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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Jefferson Lab Report

Jefferson Laboratory is finishing a major upgrade and has already started operations with the 12 GeV continuous electron beam. The main research direction is the study of the structure of hadrons, including a search for gluon excitations in the spectra of light mesons and baryons, and studies of multidimensional images of the nucleon. Studied of certain properties of atomic nuclei are also ongoing. Furthermore there is also an active program of searching for effects beyond the Standard Model in parity-violating electron scattering, as well as a search for new particles.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2011

The Jefferson Lab 12 GeV Upgrade

A major upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility is in progress. Construction began in 2008 and the project should be completed in 2015. The upgrade includes doubling the energy of the electron beam to 12 GeV, the addition of a new fourth experimental hall, and new experimental equipment in three of the experimental halls. A brief overview of this upgrade project is presented along with some highlights of the anticipated experimental program.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Configuration-space Faddeev calculation for proton-deuteron observables at energy E{sub lab} = 3 MeV

A new computational method for solving the nucleon-deuteron breakup scattering problem has been applied to study the elastic neutron- and proton-deuteron scattering on the basis of the configuration-space Faddeev-Noyes-Noble-Merkuriev equations. This method is based on the spline-decomposition in the angular variable and on a generalization of the Numerov method for the hyperradius. The Merkuriev-Gignoux-Laverne approach has been generalized for arbitrary nucleon-nucleon potentials and with an arbitrary number of partial waves taken into account. The nucleon-deuteron observables at the incident nucleon energy 3 MeV have been calculated using the charge-independent AV14 nucleon-nucleon potential including the Coulomb force for the proton-deuteron scattering. Results have been compared with those of other authors and with experimental proton-deuteron scattering data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Electroweak Physics at Jefferson Lab

The Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility provides CW electron beams with high intensity, remarkable stability, and a high degree of polarization. These capabilities offer new and unique opportunities to search for novel particles and forces that would require extension of the standard model. CEBAF is presently undergoing an upgrade that includes doubling the energy of the electron beam to 12 GeV and enhancements to the experimental equipment. This upgraded facility will provide increased capability to address new physics beyond the standard model.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Final results of the GEp(III) experiment at Jefferson Lab

The set of proton elastic form factor ratio data was extended to Q{sup 2} = 8.5 GeV{sup 2} with a recent experiment at JLab, GEp(III); the nucleon form factor data base is discussed and several conclusions presented. These data are the result of measurements of the polarization of the recoil proton; they have been known to differ significantly from Rosenbluth separation of cross section data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Baryon spectroscopy with CLAS at Jefferson Lab

A substantial part of the experimental efforts at the experimental Hall-B of Jefferson Laboratory is dedicated to this studies of light baryon spectroscopy. In this report a general overview of the experimental capabilities in the Experimental Hall-B will be presented together with preliminary results of recent double polarization measurements and finally overall status of the program.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

High-intensity positron microprobe at the Thomas Jefferson National Accelerator Facility

We present a conceptual design for a novel continuous wave electron-linac based high-intensity high-brightness slow-positron production source with a projected intensity on the order of 10{sup 10 }e{sup +}/s. Reaching this intensity in our design relies on the transport of positrons (T{sub +} below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. This design progressed through Monte Carlo optimizations of: electron/positron beam energies and converter target thickness, transport of the e{sup +} beam from the converter to the moderator, extraction of the e{sup +} beam from the magnetic channel, a synchronized raster system, and moderator efficiency calculations. For the extraction of e{sup +} from the magnetic channel, a magnetic field terminator plug prototype has been built and experimental results on the effectiveness of the prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Nb 3 Sn multicell cavity coating system at Jefferson Lab

Superconducting radio frequency niobium cavities are the building blocks of modern accelerators for scientific applications. Lower surface resistance, higher fields, and high operating temperatures advance the reach of the future accelerators for scientific discovery as well as potentially enabling cost-effective industrial solutions. We describe the design and performance of an Nb 3 Sn coating system that converts the inner surface of niobium cavities to an Nb 3 Sn film. The niobium surface, heated by radiation from the niobium retort, is exposed to Sn and SnCl 2 vapor during the heat cycle, which results in about 2 μm Nb 3 Sn film on the niobium surface. Film composition and structure as well as radio frequency properties with 1-cell R&D cavities and 5-cell practical accelerator cavities are presented.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

From lab to lamp: Understanding downconverter degradation in LED packages

Downconverters, primarily inorganic phosphors, are critical components in white solid-state LED-based lighting and liquid crystal display backlights. Research efforts have led to a fundamental understanding of a downconverter's absorption, photoluminescence, and efficiency as a function of composition, structure, and processing conditions. However, considerably less work has focused on the reliability of phosphors once they are incorporated into LED packages. Solving these issues is often the final step before the commercialization of new materials, but the significant resources and time required to evaluate and mitigate materials failure are rarely discussed in the literature. In this Perspective, we discuss the need for conducting downconverter reliability testing and the potential of accelerating, screening, and understanding downconverter failure modes. Our focus highlights the mechanisms of failure and discusses how this influences materials selection and the design of different LED packages. We also stress the potential for accelerated reliability testing protocols and note the potential role first-principles calculations and data-driven models could play in establishing the compositional-processing trends for different aspects of downconverter reliability. In conclusion, we close with possible research directions that could improve downconverter reliability and emphasize the importance of assessing a material's (chemical) stability where multiple manufacturing and processing steps can dictate system performance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Cloud microphysical response to entrainment and mixing is locally inhomogeneous and globally homogeneous: Evidence from the lab

Entrainment of dry air into clouds strongly influences cloud optical and precipitation properties and the response of clouds to aerosol perturbations. The response of cloud droplet size distributions to entrainment–mixing is examined in the Pi convection-cloud chamber that creates a turbulent, steady-state cloud. The experiments are conducted by injecting dry air with temperature (T e ) and flow rate (Q e ) through a flange in the top boundary, into the otherwise well-mixed cloud, to mimic the entrainment–mixing process. Due to the large-scale circulation, the downwind region is directly affected by entrained dry air, whereas the upwind region is representative of the background conditions. Droplet concentration (Cn) and liquid water content (L) decrease in the downwind region, but the difference in the mean diameter of droplets (D m ) is small. The shape of cloud droplet size distributions relative to the injection point is unchanged, to within statistical uncertainty, resulting in a signature of inhomogeneous mixing, as expected for droplet evaporation times small compared to mixing time scales. As T e and Q e of entrained air increase, however, Cn, L, and D m of the whole cloud system decrease, resulting in a signature of homogeneous mixing. The apparent contradiction is understood as the cloud microphysical responses to entrainment and mixing differing on local and global scales: locally inhomogeneous and globally homogeneous. This implies that global versus local sampling of clouds can lead to seemingly contradictory results for mixing, which informs the long-standing debate about the microphysical response to entrainment and the parameterization of this process for coarse-resolution models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

A New Light for Berkeley Lab—the Advanced Light Source Upgrade

The Advanced Light Source Upgrade Project (ALS-U) will leverage multibend achromat technology to endow the ALS with revolutionary soft X-ray capabilities, and has recently received formal approval to proceed to the preliminary design phase. Soft X-rays are a critical diagnostic tool for enabling the understanding and control of heterogeneous, hierarchical functional materials and chemical synthesis platforms since they can reveal chemical, electronic, and magnetic properties with very high sensitivity. Although the ALS has a strong track record in soft X-ray science over the last 25 years, it, like most other existing storage-ring-based X-ray light sources, lacks the simultaneous combination of nanometer spatial resolution, diverse spectroscopic contrast, and broad temporal sensitivity required to image the location of molecules, ions, and electrons, and to measure how their components migrate and interact to support efficient function. The high coherent flux of the upgraded ALS willenable a suite of tools that encompass 3D nanoscale imaging with high spectral sensitivity over broad space and time scales, dramatically amplifying the already high impact of ALS soft X-ray spectroscopies. Relative to many other synchrotron light source upgrade projects or new facilities being built today, the upgraded ALS will operate at a low electron-beam energy of 2 GeV and a high current of 500 mA, and is optimized for soft X-rays. Its soft X-ray coherent flux will be orders of magnitude higher than that of the existing ALS and beyond the coherent flux of any storage-ring-based light source operating, under construction, or currently planned. In total, the upgraded facility will provide an unprecedented combination of high stability, quasi-continuous radiation, and the highest possible coherent soft X-ray flux.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

A New Era for Jefferson Lab

On a cool Saturday morning in late April a seemingly endless stream of cars turned off Jefferson Avenue in Newport News, Virginia, bringing 12,000 people ages 1 to 91 to the Open House to learn more about “the new era in science” at the Thomas Jefferson National Accelerator Facility. Here, the visitors were dazzled by the complex equipment, the enthusiastic staff, and the advanced technology at the Laboratory.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Does the stellar distribution flare? A comparison of stellar scale heights with LAB H I data

The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

AI-supported mini-labs: combining smartphone-based experiments and multimodal AI

Multimedia learning has always been a topic in physics education—whether through specialized digital data acquisition systems, simulations, or animations. Due to increasing digitalization, more and more media from our everyday lives have also found their way into education in recent decades. This contribution introduces a conceptual framework and illustrative examples for AI-supported experimentation in physics education. It does not yet present empirical data but outlines directions for forthcoming classroom studies evaluating learning outcomes and engagement.

generative AI↗
DOE OSTI2018

Search for creation of electrons in lab

Here, we examine the physics motivations to search for lepton number violations in the laboratory, in particular by studying the important nuclear transition called neutrinoless double beta decay, which consists in the creation of a pair of electrons. We address some major shortcomings of the Standard Model of electroweak interactions, arguing that most of them can be solved simply within extended models with Majorana neutrinos. At the same time, we discuss the difficulties of obtaining precise predictions for the neutrinoless double beta decay rate and strengthen the case of probing Majorana neutrino masses of about 10 meV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Quasi elastic cross sections for the Bi-209(e, e-prime p) Pb-208 reaction: Jefferson Lab experiment E06007

Quasi elastic cross sections were measured for the first time for both negative and positive missing momenta for the {sup 209}Bi(e,e'p){sup 208}Pb reaction leading to the ground state and hole states of (208)Pb. Experimental cross sections obtained between -0.3 GeV/c to 0.3 GeV/c agree with theoretical calculations using RDWIA techniques both in shape and magnitude for the ground state. The data for the ground state production of {sup 208}Pb are consistent with a theoretical model assuming a single proton(1.06 +- 0.10) in the 1h9/2 orbit in {sup 209}Bi.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Studies of GPDs at Jefferson Lab: results and future experiments

Here, the Generalized Parton Distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply Virtual Compton Scattering (DVCS) on a proton or neutron (N), eN → e'N'γ, is one of the simplest processes that can be described in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, process where a photon is emitted by the incident or scattered electron, can be accessed via cross section measurements or exploiting their interference which give rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading order GPDs (H, E, $\tilde{H} $, $\tilde{E} $) for the two quark flavors depending on the observable and the type of target.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗