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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Magnetic Measurements and Alignment Results of LQXFA/B Cold Mass Assemblies at Fermilab

MQXFA production series quadrupole magnets are being built for the Hi-Lumi (HL) LHC upgrade by the U.S. Accelerator Upgrade Project (US-HL-LHC AUP). These magnets are being placed in pairs, as a cold mass, within cryostats at Fermilab, and are being tested to assess alignment and magnetic performance at Fermilab's horizontal test stand facility. The ~10 m - long assembly must meet stringent specifications for quadrupole strength and harmonic field integrals determination, magnetic axis position, and for magnet variations in positioning and local field profile. Here this paper describes the results of the magnetic and alignment measurements which characterize the first LQXFA/B assembly.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Measurement of the phase between strong and electromagnetic amplitudes in the decay J/ψ → ϕη

The first direct measurement of the relative phase between the strong and electromagnetic amplitudes for a J/ψ decaying into a vector-pseudoscalar final state is performed using 26 energy points of e + e − annihilation data between 3.00 GeV and 3.12 GeV. The data sets were collected by the BESIII detector with a total integrated luminosity of 452 pb −1 . By investigating the interference pattern in the cross section lineshape of e + e − → ϕη, the relative phase between the strong and electromagnetic amplitudes of J/ψ decay is determined to be within [133°, 228°] at 68% confidence level.

QCD↗
DOE OSTI2020

First Field Measurements of the 15 T Nb 3 Sn Dipole Demonstrator MDPCT1

Within the US Magnet Development Program (MDP) a 15 T Nb 3 Sn dipole was developed, to demonstrate a magnet design for a post-LHC pp Collider. Specifically, the magnet design is based on 60 mm aperture 4-layer shell-type coils, graded between the inner and outer layers to maximize the magnet performance. The cable in the two innermost layers has 28 strands 1.0 mm in diameter and the cable in the two outermost layers has 40 strands 0.7 mm in diameter. Both cables use RRP Nb3Sn wires produced by Bruker-OST. Magnet coils are surrounded by vertically-split thick iron laminations, con-nected by aluminum I-clamps, and a thick stainless-steel skin. The magnet was tested at the Vertical Magnet Test Facility (VMTF) at Fermilab. This paper reports the first results of magnetic measure-ments of the 15 T Nb 3 Sn dipole demonstrator including geometrical harmonics, coil magnetization and iron saturation effects. The ex-perimental data are compared with the magnetic calculations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Constraining nuclear matter parameters with GW170817

The tidal measurement of gravitational waves from the binary neutron star merger event GW170817 allows us to probe nuclear physics that suffers less from astrophysical systematics compared to neutron star radius measurements with electromagnetic wave observations. Recent research found strong correlation among neutron-star tidal deformabilities and certain combinations of nuclear parameters associated with the equation of state. These relations were then used to derive bounds on such parameters from GW170817 assuming that the relations and neutron star masses are known exactly. In this work, we expand on this important work by taking into account a few new considerations: (1) a broader class of equations of state; (2) correlations with the mass-weighted tidal deformability that was directly measured with GW170817; (3) how the relations depend on the binary mass ratio; (4) the uncertainty from equation of state variation in the correlation relations; (5) adopting the updated posterior distribution of the tidal deformability measurement from GW170817. Upon these new considerations, we find GW170817 90% confidence intervals on nuclear parameters (the incompressibility K 0 , its slope M 0 , and the curvature of symmetry energy K sym,0 at nuclear saturation density) to be 81 MeV ≤K 0 ≤362 MeV, 1556 MeV ≤M 0 ≤ 4971 MeV, and -259 MeV ≤Ksym, 0 ≤32 MeV, which are more conservative than previously found with systematic errors more properly taken into account.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

The Effects of the Local Environment on a Compact Radio Interferometer I: Cross-Coupling in the Tianlai Dish Pathfinder Array

The visibilities measured by radio astronomical interferometers include non-astronomical correlated signals that arise from the local environment of the array. These correlated signals are especially important in compact arrays such as those under development for 21cm intensity mapping. The amplitudes of the contaminated visibilities can exceed the expected 21cm signal and represent a significant systematic effect. We study the receiver noise radiated by antennas in compact arrays and develop a model for how it couples to other antennas. We apply the model to the Tianlai Dish Pathfinder Array (TDPA), a compact array of 16, 6-m dish antennas. The coupling model includes electromagnetic simulations, measurements with a network analyzer, and measurements of the noise of the receivers. We compare the model to drift-scan observations with the array and set requirements on the level of antenna cross-coupling for 21cm intensity mapping instruments. Here, we find that for the TDPA, cross-coupling would have to be reduced by three orders of magnitude in order to contribute negligibly to the visibilities.

21cm intensity mapping↗
DOE OSTI2023

Performance and Commissioning of the BigBite Timing Hodoscope for Nucleon Form Factor Measurements at Jefferson Lab

The BigBite Timing Hodoscope detector is the primary subject of this thesis. The Super BigBite Spectrometer is a Jefferson Lab Hall A Collaboration project that has and will continue to measure nucleon electromagnetic form factors. This spectrometer includes the Timing Hodoscope which provides high resolution particle timing data for scattered electrons in the electron arm of BigBite. The Timing Hodoscope utilizes 90, 25 × 25 × 600 mm3 scintillator bars stacked on top of each other to form a single detector plane, and these bars are connected to 180 photo-multiplier tubes via light guides. Particles collide with the scintillating material creating a shower of optical photons and these particle events in the bars are collected to generate signals that are readout by the data acquisition (DAQ) electronics. NINO ASIC amplifier-discriminator cards output signals from the photo-multiplier tubes into analogue and logic signals, which are sent to analogue-to-digital (ADC) and time-to-digital (TDC) converter data acquisition readout modules. This data is then used for analysis of the detector. The focus of this thesis is the construction, commissioning, calibration, and performance of the BigBite Timing Hodoscope before and during the first of five nucleon electromagnetic form factor experiments at Jefferson Lab Hall A. Before the neutron magnetic form factor, G n M, experiment, cosmic ray data was collected during commissioning to confirm proper operation of the Timing Hodoscope electronics by observing the ADC and TDC data. Commissioning studies for charge normalization, gain matching, and other ADC and TDC detector data variables were performed before moving the detector into Hall A. Following installation in Hall A, several calibration studies were implemented to fine-tune the detector in preparation for use in the experiment. The calibration studies included analysis of timing cuts, TDC alignment, the time-walk effect, time difference offsets, and scintillator velocity corrections. Once the Timing Hodoscope was well-calibrated, data-taking during the experiment commenced and the beam-on-target data was used to characterize the Timing Hodoscope performance during the G n M experiment run-time. The performance analysis included studies observing energy deposit, cluster size, rates, accidentals, pile-up, tracking efficiency, position resolution, and time resolution. After application of physics cuts to ensure a data set comprised of particle tracks corresponding to elastic electrons, which is the main data of interest for measurement of G n M, the Timing Hodoscope is shown on average across all kinematic settings to have a >98% tracking efficiency, a position resolution of 4-6 cm in the non-dispersive plane and 1.5-2 cm in the dispersive plane, and a time resolution of 500-750 ps. These performance results are compared to a GEANT4 based performance simulation of the BigBite Timing Hodoscope for reference, showing to what degree the measured performance values match those taken from the simulation.

Marinaro, Ralph↗
DOE OSTI2020

Structural trends in atomic nuclei from laser spectroscopy of tin

Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2 + , 3/2 + , and 11/2 - states in 117–131 Sn, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Vertical Architecture Solution-Processed Quantum Dot Photodetectors with Amorphous Selenium Hole Transport Layer

Colloidal quantum dots (CQDs) provide wide spectral tunability and high absorption coefficients owing to quantum confinement and large oscillator strengths, which along with solution processability, allow a facile, low-cost, and room-temperature deposition technique for the fabrication of photonic devices. However, many solution-processed CQD photodetector devices demonstrate low specific-detectivity and slow temporal response. To achieve improved photodetector characteristics, limiting carrier recombination and enhancing photogenerated carrier separation are crucial. In this study, we develop and present an alternate vertical-stack photodetector wherein we use a solution-processed quantum dot photoconversion layer coupled to an amorphous selenium (a-Se) wide-bandgap charge transport layer that is capable of exhibiting single-carrier hole impact ionization and is compatible with active-matrix readout circuitry. This a-Se chalcogenide transport layer enables the fabrication of high-performance and reliable solution-processed quantum dot photodetectors, with enhanced charge extraction capabilities, high specific detectivity (D* ~ 0.5–5 × 10 12 Jones), fast 3 dB electrical bandwidth (3 dB BW ~ 22 MHz), low dark current density (J D ~ 5–10 pA/cm 2 ), low noise current (i n ~ 20–25 fW/Hz 1/2 ), and high linear dynamic range (LDR ~130–150 dB) across the measured visible electromagnetic spectrum (~405–656 nm).

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

On the Relative Strength of Electric and Magnetic ULF Wave Radial Diffusion During the March 2015 Geomagnetic Storm

In this paper, we study electron radial diffusion coefficients derived from Pc4-Pc5 ultralow frequency (ULF) wave power during the intense geomagnetic storm on 17–18 March 2015. During this storm the population of highly relativistic electrons was depleted within 2 hr of the storm commencement. This radial diffusion, depending upon the availability of source populations, can cause outward radial diffusion of particles and their loss to the magnetosheath, or inward transport and acceleration. Analysis of electromagnetic field measurements from Geostationary Operational Environment Satellite (GOES), Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite, and ground-based magnetometers shows that the main phase storm-specific radial diffusion coefficients do not correspond to statistical estimates. Specifically, during the main phase, the electric diffusion ($D^{E}_{LL}$) is reduced, and the magnetic diffusion ($D^{B}_{LL}$) is increased, compared to empirical models based on Kp . Contrary to prior results, the main phase magnetic radial diffusion cannot be neglected. The largest discrepancies, and periods of dominance of $D^{B}_{LL}$ over $D^{E}_{LL}$, occur during intervals of strongly southward IMF. However, during storm recovery, both magnetic and electric diffusion rates are consistent with empirical estimates. Here, we further verify observationally, for the first time, an energy coherence for both $D^{B}_{LL}$ and $D^{E}_{LL}$ where diffusion coefficients do not depend on energy. We show that, at least for this storm, properly characterizing main phase radial diffusion, potentially associated with enhanced ULF wave magnetopause shadowing losses, cannot be done with standard empirical models. Modifications, associated especially with southward IMF, which enhance the effects of $D^{B}_{LL}$ and introduce larger main phase outward transport losses, are needed.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Parameters of the Lightning Attachment Processes in a Negative Cloud-To-Ground Stroke Observed on a Microsecond Timescale

We present time-correlated ultra-high-speed video camera and electromagnetic field measurements of the attachment processes in a natural negative cloud-to-ground stroke. The video camera frame exposure time and pixel resolution were 740 ns and 0.91 m/pixel, respectively. The common streamer zone (CSZ) was first observed 2.52 µs preceding the first frame showing the return stroke (RS) in progress, when the upward and downward leader-tips were 9.8 m apart. In the next frame, the two leaders were observed to have propagated toward each other within the CSZ, with their tips being 0.91 m apart. Our observations show with unprecedented precision/clarity that (a) the slow front in the field waveform is associated with the CSZ, and (b) the “proper” start of the RS is marked by the onset of the fast transition in the field waveform which occurs at the completion of the attachment processes (when the upward and downward leaders have merged).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Advances in High-Power Wireless Charging Systems: Overview and Design Considerations

Wireless charging systems are foreseen as an effective solution to improve the convenience and safety of conventional conductive chargers. As this technology has matured, recent broad applications of wireless chargers to electrified transportation have indicated a trend toward higher power, power density, modularity, and scalability of designs. In this article, commercial systems and laboratory prototypes are reviewed, focusing mostly on the advances in high-power wireless charging systems. The recent endeavors in magnetic pad designs, compensation networks, power electronics converters, control strategies, and communication protocols are illustrated. Both stationary and dynamic (in-motion) wireless charging systems are discussed, and critical differences in their designs and applications are emphasized. On that basis, the comparisons among different solutions and design considerations are summarized to present the essential elements and technology roadmap that will be necessary to support large-scale deployment of high-power wireless charging systems. The review is concluded with the discussion of several fundamental challenges and prospects of high-power wireless power transfer (WPT) systems. Foreseen challenges include utilization of advanced materials, electric and electromagnetic field measurement and mitigation, customization, communications, power metering, and cybersecurity.

25 ENERGY STORAGE↗
DOE OSTI2018

Jefferson Lab at 12 GeV: The Science Program

Jefferson Lab’s upgrade of its Continuous Electron Beam Accelerator Facility (CEBAF) has recently been completed. The project involved an upgrade of the accelerator to achieve a maximum beam energy of 12 GeV and the construction of a fourth end station, Experimental Hall D, as well as new detector equipment for two of the three existing halls (A, B, and C). A broad experimental program has been developed to map the nucleon’s intrinsic quark distributions in transverse space and in longitudinal momentum through measurements of deeply exclusive and semi-inclusive processes, and to probe color confinement by studying the spectrum of hadrons with active gluon degrees of freedom in the wave function. Other programs include the forward parton distribution function at large quark momentum fraction χ, the quark and gluon polarized distribution functions, measurements of electromagnetic form factors of the nucleon ground state and of nucleon resonance transitions at short distances, and the exploration of physics beyond the Standard Model in high-precision parity-violating processes and in the search for signals of dark matter. The higher beam energy is also suitable for exploration of quark hadronization properties using the nucleus as a laboratory. This review highlights major areas of hadron and nuclear science that will be the focus of the first 5 years of operation.

3D imaging↗
DOE OSTI2019

The LLNL Program in Nuclear Structure and Nuclear Astrophysics (NSNA) (FY19 Annual Report)

Our major efforts in FY18-19 were devoted to carrying out the second GRETINA/CHICO2 campaign at ANL and the JANUS campaign at MSU/NSCL. Among a total of 13 fielded experiments, three were for Ph.D. thesis projects; two students at MSU and one at UNC at Chapel Hill. Two experiments in the JANUS campaign were led by LLNL; namely, the study of nuclear structure in 72 Se and 76 Se using the sub-barrier Coulomb excitation method. The data analysis was completed for both selenium isotopes and the results were published. The 72 Se results have been submitted to DOE/SC/NP as a science highlight and the article won a prestigious LLNL S&T Excellence in Publication Award in FY19. For experiments fielded in FY17 at TRIUMF/ISAC2 using TIGRESS/Bambino, the data analysis was completed recently and the 21 Mg results were published in FY19. For the results on the mirror nuclei 23 Mg and 23 Na, the manuscript was written and is in circulation among the coauthors. We intend to submit it for publication later this calendar year. These efforts address the isospin symmetry in the sd shell nuclei in terms of the electromagnetic properties measured with the sub-barrier Coulomb excitation method. The proposal to upgrade CHICO2 to CHICOX by resizing the detector chamber to be compatible to GRETA was approved in FY17 with a budget spread over three fiscal years starting FY18. The preliminary design was completed but cannot be finalized until the design for the GRETA holding frame is completed by the LBNL GRETA team in FY19. The fabrication will proceed once the physical compatibility of CHICOX to GRETA holding frame is confirmed. The narrative below focuses on the research efforts for which LLNL led or played a key role. This report includes two sections: 1) Evolution of shell structure and collectivity in neutron-rich nuclei, and 2) Investigating nucleosynthesis and the Standard Model with β decay.

42 ENGINEERING↗
DOE OSTI2024

A multi-Physics Experiment for Low-Yield Nuclear Explosion Monitoring

A series of multi-physics experiments, referred to as Physics Experiment 1 (PE1) is underway at the United States’ Nevada National Security Site (NNSS). The PE1 series includes detonations of three underground chemical explosions in P-tunnel, with fully coupled (PE1 A), partially decoupled (PE1 D L ), and fully decoupled (PE1 B) emplacements. Canisters with gas tracers are imbedded in the explosives, and the tracers are released when the canister is destroyed by the detonation. A dedicated electromagnetic (EM) experiment (EMX) generates well-characterized EM signals at an underground location near the chemical explosive experiments. A series of atmospheric experiments (METEX, REACT, and METREX) release smoke and radioactive tracers around Aqueduct Mesa to test gas transport in complex topography. Each of the chemical explosive experiments includes a network of sensors to record seismic, acoustic, and electromagnetic waves, measurement of atmospheric conditions, and air sample collection for measurement of tracer concentration. EMX records EM signals underground and on the surface of Aqueduct Mesa. METEX, REACT, and METREX include measurement of atmospheric condition, as well as tracking smoke releases. REACT and METREX add low-level radioactive gas tracers to the atmospheric releases.

58 GEOSCIENCES↗
DOE OSTI2026

Impact of Annealing on Superconducting Properties of Tantalum Thin Films

The pursuit for higher-coherence superconducting qubits has led to the adoption of new materials and innovative fabrication techniques. Among the commonly used superconducting materials, tantalum-based or tantalum-capped superconducting qubits have demonstrated the longest lifetimes, outperforming niobium devices even in the presence of their native oxides. Given the losses introduced by the surface oxide, one method to further improve performance is to reduce or eliminate the native oxide on tantalum through UHV annealing. In this work, we examine the effect of dissolved oxygen as a function of annealing temperature on the superconducting properties of tantalum thin films. Dissolved oxygen is quantified using atom probe tomography (APT) and secondary ion mass spectrometry (TOF-SIMS) and correlated with electromagnetic transport measurements performed using a Physical Property Measurement System (PPMS). This study observes that annealing decomposes the native oxide and drives oxygen diffusion into the film matrix. Increasing oxygen content decreases the superconducting transition temperature (Tc) and the residual resistivity ratio (RRR). The critical field decreases with the incorporation of oxygen, while the film’s coherence length decreases relatively by 5%. These results, as well as findings from ongoing studies linking fabrication processes to the structural and chemical properties of the superconducting film and Josephson junction, provide insight into effective strategies for improving the performance of superconducting devices.

Shinde, Maithilee [IIT, Chicago; Fermilab]↗
DOE OSTI2021

Measurement of Parity Violating Asymmetry in Elastic Electron Scattering off 48Ca

Atomic nuclei are composed of nucleons governed by the strong nuclear force. Although the proton distributions in nuclei are well measured with electromagnetic probes, the neutron distributions are relatively unconstrained. The nuclear symmetry energy governs the distribution of the excess neutrons in asymmetric nuclei, as well as the dynamics of neutron-rich nuclear matter up to the scale of neutron stars….

Clarke, Cameron↗