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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Parallelized real-time physics codes for plasma control on DIII-D

A real-time safe multi-threading library was developed on the DIII-D plasma control system to optimize the real-time TORBEAM and real-time STRIDE physics codes. These physics codes are crucial for future fusion power plant operation as they provide information about electron cyclotron wave propagation and heating as well as inform about ideal plasma stability limits. The real-time TORBEAM code executed consistently in under 20 ms while the real-time STRIDE code computes in 100 ms. The multi-threading library developed in this work can be applied to other real-time physics-based codes that will be crucial for the next generation of fusion devices.

DIII-D↗
DOE OSTI2021

On the physics potential to study the gluon content of proton and deuteron at NICA SPD

The Spin Physics Detector (SPD) is a future multipurpose experiment foreseen to run at the NICA collider, which is currently under construction at the Joint Institute for Nuclear Research (JINR, Dubna, Russia). The physics program of the experiment is based on collisions of longitudinally and transversely polarized protons and deuterons at √s up to 27 GeV and luminosity up to 10 32 cm –2 s –1 . SPD will operate as a universal facility for the comprehensive study of the unpolarized and polarized gluon content of the nucleon, using complementary probes such as: charmonia, open-charm, and prompt-photon production processes. Furthermore, the aim of this work is to provide a thorough review of the physics objectives that can potentially be addressed at SPD, underlining related theoretical aspects and discussing relevant experimental results when available. Among different pertinent phenomena particular attention is drawn to the study of the gluon helicity, gluon Sivers and Boer-Mulders functions in the nucleon, as well as the gluon transversity distribution in the deuteron, via the measurement of single and double spin asymmetries.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Status and perspectives of neutrino physics

This review demonstrates the unique role of the neutrino by discussing in detail the physics of and with neutrinos. We deal with neutrino sources, neutrino oscillations, absolute masses, interactions, the possible existence of sterile neutrinos, and theoretical implications. In addition, synergies of neutrino physics with other research fields are found, and requirements to continue successful neutrino physics in the future, in terms of technological developments and adequate infrastructures, are stressed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Summary of ORSphere Critical and Reactor Physics Measurements

In the early 1970s Dr. John T. Mihalczo (team leader), J. J. Lynn, and J. R. Taylor performed experiments at the Oak Ridge Critical Experiments Facility (ORCEF) with highly enriched uranium (HEU) metal (called Oak Ridge Alloy or ORALLOY) to recreate GODIVA I results with greater accuracy than those performed at Los Alamos National Laboratory in the 1950s. The purpose of the Oak Ridge ORALLOY Sphere (ORSphere) experiments was to estimate the unreflected and unmoderated critical mass of an idealized sphere of uranium metal corrected to a density, purity, and enrichment such that it could be compared with the GODIVA I experiments. This critical configuration has been evaluated. Preliminary results were presented at ND2013. Since then, the evaluation was finalized and judged to be an acceptable benchmark experiment for the International Criticality Safety Benchmark Experiment Project (ICSBEP). Additionally, reactor physics measurements were performed to determine surface button worths, central void worth, delayed neutron fraction, prompt neutron decay constant, fission density and neutron importance. These measurements have been evaluated and found to be acceptable experiments and are discussed in full detail in the International Handbook of Evaluated Reactor Physics Benchmark Experiments. The purpose of this paper is summary summarize all the critical and reactor physics measurements evaluations and, when possible, to compare them to GODIVA experiment results.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Spin and diffractive physics with a fixed-target experiment at the LHC (AFTER-LHC)

We report on the spin and diffractive physics at a future multi-purpose f xed-target experiment with proton and lead LHC beams extracted by a bent crystal. The LHC multi-TeV beams allow for the most energetic f xed-target experiments ever performed, opening new domains of particle and nuclear physics and complementing that of collider physics, in particular that of RHIC and the EIC projects. The luminosity achievable with AFTER using typical targets would surpass that of RHIC by more than 3 orders of magnitude. The f xed-target mode has the advantage to allow for measurements of single-spin asymmetries with polarized target as well as of single-diffractive processes in the target region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Deep learning: A guide for practitioners in the physical sciences

Machine learning is finding increasingly broad applications in the physical sciences. This most often involves building a model relationship between a dependent, measurable output, and an associated set of controllable, but complicated, independent inputs. We present a tutorial on current techniques in machine learning—a jumping-off point for interested researchers to advance their work. We focus on deep neural networks with an emphasis on demystifying deep learning. We begin with background ideas in machine learning and some example applications from current research in plasma physics. We discuss supervised learning techniques for modeling complicated functions, beginning with familiar regression schemes, and then advancing to more sophisticated deep learning methods. We also address unsupervised learning and techniques for reducing the dimensionality of input spaces. Along the way, we describe methods for practitioners to help ensure that their models generalize from their training data to as-yet-unseen test data. We describe classes of tasks—predicting scalars, handling images, and fitting time-series—and prepare the reader to choose an appropriate technique. We finally point out some limitations to modern machine learning and speculate on some ways that practitioners from the physical sciences may be particularly suited to help.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Physics-guided dual implicit neural representations for source separation

Significant challenges exist in efficient data analysis of most advanced experimental and observational techniques because the collected signals often include unwanted contributions, such as background and signal distortions, that can obscure the physically relevant information of interest. To address this, we have developed a self-supervised machine-learning approach for source separation using a dual implicit neural representation framework that jointly trains two neural networks: one for approximating distortions of the physical signal of interest and the other for learning the effective background contribution. Our method learns directly from the raw data by minimizing a reconstruction-based loss function without requiring labeled data or pre-defined dictionaries. We demonstrate the effectiveness of our framework by considering a challenging case study involving large-scale simulated, as well as experimental, momentum-energy-dependent inelastic neutron scattering data in a four-dimensional parameter space, characterized by heterogeneous background contributions and unknown distortions to the target signal. The method is found to successfully separate physically meaningful signals from a complex or structured background even when the signal characteristics vary across all four dimensions of the parameter space. An analytical approach that informs the choice of the regularization parameter is presented. Our method offers a versatile framework for addressing source separation problems across diverse domains, ranging from superimposed signals in astronomical measurements to structural features in biomedical image reconstructions.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Short-range correlation physics at low renormalization group resolution

Recent experiments have succeeded in isolating processes for which short-range correlation (SRC) physics is dominant and well accounted for by SRC phenomenology. But an alternative and compelling picture emerges from renormalization group (RG) evolution to low RG resolution. At high RG resolution, SRCs are identified as components in the nuclear wave function with relative pair momenta greater than the Fermi momentum. Scale separation results in wave-function factorization that can be exploited with phenomenologies such as the generalized contact formalism or the low-order correlation operator approximation. Evolution to lower resolution shifts SRC physics from nuclear structure to the reaction operators without changing the measured observables. We show how the features of SRC phenomenology manifested at high RG resolution are cleanly identified at low RG resolution using simple two-body operators and local-density approximations with uncorrelated wave functions, all of which can be systematically generalized. We verify that the experimental consequences to date follow directly at low resolution from well-established properties of nucleon-nucleon interactions such as the tensor force. Thus the RG reconciles the contrasting pictures of the same experiment and shows how to get correct results using wave functions without SRC components. Finally, our demonstration has implications for the analysis of knockout reactions for which SRC physics is not cleanly isolated.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Accessing new physics with an undoped, cryogenic CsI CEvNS detector for COHERENT at the SNS

We consider the potential for a 10 kg undoped cryogenic CsI detector operating at the Spallation Neutron Source to measure coherent elastic neutrino-nucleus scattering and its sensitivity to discover new physics beyond the standard model (BSM). Through a combination of increased event rate, lower threshold, and good timing resolution, such a detector would significantly improve on past measurements. We considered tests of several BSM scenarios such as neutrino nonstandard interactions and accelerator-produced dark matter. This detector’s performance was also studied for relevant questions in nuclear physics and neutrino astronomy, namely the weak charge distribution of Cs and I nuclei and detection of neutrinos from a core-collapse supernova. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Revealing Fundamental Physics from the Daya Bay Neutrino Experiment Using Deep Neural Networks

Experiments in particle physics produce enormous quantities of data that must be analyzed and interpreted by teams of physicists. This analysis is often exploratory, where scientists are unable to enumerate the possible types of signal prior to performing the experiment. Thus, tools for summarizing, clustering, visualizing and classifying high-dimensional data are essential. Here in this work, we show that meaningful physical content can be revealed by transforming the raw data into a learned high-level representation using deep neural networks, with measurements taken at the Daya Bay Neutrino Experiment as a case study. We further show how convolutional deep neural networks can provide an effective classification filter with greater than 97% accuracy across different classes of physics events, significantly better than other machine learning approaches.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

A new approach to physics of nuclei

We employ the QCD sum rules method for description of nucleons in nuclear matter. We show that this approach provides a consistent formalism for solving various problems of nuclear physics. Such nucleon characteristics as the Dirac effective mass m* and the vector self-energy {Sigma}{sub V} are expressed in terms of the in-medium values of QCD condensates. The values of these parameters at saturation density and the dependence on the baryon density and on the neutron-to-proton density ratio is in agreement with the results, obtained by conventional nuclear physics methods. The contributions to m* and {Sigma}{sub V} are related to observables and do not require phenomenological parameters. The scalar interaction is shown to be determined by the pion-nucleon {sigma} term. The nonlinear behavior of the scalar condensate may appear to provide a possible mechanism of the saturation. The approach provided reasonable results for renormalization of the axial coupling constant, for the contribution of the strong interactions to the neutron-proton mass difference and for the behavior of the structure functions of the in-medium nucleon. The approach enables to solve the problems which are difficult or unaccessible for conventional nuclear physics methods. The method provides guidelines for building the nuclear forces. The three-body interactions emerge within the method in a natural way. Their rigorous calculation will be possible in the framework of self-consistent calculation in nuclear matter of the scalar condensate and of the nucleon effective mass m*.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Physics Flash December 2016

This is the December 2016 issue of Physics Flash, the newsletter of the Physics Division of Los Alamos National Laboratory (LANL). In this issue, the following topics are covered: Novel liquid helium technique to aid highly sensitive search for a neutron electrical dipole moment; Silverleaf: Prototype Red Sage experiments performed at Q-site; John L. Kline named 2016 APS Fellow; Physics students in the news; First Entropy Engine quantum random number generator hits the market; and celebrating service.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

High Energy Physics Research: Experimental & Theoretical (Final Report)

The research at the energy frontier was to explore high energy and luminosity collisions at the LHC using the ATLAS and CMS detectors to lead physics analyses in characterization of the Higgs Boson, to search for its potential partners, to lead searches for Dark Matter and to make extensive studies of Electroweak phenomena. The objectives are also to operate and upgrade the ATLAS and CMS detectors and their computing to optimize their physics performance in the present data taking and to enable the full exploitation of planned High Luminosity LHC. The research for the theory frontier was to analyze and interpret the new data from the experimental frontiers: energy, cosmic and intensity (Phenomenology), to investigate new theories of high energy physics extending the standard model by including gravity within consistent frameworks such as string theory, and examine their phenomenological and cosmological implications (String Theory and Theoretical Cosmology.)

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Constraining Physical Models at Gigabar Pressures

High-energy-density (HED) experiments in convergent geometry are able to test physical models at pressures beyond hundreds of millions of atmospheres. The measurements from these experiments are generally highly integrated and require unique analysis techniques to procure quantitative information. This work describes a methodology to constrain the physics in convergent HED experiments by adapting the methods common to many other fields of physics. As an example, a mechanical model of an imploding shell is constrained by data from a thin-shelled direct-drive exploding-pusher experiment on the OMEGA Laser System using Bayesian inference, resulting in the reconstruction of the shell dynamics and energy transfer during the implosion. The model is tested by analyzing synthetic data from a 1-D hydrodynamics code and is sampled using a Markov chain Monte Carlo to generate the posterior distributions of the model parameters. The goal of this work is to demonstrate a general methodology that can be used to draw conclusions from a wide variety of HED experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Applications of AdS/QCD and Light-Front Holography to Baryon Physics

The correspondence between theories in anti-de Sitter space and field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. These equations, for both mesons and baryons, give a very good representation of the observed hadronic spectrum, including a zero mass pion. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. The meson and baryon wavefunctions derived from light-front holography and AdS/QCD also have remarkable phenomenological features, including predictions for the electromagnetic form factors and decay constants. The approach can be systematically improved using light-front Hamiltonian methods. Some novel features of QCD for baryon physics are also discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Reco level Smin and subsystem Smin: improved global inclusive variables for measuring the new physics mass scale in MET events at hadron colliders

The variable {radical}s{sub min} was originally proposed in [1] as a model-independent, global and fully inclusive measure of the new physics mass scale in missing energy events at hadron colliders. In the original incarnation of {radical}s{sub min}, however, the connection to the new physics mass scale was blurred by the effects of the underlying event, most notably initial state radiation and multiple parton interactions. In this paper we advertize two improved variants of the {radical}s{sub min} variable, which overcome this problem. First we show that by evaluating the {radical}s{sub min} variable at the RECO level, in terms of the reconstructed objects in the event, the effects from the underlying event are significantly diminished and the nice correlation between the peak in the {radical}s{sub min}{sup (reco)} distribution and the new physics mass scale is restored. Secondly, the underlying event problem can be avoided altogether when the {radical}s{sub min} concept is applied to a subsystem of the event which does not involve any QCD jets. We supply an analytic formula for the resulting subsystem {radical}s{sub min}{sup (sub)} variable and show that its peak exhibits the usual correlation with the mass scale of the particles produced in the subsystem. Finally, we contrast {radical}s{sub min} to other popular inclusive variables such as H{sub T}, M{sub Tgen} and M{sub TTgen}. We illustrate our discussion with several examples from supersymmetry, and with dilepton events from top quark pair production.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Physics and Algorithm Enhancements for a Validated MCNP/X Monte Carlo Simulation Tool, Phase VII

Currently the US lacks an end-to-end (i.e., source-to-detector) radiation transport simulation code with predictive capability for the broad range of DHS nuclear material detection applications. For example, gaps in the physics, along with inadequate analysis algorithms, make it difficult for Monte Carlo simulations to provide a comprehensive evaluation, design, and optimization of proposed interrogation systems. With the development and implementation of several key physics and algorithm enhancements, along with needed improvements in evaluated data and benchmark measurements, the MCNP/X Monte Carlo codes will provide designers, operators, and systems analysts with a validated tool for developing state-of-the-art active and passive detection systems. This project is currently in its seventh year (Phase VII). This presentation will review thirty enhancements that have been implemented in MCNPX over the last 3 years and were included in the 2011 release of version 2.7.0. These improvements include 12 physics enhancements, 4 source enhancements, 8 tally enhancements, and 6 other enhancements. Examples and results will be provided for each of these features. The presentation will also discuss the eight enhancements that will be migrated into MCNP6 over the upcoming year.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Neutrino Cross Sections II: Neutrino Boogaloo. UF Task P3, Accelerator-Based Experimental Neutrino Physics. Final Report

We report on progress in a series of different directions within high energy physics research. 1. Neutrino research in hardware and software on the Minerva and MiniBooNE experiments 2. Experimental particle physics at the hadron colliders, with emphasis on research and development and data analysis on the CMS experiment operating at the CERN LHC. This includes research on the discovery and properties on the Higgs Boson. 3. Educational outreach through the Quarknet program, taking physics research into High School classrooms. 4. Theoretical and Phenomenological High Energy research, covering a broad range of activities ranging from fundamental theoretical issues to areas of immediate phenomenological importance. 5. Experiment searches for the Axion, as part of the ADMX experiment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗