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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Precise Measurement of the D s + Lifetime at Belle II

We measure the lifetime of the $D^+_s$ meson using a data sample of 207 fb -1 collected by the Belle II experiment running at the SuperKEKB asymmetric-energy e + e - collider. The lifetime is determined by fitting the decay-time distribution of a sample of 116 × 10 3 $D^+_s$ → φπ + decays. Our result is τ$D^+_s$ = (499.5 ± 1.7 ± 0.9) fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

High-Precision Spectroscopy of 20 O Benchmarking Ab Initio Calculations in Light Nuclei

The excited states of unstable 20 O were investigated via γ-ray spectroscopy following the 19 O(d, p) ⁢20 O reaction at 8 A⁢ MeV. By exploiting the Doppler shift attenuation method, the lifetimes of the $2^+_2$ and $3^+_1$ states were firmly established. From the γ-ray branching and E⁢2/M⁢1 mixing ratios for transitions deexciting the $2^+_2$ and $3^+_1$ states, the B⁡(E⁢2) and B⁡(M⁢1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. Finally, the reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the Ω c 0 Baryon

The first observation of the singly Cabibbo-suppressed Ω c 0 → Ω − K + and Ω c 0 → Ξ − π + decays is reported, using proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb − 1 , collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be B ( Ω c 0 → Ω − K + ) B ( Ω c 0 → Ω − π + ) = [ 6.08 ± 0.51 ( stat ) ± 0.40 ( syst ) ] % , B ( Ω c 0 → Ξ − π + ) B ( Ω c 0 → Ω − π + ) = [ 15.81 ± 0.87 ( stat ) ± 0.44 ( syst ) ± 0.16 ( ext ) ] % . In addition, using the Ω c 0 → Ω − π + decay channel, the Ω c 0 baryon mass is measured to be M ( Ω c 0 ) = 2695.28 ± 0.07 ( stat ) ± 0.27 ( syst ) ± 0.30 ( ext ) MeV , improving the precision of the previous world average by a factor of 4. © 2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2024

Observation of D s + → η ′ μ + ν μ , Precision Test of Lepton Flavor Universality with D s + → η ( ′ ) l + ν l , and First Measurements of D s + → η ( ′ ) μ + ν μ Decay Dynamics

By analyzing 7.33 fb − 1 of e + e − annihilation data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we report the observation of the semileptonic decay D s + → η ′ μ + ν μ , with a statistical significance larger than 10 σ , and the measurements of the D s + → η μ + ν μ and D s + → η ′ μ + ν μ decay dynamics for the first time. The branching fractions of D s + → η μ + ν μ and D s + → η ′ μ + ν μ are determined to be ( 2.235 ± 0.05 1 stat ± 0.05 2 syst ) % and ( 0.801 ± 0.05 5 stat ± 0.02 8 syst ) % , respectively, with precision improved by factors of 6.0 and 6.6 compared to the previous best measurements. Combined with the results for the decays D s + → η e + ν e and D s + → η ′ e + ν e , the ratios of the decay widths are examined both inclusively and in several ℓ + ν ℓ four-momentum transfer ranges. No evidence for lepton flavor universality violation is found within the current statistics. The products of the hadronic form factors f + , 0 η ( ′ ) ( 0 ) and the c → s Cabibbo-Kobayashi-Maskawa matrix element | V c s | are determined. The results based on the two-parameter series expansion are f + , 0 η ( 0 ) | V c s | = 0.452 ± 0.01 0 stat ± 0.00 7 syst and f + , 0 η ′ ( 0 ) | V c s | = 0.504 ± 0.03 7 stat ± 0.01 2 syst , which help to constrain present models on f + , 0 η ( ′ ) ( 0 ) . The forward-backward asymmetries are determined to be ⟨ A FB η ⟩ = − 0.059 ± 0.03 1 stat ± 0.00 5 syst and ⟨ A FB η ′ ⟩ = − 0.064 ± 0.07 9 stat ± 0.00 6 syst for the first time, which are consistent with the theoretical calculation. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Precise Measurement of Born Cross Sections for e + e − → D D ¯ at s = 3.80 − 4.95 GeV

Using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies ranging from 3.80 to 4.95 GeV, corresponding to an integrated luminosity of 20 fb − 1 , a measurement of Born cross sections for the e + e − → D 0 D ¯ 0 and D + D − processes is presented with unprecedented precision. Many clear peaks in the line shape of e + e − → D 0 D ¯ 0 and D + D − around the mass range of G ( 3900 ) , ψ ( 4040 ) , ψ ( 4160 ) , Y ( 4260 ) , and ψ ( 4415 ) , etc., are foreseen. These results offer crucial experimental insights into the nature of hadron production in the open-charm region. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Precise Measurement of the e + e − → D s + D s − Cross Section at Center-of-Mass Energies from Threshold to 4.95 GeV

Using the e + e − collision data collected with the BESIII detector operating at the BEPCII collider, at center-of-mass energies from the threshold to 4.95 GeV, we present precise measurements of the cross section for the process e + e − → D s + D s − using a single-tag method. The resulting cross section line shape exhibits several new structures, thereby offering an input for a future coupled-channel analysis and model tests, which are critical to understand vector charmonium-like states with masses between 4 and 5 GeV. Published by the American Physical Society 2024

Ablikim, M.↗
DOE OSTI2021

Effect of interfacial structures on phonon transport across atomically precise Si/Al heterojunctions

Phonons are important carriers of energy and information in many cryogenic devices used for quantum information science and in fundamental physics experiments such as dark matter detectors. In these systems phonon behavior can be dominated by interfaces, hence there is increasing demand for a more detailed understanding of interfacial phonon transport in relevant material systems. Previous studies have focused on understanding thermal transport over the entire phonon spectrum at and above room temperature. At ultra-low temperatures, however, knowledge is missing regarding athermal phonon behavior due to the challenge in modeling the extreme conditions in micro-scale, heterogeneous cryogenic systems, as well as extracting single-phonon information from a large ensemble. In this work, we delineate interfacial phonon transport using a combination of classical molecular dynamics (MD) and phonon wave packet simulations, to illustrate the consistency and differences between the ensemble- and single-phonon dynamics. We consider three single-crystal Si surface reconstructions --- (1×1), (v3×v3) and (7×7) --- and model both experimentally observed Si(1×1)/Al interfaces and hypothesized Si(v3×v3)/Al and Si(7×7)/Al interfaces. The overall interfacial thermal conductance calculated from non-equilibrium MD shows that for the Si(1×1)/Al system, the presence of Al twin grain boundaries can hinder phonon transport and reduce thermal conductance by 2--12% relative to single-crystal Al; whereas the Si (v3×v3) and (7×7) reconstructions can enhance it by 6--19%. Normal mode decomposition reveals that both the increase and decrease in conductance are related to inelastic phonon scattering. Single-phonon wave packet simulations show results consistent with NEMD, while further suggesting that phonon polarization conversion is significant even when elastic transmission dominates, and that the interfacial structures have anisotropic impacts on atomic vibrations along different lattice directions. Our findings suggest alternative perspectives in achieving selective phonon transport through controlling interfacial structures of materials with atomically-precise fabrication techniques, and that the phonon wave packet formalism is a potentially powerful method for developing a detailed understanding of non-equilibrium phenomena in the low-temperature limit.

Lu, Zexi↗
DOE OSTI2024

Precision spectroscopy of fast, hot, exotic isotopes using machine-learning-assisted event-by-event Doppler correction

We propose an experimental scheme for performing sensitive, high-precision laser spectroscopy studies on fast exotic isotopes. By inducing a stepwise resonant ionization of the atoms traveling inside an electric field and subsequently detecting the ion and the corresponding electron, time-, and position-sensitive measurements of the resulting particles can be performed. Using a mixture density network, we can leverage this information to predict the initial energy of individual atoms and thus apply a Doppler correction of the observed transition frequencies on an event-by-event basis. We conduct numerical simulations of the proposed experimental scheme and show that kHz-level uncertainties can be achieved for ion beams produced at extreme temperatures ( > 10 8 K), with energy spreads as large as 10 keV and nonuniform velocity distributions. The ability to perform in-flight spectroscopy, directly on highly energetic beams, offers unique opportunities to study short-lived isotopes with lifetimes in the millisecond range and below, produced in low quantities, in hot and highly contaminated environments, without the need for cooling techniques. Such species are of marked interest for nuclear structure, astrophysics, and new physics searches. Published by the American Physical Society 2024

Udrescu, S. M. (ORCID:000000021989576X)↗
DOE OSTI2024

Improved Precision Scaling for Simulating Coupled Quantum-Classical Dynamics

In this paper, we present a superpolynomial improvement in the precision scaling of quantum simulations for coupled quantum-classical systems. Such systems are found in, e.g., molecular-dynamics simulations within the Born-Oppenheimer approximation. By employing a framework based on the Koopman–von Neumann formulation of classical mechanics, we express the Liouville equation of motion as unitary dynamics and utilize phase kickback from a dynamical quantum simulation to calculate the quantum forces acting on classical particles. This approach allows us to simulate the dynamics of these classical particles without the overheads associated with measuring gradients and solving the equations of motion on a classical computer, resulting in a superpolynomial advantage at the price of increased space complexity. We demonstrate that these simulations can be performed in both microcanonical and canonical ensembles, enabling the estimation of thermodynamic properties from the prepared probability density. Published by the American Physical Society 2024

Simon, Sophia (ORCID:0000000332612338)↗
DOE OSTI2025

Precision beam diagnostics at the NuMI facility using muon monitor observations

The Neutrinos at the Main Injector (NuMI) facility at Fermilab delivers an intense neutrino beam for multiple experiments by producing pions that decay into neutrinos, muons, and other particles. Magnetic horns—the primary pion focusing elements in the NuMI beamline—exhibit predominantly linear optics, enabling a predictable relationship between the proton beam and the resulting pion and muon phase spaces. This study has two primary objectives: first, to evaluate and confirm the linearity of the horn focusing mechanism using analytical models and numerical simulations; and second, to demonstrate that key beam parameters—such as proton beam intensity, beam position on target, and horn current—can be extracted from muon monitor observations within this linear optics framework. Using a machine learning model trained on spill-by-spill muon monitor data, we infer the horn current with a precision of ±0.05%, the beam intensity with ±0.1%, and the beam position on target with ±0.018⁢ mm horizontally and ±0.013⁢ mm vertically. This approach provides a reliable cross-check of beam parameters, helping to reduce systematic uncertainties that are critical for future experiments such as the Deep Underground Neutrino Experiment, which will rely on the neutrino beam produced by the Long-Baseline Neutrino Facility.

Beam control↗
DOE OSTI2026

Precise 𝐾* ⁡(892) → 𝐾⁡𝜋 branching fractions

Although discovered more than sixty years ago, direct measurement of the 𝐾*⁡(892) → 𝐾⁡𝜋 branching fractions is a formidable challenge that has not been attempted. Typically they are assumed to obey the isospin limit in hundreds of particle data measurements. We show that an abundance of recent amplitude analyses and other data, however, enables recovery of the ratios ℬ⁡(𝐾 *+ → 𝐾 + ⁢𝜋 0 )/ℬ⁡(𝐾 *+ → 𝐾$^0_S$ ⁢𝜋 + ) and 4⁢ℬ⁡(𝐾 *0 → 𝐾$^0_S$ ⁢𝜋 0 )/ℬ⁡(𝐾 *0 → 𝐾 +⁢ 𝜋 − ) at ∼5% precision.

Gligorov, Vladimir V. [Sorbonne Université, Paris ↗
DOE OSTI2025

High-precision Penning trap mass measurements of neutron-rich chlorine isotopes at the 𝑁 = 28 shell closure

Although it is known that the N = 28 spherical shell closure erodes, the strength of the closure with decreasing proton number Z < 20 is an open question in nuclear structure. Here, in this region of interest, high-precision mass measurements of neutron-rich 43-45 Cl isotopes were performed at the Low Energy Beam and Ion Trap (LEBIT) when coupled to the National Superconducting Cyclotron Lab. The resulting mass excesses (MEs) are ME(⁴³Cl) = -24114.4(1.7) keV, ME(⁴⁴Cl) = -20450.8(10.6) keV, and ME(⁴⁵Cl) = -18240.1(3.7) keV, and improve the uncertainty of these masses by up to a factor of ∼40 compared to the previous values reported in the 2020 Atomic Mass Evaluation. Comparison to ab initio calculations using the Valence-Space In-Medium Similarity Renormalization Group (VS-IMSRG) shows good agreement up to and including the closure.

Erington, H. [Michigan State Univ., East Lansing, ↗
DOE OSTI2025

Precision measurement of the $Ξ^0_b$ baryon lifetime

A sample of 𝑝⁢𝑝 collision data, corresponding to an integrated luminosity of 5.4 fb −1 and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the $Ξ^0_b$ baryon to that of the $Λ^0_b$ baryon, 𝑟 𝜏 $≡$ $𝜏_{Ξ^0_b}$$/𝜏_{Λ^0_b}$. The value 𝑟$^{\textrm{Run 2}}_𝜏$ =1.004 ± 0.009 ± 0.006 is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain 𝑟 𝜏 =1.004 ± 0.008 ± 0.005. Multiplying by the known value of the $Λ^0_b$ lifetime yields $𝜏_{Ξ^0_b}$ = 1.475 ± 0.012 ± 0.008 ± 0.009 ps, where the last uncertainty is due to the limited knowledge of the $Λ^0_b$ lifetime. This measurement improves the precision of the current world average of the $Ξ^0_b$ lifetime by about a factor of two, and is in good agreement with the most recent theoretical predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Precision study of the massive Schwinger model near quantum criticality

We perform a numerical analysis of the massive Schwinger model in the presence of a background electric field. Using the Density Matrix Renormalization Group approach, we efficiently compute the spectrum of the Schwinger model on a staggered lattice with up to 3000 qubits. As a result, we achieve a precise computation of the critical mass of the massive Schwinger model to five digits using four different “criticality criteria,” observing perfect agreement among them Additionally, we discuss the effect of a four-fermion operator deformation of the Schwinger model and compute the critical mass for various values of the deformation parameter.

Critical phenomena↗
DOE OSTI2026

Precision Measurement of Neutrino Oscillation Parameters with 10 Years of Data from the NOvA Experiment

This Letter reports measurements of muon-neutrino disappearance and electron-neutrino appearance and the corresponding antineutrino processes between the two NOvA detectors in the NuMI neutrino beam. These measurements use a dataset with double the neutrino mode beam exposure that was previously analyzed, along with improved simulation and analysis techniques. A joint fit to these samples in the three-flavor paradigm results in the most precise single-experiment constraint on the atmospheric neutrino mass-splitting, $Δm^2_{32}= 2.431^{+0.036}_{-0.034} (-2.479^{+0.036}_{-0.036}) \times 10^{-3}$~eV$^2$ if the mass ordering is Normal (Inverted). In both orderings, a region close to maximal mixing with $\sin^2θ_{23}=0.55_{+0.06}^{-0.02}$ is preferred. The NOvA data show a mild preference for the Normal mass ordering with a Bayes factor of 2.4 (corresponding to 70% of the posterior probability), indicating that the Normal ordering is 2.4 times more probable than the Inverted ordering. When incorporating a 2D $Δm^2_{32}\textrm{--}\sin^2 2θ_{13}$ constraint based on Daya Bay data, this preference strengthens to a Bayes factor of 6.6 (87\%).

FOS: Physical sciences↗
DOE OSTI2025

Fabrication and characterization of a full-size ultra-precise lamellar grating for the Cosmic beamline at ALS-U

We have developed a new process for the production of ultra-precise variable line spacing (VLS) lamellar diffraction gratings through nanofabrication. The process enables the fabrication of full-size X-ray gratings with sub-nanometre accuracy in groove depth, an optimal land-to-groove ratio, and uniform groove depth across the entire grating area. We also established a method for evaluating VLS groove density variation using stitched Fizeau interferometry. The measurements confirmed the exceptionally high accuracy of the VLS groove density in the fabricated gratings, which is well within the specification tolerances while the residual groove density errors are vanishingly small. The gold-coated grating demonstrated near-theoretical diffraction efficiency across the energy range of 100–1200 eV.

36 MATERIALS SCIENCE↗
DOE OSTI2023

VecPAC: A Vectorizable and Precision-Aware CGRA

This paper proposes VecPAC -- a vectorizable and precision-aware coarse-grained reconfigurable array (CGRA) design. VecPAC integrates CGRA tiles with scalar functional units and specialized tiles with vector functional units that can trade off the number of vector lanes for the accuracy of the computation. We discuss the architecture design and present the related compilation framework. The experimental evaluation on a set of applications from three different domains (embedded, machine learning, and high-performance computing) shows that the hybrid design of VecPAC outperforms CGRAs with only scalar functional units by 1.48x, while providing higher scalability.

Tan, Cheng↗
DOE OSTI2025

Clarifying Terminology in Microbial Ecology: A Call for Precision in Scientific Communication

The rapid evolution of microbiology as a field of research has led to the introduction of new terminology and the adaptation of existing terms. However, inconsistencies in the use of these terms, including variations across different scientific disciplines, can lead to confusion and miscommunication within the scientific community. This article discusses the importance of precise terminology in microbiome research, highlighting examples where terms have been misused or redefined without clear justification. We also present a list of frequently used terms in microbial ecology along with their specific definitions. We argue that the misuse of terminology can hinder scientific progress by creating ambiguity and misunderstanding. To address this, we propose a set of guidelines for the consistent use of key terms and provide clear definitions for some of the most commonly misused or newly introduced terms in the field. The definitions provided herein will also function as a guide for young researchers new to the field of microbial ecology. Accurate and consistent use of terminology is crucial for effective communication and collaboration in microbiology research. By adhering to standardised definitions, researchers can ensure that their work is clearly communicated and contributes meaningfully to the progress of science.

definitions↗