other synthetic techniques allowed us to demonstrate the role of macrocyclic cavities in boosting the proton conductivity. The systematic self-assembly of calix-2 chains into ellipsoids in thin films was evidenced from atomic force microscopy and grazing incidence small-angle X-ray scattering measurements. Moreover, the likelihood of alignment and stacking of macrocyclic units, the presence of one-dimensional water wires across this macrocycle stacks, and thus the formation of long-range proton conduction pathways were suggested by atomistic simulations. We not only did see an unprecedented improvement in thin-film proton conductivity but also saw an improvement in proton conductivity of bulk membranes when calix-2 was added to the Nafion matrices. Nafion-calix-2 composite membranes also took advantage of the asymmetric charge distribution across calix[4]arene repeat units collectively and exhibited voltage-gating behavior. The inclusion of molecular macrocyclic cavities into the ionomer chemical structure can thus emerge as a promising design concept for highly efficient ion-conducting and ion-permselective materials for sustainable energy applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1993

A radiation belt monitor for the High Energy Transient Experiment Satellite

A Radiation Belt Monitor (RBM) sensitive to protons and electrons with energy approximately greater than 0.5 MeV has been designed for the High Energy Transient Experiment (HETE) satellite in order to: first, control the on-off configuration of the experiments (i.e. those susceptible to proton damage); and second, to indicate the presence of proton and/or electron events that could masquerade as legitimate high energy photon events. One of the two RBM channels has an enhanced sensitivity to electrons. Each channel of the RBM, based on a PIN silicon diode, requires a typical power of 6 milliwatts. Tests have been performed with protons with energies from approximately 0.1 to 2.5 MeV (generated by a Cockcroft-Walton linear accelerator via the d(d,p)t reaction), and with electrons with energies up to 1 MeV (from a 1.0 microcurie Bi-207 source).

Lo, D. H.↗
DOE OSTI2023

Hexadecapole strength in the rare isotopes 74,76 Kr

In the Ge-Sr mass region, isotopes with neutron number N ≤ 40 are known to feature rapid shape changes with both nucleon number and angular momentum. To gain new insights into their structure, inelastic proton scattering experiments in inverse kinematics were performed on the rare isotopes 74,76 Kr. This work focuses on observables related to the J π = $4$$^{+}_{1}$ states of the Kr isotopes and, in particular, on the hexadecapole degree of freedom. By performing coupled-channels calculations, hexadecapole deformation parameters β 4 were determined for the J π = $4$$^{+}_{1}$ states of 74,76 Kr from inelastic proton scattering cross sections. Two possible coupled-channels solutions were found. A comparison to predictions from nuclear energy density functional theory, employing both non-relativistic and relativistic functionals, clearly favors the large, positive β 4 solutions. These β 4 values are unambiguously linked to the well deformed prolate configuration. Given the β 2 - β 4 trend, established in this work, it appears that β 4 values could provide a sensitive measure of the nuclear shell structure.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Observation of the ϒ ( 3 S ) Meson and Suppression of ϒ States in Pb-Pb Collisions at s N N = 5.02 TeV

The production of ϒ ( 2 S ) and ϒ ( 3 S ) mesons in lead-lead (Pb-Pb) and proton-proton ( p p ) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The ϒ ( 3 S ) meson is observed for the first time in Pb-Pb collisions, with a significance above 5 standard deviations. The ratios of yields measured in Pb-Pb and p p collisions are reported for both the ϒ ( 2 S ) and ϒ ( 3 S ) mesons, as functions of transverse momentum and Pb-Pb collision centrality. These ratios, when appropriately scaled, are significantly less than unity, indicating a suppression of ϒ yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for ϒ ( 3 S ) mesons compared to ϒ ( 2 S ) mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the J / ψ , ψ ( 2 S ) , ϒ ( 1 S ) , and ϒ ( 2 S ) mesons. © 2024 CERN, for the CMS Collaboration 2024 CERN

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Higgs boson production cross-section measurements and their EFT interpretation in the $4\ell $ decay channel at $\sqrt{s}=$13 TeV with the ATLAS detector

Higgs boson properties are studied in the four-lepton decay channel (where lepton = e, μ) using 139 fb -1 of proton–proton collision data recorded at $\sqrt{s}=$13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio for H→ZZ* decay is measured to be 1.34±0.12 pb for a Higgs boson with absolute rapidity below 2.5, in good agreement with the Standard Model prediction of 1.33±0.08 pb. Cross-sections times branching ratio are measured for the main Higgs boson production modes in several exclusive phase-space regions. The measurements are interpreted in terms of coupling modifiers and of the tensor structure of Higgs boson interactions using an effective field theory approach. Exclusion limits are set on the CP-even and CP-odd ‘beyond the Standard Model’ couplings of the Higgs boson to vector bosons, gluons and top quarks.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Measurement of the associated production of a top-antitop-quark pair and a Higgs boson decaying into a $b\bar{b}$ pair in pp collisions at $\sqrt{s} = 13$ TeV using the ATLAS detector at the LHC

This paper reports the measurement of Higgs boson production in association with a $t\bar{t}$ pair in the $H$ → $b\bar{b}$ decay channel. The analysis uses 140 fb -1 of 13 TeV proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider. The final states with one or two electrons or muons are employed. An excess of events over the expected background is found with an observed (expected) significance of 4.6 (5.4) standard deviations. The $t\bar{t}$ $H$ cross-section is $σ_{t\bar{t} H}$ = $411^{+101}_{-92}$ fb = $411 ± 54$ (stat.) $^{+85}_{-75}$ (syst.) fb for a Higgs boson mass of 125.09 GeV, consistent with the prediction of the Standard Model of $507^{+35}_{-75}$ fb. The cross-section is also measured differentially in bins of the Higgs boson transverse momentum within the simplified template cross-section framework.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1994

The continuum spectral characteristics of gamma-ray bursts observed by BATSE

Distributions of the continuum spectral characteristics of 260 bursts in the first Burst And Transient Source Experiement (BATSE) catalog are presented. The data are derived from flux calculated from BATSE Large Area Detector (LAD) four-channel discriminator data. The data are converted from counts to protons using a direct spectral inversion technique to remove the effects of atmospheric scattering and the energy dependence of the detector angular response. Although there are intriguing clusters of bursts in the spectral hardness ratio distributions, no evidence for the presence of distinct burst classes based in spectral hardness ratios alone is found. All subsets of bursts selected for their spectral characteristics in this analysis exhibit spatial distributions consistent with isotropy. The spectral diversity of the burst population appears to be caused largely by the highly variable nature of the burst production mechanisms themselves.

Pendleton, Geoffrey N.↗
DOE OSTI2026

Measurement of the p–$Σ^+$ correlation function in pp collisions at $\sqrt{s}$ = 13 TeV

In this letter, the first measurement of the femtoscopic correlation of protons and $Σ^+$ hyperons is presented and used to study the p–$Σ^+$ interaction. The measurement is performed with the ALICE detector in high-multiplicity triggered pp collisions at $\sqrt{s}$ = 13 TeV. The $Σ^+$ hyperons are reconstructed using a missing-mass approach in the decay channel to p + π 0 with π 0 → $γγ$, while both $Σ^+$ and protons are identified using a machine learning approach. These techniques result in a high reconstruction efficiency and purity, which allows the measurement of the p–$Σ^+$ correlation function for the first time. Thanks to the high significance achieved in the p–$Σ^+$ correlation signal, it is possible to discriminate between the predictions of different models of the N–$Σ$ interaction and to accomplish a first determination of the p–$Σ^+$ scattering parameters.

Femtoscopy↗
DOE OSTI2020

The crystal structures of a chloride-pumping microbial rhodopsin and its proton-pumping mutant illuminate proton transfer determinants

Microbial rhodopsins are versatile and ubiquitous retinal-binding proteins that function as light-driven ion pumps, light-gated ion channels, and photosensors, with potential utility as optogenetic tools for altering membrane potential in target cells. Insights from crystal structures have been central for understanding proton, sodium, and chloride transport mechanisms of microbial rhodopsins. Two of three known groups of anion pumps, the archaeal halorhodopsins (HRs) and bacterial chloride-pumping rhodopsins, have been structurally characterized. Here we report the structure of a representative of a recently discovered third group consisting of cyanobacterial chloride and sulfate ion-pumping rhodopsins, the Mastigocladopsis repens rhodopsin (MastR). Chloride-pumping MastR contains in its ion transport pathway a unique Thr-Ser-Asp (TSD) motif, which is involved in the binding of a chloride ion. The structure reveals that the chloride-binding mode is more similar to HRs than chloride-pumping rhodopsins, but the overall structure most closely resembles bacteriorhodopsin (BR), an archaeal proton pump. The MastR structure shows a trimer arrangement reminiscent of BR-like proton pumps and shows features at the extracellular side more similar to BR than the other chloride pumps. We further solved the structure of the MastR-T74D mutant, which contains a single amino acid replacement in the TSD motif. We provide insights into why this point mutation can convert the MastR chloride pump into a proton pump but cannot in HRs. Our study points at the importance of precise coordination and exact location of the water molecule in the active center of proton pumps, which serves as a bridge for the key proton transfer.

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

Measurement of cross sections for mesonless charged-current muon neutrino interactions on argon with and without protons at MicroBooNE

urrent and upcoming neutrino experiments at Fermilab will rely on liquid argon time projection chambers (LArTPCs) as the primary detector technology. To reach the ambitious precision required for their physics goals, a detailed understanding of neutrino-argon scattering must be achieved. For the present Short-Baseline Neutrino program, the dominant reaction channel is charged-current muon neutrino interactions leading to mesonless final states with and without protons. Using a large data set of neutrino interactions recorded by the MicroBooNE LArTPC detector at Fermilab, we report progress towards new measurements of differential cross sections in this channel. The analysis leverages multiple event reconstruction paradigms and observables specifically chosen to maximize sensitivity to nuclear effects of interest for improving neutrino scattering models. Related previous cross-section results from MicroBooNE and a preview of what to expect from the new analysis will both be featured in this presentation.

Liu, Liang [Fermilab]↗
DOE OSTI2023

Measurement of the total and differential Higgs boson production cross-sections at $ \sqrt{s} $ = 13 TeV with the ATLAS detector by combining the H → ZZ* → 4ℓ and H → γγ decay channels

The total and differential Higgs boson production cross-sections are measured through a combined statistical analysis of the H → ZZ* → 4ℓ and H → γγ decay channels. The results are based on a dataset of 139 fb –1 of proton–proton collisions at a centre-of-mass energy of 13 TeV, recorded by the ATLAS detector at the Large Hadron Collider. The measured total Higgs boson production cross-section is $55.5$$^{+4.0}_{–3.8}$ pb, consistent with the Standard Model prediction of 55.6 ± 2.5 pb. All results from the two decay channels are compatible with each other, and their combination agrees with the Standard Model predictions. A combined statistical interpretation of the measured fiducial cross-sections as a function of the Higgs boson transverse momentum is performed in order to probe the Yukawa couplings to the bottom and charm quarks. A similar interpretation is performed by including also the constraints from the measurements of Higgs boson production in association with a W or Z boson in the H → bb¯ and cc¯ decay channels.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1994

Proton and electron mean free paths: The Palmer consensus revisited

We present experimental and theoretical evidence suggesting that the mean free path of cosmic-ray electrons and protons may be fundamentally different at low to intermediate (less than 50 MV) rigidities. The experimental evidence is from Helios observations of solar energetic particles, which show that the mean free path of 1.4 MV electrons is often similar to that of 187 MV protons, even though proton mean free paths continue to decrease comparatively rapidly with decreasing rigidty down to the lowest channels (about 100 MV) observed. The theoretical evidence is from computations of particle scattering in dynamical magnetic turbulence, which predict that electrons will have a larger mean free path than protons of the same rigidity. In the light of these new results, 'consensus' ideas about cosmic-ray mean free paths may require drastic revision.

Bieber, John W.↗