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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Direct Comparison of M\o ller and Compton Polarimeters in Hall C at Jefferson Lab

Knowledge of the electron beam polarization is one of the most important systematic uncertainties in precision, parity-violating electron scattering experiments with next generation experiments aiming to measure the electron beam polarization to better than 0.5\%. At high energies, the most typical polarimetry techniques are M\o ller (polarized electron-electron) and Compton (polarized electron-photon) scattering. The use of two techniques with different systematic uncertainties provides confidence in the extracted beam polarization. Direct comparisons of the two polarimetry techniques are challenging in that Compton polarimeters typically desire maximum beam flux (high beam currents) while M\o ller polarimeters need to limit the beam current to avoid depolarization effects in the target. We have performed a direct comparison of the M\o ller and Compton polarimeters in experimental Hall C at Jefferson Lab. This test is unique in that the data were taken sequentially under identical beam conditions at ?4.5~?A. We found excellent agreement between the Hall C M\o ller and Compton polarimeters. Combined with high-current Compton data, we were also able to limit the beam current dependence of the beam polarization to 1\% or less up to a beam current of 180~?A.

Gaskell, David↗
DOE OSTI2017

Impact of Jefferson Lab Data on Global PDF Analysis

This talk will review new insights into the quark structure of the nucleon that have been made with recent global QCD analysis of parton distributions, using new analysis techniques to take into account the latest high-precision data from Jefferson Lab.

Melnitchouk, Wolodymyr↗
DOE OSTI2017

Overview of the SIDIS/TMD program at Jefferson Lab

The study of the single-hadron semi-inclusive deep inelastic scattering process (SIDIS) is a rapidly developing and expanding area of inquiry in hadronic physics, owing to the prospect of realizing a precision three-dimensional imaging of the quark structure of the nucleon in momentum space. Measurements of the azimuthal angular distributions of hadrons produced at large values of z = Eh=? and "small" transverse momentum pT ~ \Lambda_?QCD in deep inelastic lepton-nucleon scattering provides access to novel features of nucleon structure that are inaccessible in traditional inclusive DIS, including the e?ects of initial-state quark transverse momentum, transverse polarization of the parent nucleon and the struck quark, and "flavor tagging" due to the varying sensitivity of di?erent hadron species to di?fferent quark flavors. The Continuous Electron Beam Accelerator Facility (CEBAF) at Je?erson Lab has recently completed an upgrade to a maximum beam energy of 11 GeV at ?ve passes for electron scattering experiments. The energy upgrade of CEBAF, combined with its already unrivaled intensity, duty cycle and polarization, facilitates a three-dimensional nucleon imaging program of unprecedented precision in the valence region. In this talk,I will present a brief overview of the planned CEBAF SIDIS program in experimental Halls A, B and C.

Puckett, Andrew↗
DOE OSTI2017

New Deeply Virtual Compton Scattering results from Jefferson Lab

Deeply Virtual Compton Scattering (DVCS) is the easiest reaction that accesses the Generalized Parton Distributions (GPDs) of the nucleon. GPDs offer the exciting possibility of mapping the 3-D internal structure of protons and neutrons by providing a transverse image of the constituents as a function of their longitudinal momentum. A vigorous experimental program is currently pursued at Jefferson Lab (JLab) to study GPDs through DVCS. New results from Hall A will be shown and discussed. Special attention will be devoted to the applicability of the GPD formalism at the moderate values of momentum transfer (Q2) available at JLab. We will conclude with a brief overview of additional DVCS experiments under analysis and planned with the future Upgrade of JLab to 12 GeV.

Camacho, Carlos Munoz↗
DOE OSTI2017

Separated pi0 electroproduction cross sections off the nucleon at Jefferson Lab Hall A

We report final results for L/T separated pi0 electroproduction cross sections off the proton, the neutron and the deuteron, measured in Hall A of Jefferson Lab. We found a large transverse response for both the proton and neutron cases, pointing to a possible dominance of higher-twist transversity GPD contributions. For the first time, a flavor decomposition of the u and d quark contributions to the cross section will be shown.

Sabatie, Franck↗
DOE OSTI2017

Field Mapper for Superconducting Torus Magnet for the Jefferson Lab 12GeV Upgrade

As part of the Jefferson Lab 12 GeV upgrade, the Hall B magnet system requires two conduction cooled superconducting magnets ? a Torus and a Solenoid. The Torus consists of 6 trapezoidal coils connected in series with an operating current of 3770 A. During commissioning of the torus magnet, field mapping was carried out at different levels of operating current in order to determine the field profile and field error table. In order to meet the physics requirement of the field accuracy we need magnetic field strength measurements which are accurate at the 0.1% level, and we need to know radius and azimuth to 0.1 mm and z to 0.5 mm. The center line of the torus magnet is approximately 6 m from ground level and the overall height of the torus magnet is approximately 8.5 m. There is also limited space around the magnet and in between the coils. Field mapping had to be carried out along the Z axis (i.e. along the bore) and at 4 radial locations between each coil. These restrictions provided certain challenges for the magnetic field mapping task. The mapper prototype was built and tested prior to use on the Torus itself. In this presentation the field mapper design, prototyping and actual data collection procedure will be presented.

Rajput-Ghoshal, Renuka↗
DOE OSTI2016

Overview of SIDIS results from Hall B at Jefferson Lab

We present studies of spin and azimuthal asymmetries in pion production in semi-inclusive deep inelastic scattering (SIDIS), using the data sets from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab with polarized $NH_3$ and unpolarized hydrogen targets. Three run periods, e1-6, e1-f and eg1-dvcs used respectively 5.7, 5.5 and 5.8 GeV longitudinally polarized electron beam and unpolarized liquid hydrogen (e1-6, e1-f) and polarized $NH_3$ (eg1-dvcs) targets. Pion channels ($\pi^+$, $\pi^-$, $\pi^0$) were studied over a broad kinematical range ($x = 0.1 - 0.6$, $Q^2 = 1.0 - 4.5 $ GeV$^2$, $z = 0.0 - 1.0$, $\Phperp^2 = 0.0 - 1.0$ GeV$^2$, and $-180^\circ < \phi < 180^\circ$). These measurements give insights into the transverse momentum dependence of parton distribution functions (PDFs) for different polarization states, describing the dynamics of quarks and gluons inside of the proton.

Avakian, Harut↗
DOE OSTI2023

Watch it again-or for the first time: Panel discussion and Q&A on First Lab Director J. Robert Oppenheimer

On June 19, 2023, at the National Security Sciences Building (NSSB) auditorium, LANL Director Thom Mason, LANL physicist Anna Llobet, American Prometheus author Kai Bird, and retired Senate staff member Tim Rieser discussed the life, work and legacy of first Lab Director J. Robert Oppenheimer. The panel event was moderated by LANL senior historian Alan Carr.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2023

Backup Power Performance of Solar-plus-Storage Systems during Routine Power Interruptions: A Case Study Application of Berkeley Lab’s PRESTO Model

This technical brief estimates the expected performance of a solar photovoltaic and energy storage system (PVESS) for providing backup power during short-duration power interruption events, accounting for the unpredictable nature of those events. The analysis relies on the Power Reliability Event Simulation TOol (PRESTO), a publicly available model developed by Berkeley Lab to simulate the occurrence of short-duration power interruption events at the county-level. A separate storage dispatch model is then used to simulate PVESS operation and backup performance for each of the large number of interruption events produced by PRESTO. In performing this simulation, the analysis accounts for how the customer operates its battery on a day-to-day basis—in this case, we assume the battery is cycled each day in response to time-of-use rates—and how that, in turn, impacts the battery’s state of charge at the beginning of each interruption event. The analysis presented here is intended to demonstrate an application of the PRESTO model as well as to illustrate some of the key determinants of PVESS backup power performance during short-duration power interruption events. The analysis focuses initially on a typical single-family home in Maricopa County, Arizona, and includes a limited set of scenarios related to system sizing, backup power configuration, and whether the customer charges its battery storage system from the grid during normal operating conditions. The analysis also presents comparative results for two other counties, in Massachusetts (Middlesex) and California (Los Angeles), illustrating how regional differences in climate, interruption patterns, and retail rate structures can affect PVESS performance as a backup power source. In the conclusions, we highlight a number of other important considerations for evaluating PVESS backup power capabilities.

14 SOLAR ENERGY↗
DOE OSTI2023

Transversely Polarized Solid Target for Hall B at Jefferson Lab

The physics program for Hall B at Jefferson Lab includes multiple, high-impact experiments scattering electrons from transversely polarized protons. These experiments will measure, for example, the Transverse Momentum Distributions and the Generalized Parton Distribution for protons, using, respectively, semi-inclusive deep inelastic scattering and deeply virtual Compton scattering. In this talk I will discuss the technical challenges to implementing a polarized solid-state target in the Hall B experimental environment, examine potential solutions, and describe the current status of the target design.

Keith, Christopher↗
DOE OSTI2023

The beam test of the lead tungstate calorimeter prototype with SiPM readout at Jefferson Lab

The lead tungstate crystals (PWO4) are a well-known radiator material for precise homogeneous electromagnetic calorimetry. In nuclear physics experiments, the typical way to read out the crystals is using conventional photomultiplier tubes (PMTs). In the case of the presence of a magnetic field, such a method has some complications and requires a passive PMT shielding design. The recent development of Silicon Photomultipliers (SiPMs) with small pixel pitch sizes and relatively small noise levels opens an opportunity avenue to use such a device as an alternative to conventional PMTs. The SiPM readout method may be beneficial for future nuclear physics and collider experiments. We are presenting the beam test results of the calorimeter prototype instrumented with SiPM readout performed at Jefferson Lab. The SiPM readout performance was compared with PMT readout measured at the same experimental conditions. The prototype was successfully tested using beam of photons in the energy range between 3 GeV and 11 GeV in experimental Hall D. The detector performance was also studied using a secondary beam of positrons provided by Hall D pair spectrometer.

Berdnikov, Vladimir↗
DOE OSTI2024

First-generation college student forges ahead, now key to Lab's mission

Fatima Woody was just 17 and a student at Pojoaque Valley High School when she first started her career as a Los Alamos Neutron Science Center receptionist. Now she's in a crucial role that keeps plutonium pit production and other mission processes operating with as little interruption as possible. Over nearly four decades, Fatima has gradually advanced from her initial positions as a receptionist and administrative secretary to become a computer technician, then a computer system professional who specializes in project management. Today, she coordinates the workflow for nearly two dozen deployed information technology technicians who keep the computer systems and networks operating at the high-tech complex that houses the Lab's Plutonium Facility.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2023

Testing of Microchannels and Lab-Grown Stress Corrosion Cracks for Quantification of Aerosol Transmission

The formation of a stress corrosion crack (SCC) in the canister wall of a dry cask storage system (DCSS) has been identified as a potential issue for the long-term storage of spent nuclear fuel. The presence of an SCC in a storage system could represent a through-wall flow path from the canister interior to the environment. Modern, vertical DCSSs are of particular interest due to the commercial practice of using higher backfill pressures in the canister, up to approximately 800 kPa, compared to their horizontal counterparts. This pressure differential offers a relatively high driving potential for blowdown of any particulates that might be present in the canister. In this study, the rates of gas flow and aerosol transmission of a spent fuel surrogate through an engineered microchannel with dimensions representative of an SCC were evaluated experimentally using coupled mass flow and aerosol analyzers. The microchannel was formed by mating two gage blocks with a linearly tapering slot orifice nominally 13 μm (0.005 in.) tall on the upstream side and 25 μm (0.0010 in.) tall on the downstream side. The orifice is 12.7 mm (0.500 in.) wide by 8.86 mm (0.349 in.) long (flow length). Surrogate aerosols of cerium oxide, CeO 2 , were seeded and mixed with either helium or air inside a pressurized tank. The aerosol characteristics were measured immediately upstream and downstream of the simulated SCC at elevated and ambient pressures, respectively. These data sets are intended to add to previous testing that characterized SCCs under well-controlled boundary conditions through the inclusion of testing improvements that establish initial conditions in a more consistent way. While the engineered microchannel has dimensions similar to actual SCCs, it does not reproduce the tortuous path the aerosol laden flow would have to traverse for eventual transmission. SCCs can be rapidly grown in a laboratory setting given the right conditions, and initial characterization and clean-flow testing has begun on lab grown crack samples provided to Sandia National Laboratories (SNL). Many such samples are required to produce statistically relevant transmission results, and SNL is developing a procedure to produce samples in welded steel plates. These ongoing testing efforts are focused on understanding the evolution in both size and quantity of a hypothetical release of aerosolized spent fuel particles from failed fuel to the canister interior and ultimately through an SCC.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Jefferson Lab Injector Beamline Upgrade

The Jefferson Lab injector beamline upgrade was completed in 2023, with vacuum improvements throughout the region. I will discuss the effects of the vacuum improvement on photocathode lifetime, the particulate control measures instituted to protect SRF accelerating cavities, and the latest JLab extreme high vacuum gun installation.

Stutzman, Marcy↗
DOE OSTI2023

Characterization of Lab-Grown Cracks for Aerosol Transmission Testing

Motivation: Determine the length and opening of two lab-grown cracks, designated as LT-14 and LT-28, representative of stress corrosion cracks in spent nuclear fuel dry storage casks to supplement future testing of gas and aerosol transport. Problem: The extreme aspect ratio of the crack length to opening requires that imaging occurs in stages with the results merged before final analysis. Method: High magnification (1500x) optical images of both sides of the two plates were acquired. 20x stitched images with LSCM were acquired, fully stitched along the length, and leveled with newly developed PLATES Method in MATLAB®. Conclusion for LT-14: Side 1 is 47.25 mm long and has 366 separate crack features with an average length of 23.50 µm and an average opening of 8.27 µm. Side 2 is 69.44 mm long and has 550 separate crack features with an average length of 81.63 µm and an average opening of 67.70 µm. Conclusion for LT-28: Side 1 is 71.95 mm long and has 1,127 separate crack features with an average length of 42.27 µm and an average opening of 10.31 µm. Side 2 is 74.88 mm long and has 520 separate crack features with an average length of 98.13 µm and an average opening of 14.99 µm. The adjacent crack on side 1 is 18.95 mm long and has 37 separate crack features with an average length of 17.46 µm and an average opening of 10.42 µm. The adjacent crack on side 2 is 26.40 mm long and has 55 separate crack features with an average length of 87.26 µm and an average opening of 48.29 µm. Each adjacent crack is approximately 26 mm from the main crack.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Large-x partons from Jefferson Lab to the LHC

This project addressed the longitudinal quark and gluon structure of hadrons, a key topic in the 2015 and 2023 NSAC long range plans for nuclear science. The research encompassed and combined theoretical studies with advanced Quantum Chromo Dynamics (QCD) analysis of experimental data, from Jefferson Lab to the Large Hadron Collider. The results have pushed the boundaries in both aspects, and capitalized on the results and methods developed in previous grant renewals.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗