Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “form factor”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Overview of Nucleon Form Factor Experiments with 12 GeV at Jefferson Lab

Since the R. Hofstadter pioneering experiments in the '50s, the measurements of the electromagnetic space-like nucleon form factors (FF's) have been a precious source of information for the understanding of the internal structure of the nucleons. In the last 15 years, the polarization transfer experiments at the Thomas Jefferson National Accelerator Facility (JLab) have undermined our view of the mechanism of the electron scattering and renewed critical interest in the FF measurements. In the coming years, JLab, with its upgraded 12 GeV polarized, high intensity, electron beam combined to new targets and readout equipments, will offer unprecedented opportunities to extend the current proton and neutron FF's measurements to higher momentum transfer Q{sup 2} and to improve statistical and uncertainties at lower Q{sup 2}, where the nucleon size can be accurately investigated. The measurements at high Q{sup 2} will provide also new insights on the elusive quark orbital angular momenta, will contribute to constraint two of the nucleon Generalized Parton Distributions that are expected to describe more consistently the nucleon structure, and in general will test the validity of quite a few fundamental nucleon models in a region of transition between perturbative and non perturbative regimes. A selection of the relevant properties of the FF's, and the main results of JLab are shortly reviewed; the new proposed and approved experiments on FF's at JLab are presented addressing some key details, the expected experimental achievements and the new equipment designed for them.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Generalized parton distributions and gravitational form factors at large momentum transfer

Within the soft collinear effective theory (SCET), we derive a factorization theorem which resums Sudakov logarithms (α s ln 2 ( –t)) n to all orders in the quark-in-quark generalized parton distribution (GPD) at large momentum transfer t, and perform a consistency check to one-loop. We show that the same Sudakov factor appears in the ‘Feynman’ contribution to the GPDs of the nucleon. Our result enables the resummation of all the large logarithms ln Q 2 and ln 2 t in exclusive processes with two hard scales Λ$^{2}_{QCD}$ ≪ |t| ≪ Q 2 . We also present a SCET power counting analysis of the Feynman contributions to the GPDs and show that the x-dependence of GPDs factorizes at large-t with controlled corrections. This in particular implies that any ratio of GPD moments such as the electromagnetic and gravitational form factors (GFF) is perturbatively calculable in this approximation. Furthermore, we identify a novel order α s power-law t-dependence in the GPD and the D-type GFF that will dominate over the standard order α$^{2}_{s}$ ‘leading twist’ asymptotic contribution in the phenomenologically relevant region of t.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2019

Design and Testing of the CubeSat Form Factor Thermal Control Louvers

As CubeSat and SmallSat missions increase in complexity and power consumption they present innate thermal challenges. Science instruments may require thermal stability while a variety of factors such as high-powered components, sunlight and shadow on orbit, or tight spacecraft layout may produce a wide range of temperatures. The CubeSat Form Factor Thermal Control Louvers are a passive method of stabilizing the thermal environment inside of small spacecraft via miniature thermal louvers. These louvers are a patented design, with a technology demonstration version of the louvers operating correctly in flight on the Dellingr CubeSat in 2018. This paper will describe the methods used to develop and test this technology, as well as the results obtained and how this technology may be used in CubeSat and SmallSat missions.

louvers↗
DOE OSTI2026

Calculation of nuclear magnetic form factors [Slides]

The knowledge of how electron and neutrinos interact in nuclei is critical to an understanding of finite nucle and of astrophysical environments like neutron stars and supernovae. Within this project we are studying nuclear magnetic form factors that reflect how electrons interact with nuclei at low momenta. We implemented realistic treatments of many-nucleon correlations and currents to enable high-precision studies of electron physics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Precise Measurement of the Neutron Magnetic Form Factor Using Super-BigBite Spectrometer at Jefferson Lab

The GMn experiment (E12-09-019) was conducted at Jefferson Laboratory from late 2021 into early 2022. The goal was to make high-precision measurement of the neutron’s magnetic form factor (GMn) at multiple kinematic points, including Q2 = 3.5, 4.5, 6.5, 8.5, 10, 12, 13.5, 16, and 18 (GeV/c)2. Limited data exist for GMn in the region up to about Q2 = 10 (GeV/c)2, with existing data having large systematic uncertainty. In this experiment, the ratio method was employed to reduce systematic uncertainty by measuring the ratio of neutron and proton yields. The experiment took place at Jefferson Laboratory in Hall A, where the BigBite spectrometer was used to detect the scattered electrons, while the HCal in the SuperBigbite spectrometer was used to detect both neutrons and protons. The protons were deflected slightly upwards with the use of a large-aperture dipole magnet named BigBen, allowing for enhanced particle identification. Extraction of GMn requires taking the ratio of proton and neutron yields. Analysis efforts are still currently underway to refine corrections to the data, including detector efficiencies, radiative corrections, neutron and proton mass identification, and charge exchange.

Lashley-Colthirst, Nathaniel↗
DOE OSTI2026

Extracting $B_s\to D_s^*\ellν_\ell$ form factors

Semileptonic $B_{(s)}$ decays are of great phenomenological interest because they allow to determine e.g. CKM matrix elements or test lepton flavor universality. Taking advantage of already existing lattice data, we demonstrate the analysis steps to extract the four form factors describing exclusive semileptonic $B_s\to D_s^*\ellν_\ell$ decays using the narrow width approximation. Our data are based on RBC/UKQCD's set of 2+1 flavor gauge field ensembles with Shamir domain-wall fermion and Iwasaki gauge field action featuring inverse lattice spacings of $a^{-1}=$1.785, 2.383, and 2.785 GeV as well as pion masses between 268 and 433 MeV. Light, strange and charm quarks are simulated using domain-wall fermions, whereas bottom quarks are generated with the relativistic heavy quark (RHQ) action.

Boushmelev, Anastasia [Siegen U.] (ORCID:000000033↗
DOE OSTI2016

Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD

We study the exclusive semileptonic B-meson decays B→K(π)ℓ + ℓ - , B→K(π)νν¯, and B→πτν, computing observables in the Standard model using the recent lattice-QCD results for the underlying form factors from the Fermilab Lattice and MILC Collaborations. These processes provide theoretically clean windows into physics beyond the Standard Model because the hadronic uncertainties are now under good control. The resulting partially-integrated branching fractions for B→πμ + μ - and B→Kμ + μ - outside the charmonium resonance region are 1-2σ higher than the LHCb Collaboration's recent measurements, where the theoretical and experimental errors are commensurate. The combined tension is 1.7σ. Combining the Standard-Model rates with LHCb's measurements yields values for the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements |V td |=7.45(69)×10 -3 , |V ts |=35.7(1.5)×10 -3 , and |V td /V ts |=0.201(20), which are compatible with the values obtained from neutral B (s) -meson oscillations and have competitive uncertainties. Alternatively, taking the CKM matrix elements from unitarity, we constrain new-physics contributions at the electroweak scale. Furthermore, the constraints on the Wilson coefficients Re(C 9 ) and Re(C 10 ) from B→πμ + μ - and B→Kμ + μ - are competitive with those from B→K*μ + μ - , and display a 2.0σ tension with the Standard Model. Our predictions for B→K(π)νν¯ and B→πτν are close to the current experimental limits.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Meson Form Factors and Deep Exclusive Meson Production Experiments

Pion and kaon electroproduction data play a unique role in Nature and our understanding of them is essential for explaining hadron structure. Precision longitudinaltransverse separated pion and kaon cross sections are of particular interest. They allow for the extraction of meson form factors and validation of understanding of hard exclusive and semi-inclusive reactions (π+, K+, π0, γ) towards 3D hadron imaging and potential future flavor decomposition. We review recent data and present prospects for deep exclusive pion and kaon electroproduction at the 12 GeV Jefferson Lab including the prospects to use projected charged- and neutral pion data to further determine the spin, charge-parity and flavor of GPDs, including the helicity-flip GPDs.

Horn, Tanja↗
DOE OSTI2018

New Methods for B Decay Constants and Form Factors from Lattice NRQCD

We determine the normalisation of scalar and pseudo scalar current operators made from NonRelativistic QCD (NRQCD) b quarks and Highly Improved Staggered (HISQ) light quarks through O(α s Λ QCD /m b ). We use matrix elements of these operators to extract B meson decay constants and form factors and compare to those obtained using the standard vector and axial vector operators. We work on MILC second-generation 2+1+1 gluon field configurations, including those with physical light quarks in the sea. This provides a test of systematic uncertainties in these calculations and we find agreement between the results to the 2% level of uncertainty previously quoted.

Davies, Christine↗
DOE OSTI2023

Monte Carlo simulation of shielding designs for a cabinet form factor preclinical MV–energy photon FLASH radiotherapy system

Purpose: A preclinical MV-energy photon FLASH radiotherapy system is being designed at Stanford and SLAC National Accelerator Laboratory. Because of the higher energy and dose rate compared to conventional kV-energy photon laboratory-scale irradiators, adequate shielding in a stand-alone cabinet form factor is more challenging to achieve. We present a Monte Carlo simulation of multilayered shielding for a compact self-shielding system without the need for a radiation therapy vault. Methods: A multilayered shielding approach using multiple alternating layers of high-Z and low-Z materials is applied to the self-shielded cabinet to effectively mitigate the secondary radiation produced and to allow the device to be housed in a Controlled Radiation Area outside of a radiation vault. The multilayered shielding approach takes advantage of the properties of high-Z and low-Z radiation shielding materials such as density, cross-section, atomic number of the shielding elements, and products of radiation interactions within each layer. The Monte Carlo radiation transport code, FLUKA, is used to simulate the total effective dose produced by the operation. Results: The multilayered shielding designs proposed and simulated produced effective dose rates significantly lower than monolayer designs with the same total material thickness at the regulatory boundary; this is accomplished through the manipulation of the locations where secondary radiation is produced and reactions due to material properties such as neutron back reflection in hydrogen. Borated polyethylene at 5 wt% significantly increased the shielding performance as compared to regular polyethylene, with the magnitude of the reduction depending upon the order of the shielding material. Conclusions: The multilayered shielding provides a path for shielding preclinical FLASH systems that deliver MV-energy bremsstrahlung photons. Furthermore, this approach promises to be more efficient with respect to the shielding material mass and space claim as compared to shielded vaults typically required for clinical radiation therapy with MV photons.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Efficient Application of the Factorized form of the Unitary Coupled-Cluster Ansatz for the Variational Quantum Eigensolver Algorithm by Using Linear Combination of Unitaries

The variational quantum eigensolver is one of the most promising algorithms for near-term quantum computers. It has the potential to solve quantum chemistry problems involving strongly correlated electrons with relatively low-depth circuits, which are otherwise difficult to solve on classical computers. The variational eigenstate is constructed from a number of factorized unitary coupled-cluster terms applied onto an initial (single-reference) state. Current algorithms for applying one of these operators to a quantum state require a number of operations that scale exponentially with the rank of the operator. We exploit a hidden SU(2) symmetry to allow us to employ the linear combination of unitaries approach, Our Prepare subroutine uses n+2 ancilla qubits for a rank-n operator. Our Select (U) scheme uses O(n) Cnot gates. This results in a full algorithm that scales like the cube of the rank of the operator n 3 , a significant reduction in complexity for rank five or higher operators. This approach, when combined with other algorithms for lower-rank operators (when compared to the standard implementation), will make the factorized form of the unitary coupled-cluster approach much more efficient to implement on all types of quantum computers.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

Scattering from phase-separated vesicles. I. An analytical form factor for multiple static domains

This is the first in a series of studies considering elastic scattering from laterally heterogeneous lipid vesicles containing multiple domains. Unique among biophysical tools, small-angle neutron scattering can in principle give detailed information about the size, shape and spatial arrangement of domains. A general theory for scattering from laterally heterogeneous vesicles is presented, and the analytical form factor for static domains with arbitrary spatial configuration is derived, including a simplification for uniformly sized round domains. The validity of the model, including series truncation effects, is assessed by comparison with simulated data obtained from a Monte Carlo method. Several aspects of the analytical solution for scattering intensity are discussed in the context of small-angle neutron scattering data, including the effect of varying domain size and number, as well as solvent contrast. Finally, the analysis indicates that effects of domain formation are most pronounced when the vesicle's average scattering length density matches that of the surrounding solvent.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Measurements of Σ electromagnetic form factors in the timelike region using the untagged initial-state radiation technique

The process e + e − → Σ + Σ ¯ − is studied from threshold up to 3.04 GeV / c 2 via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb − 1 , collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of Σ are measured in eleven Σ + Σ ¯ − invariant mass intervals from threshold to 3.04 GeV / c 2 . The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J / ψ → Σ + Σ ¯ − and ψ ( 3686 ) → Σ + Σ ¯ − are determined and the obtained results are consistent with the previous results of BESIII. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2023

FLArE up dark sectors with EM form factors at the LHC forward physics facility

Despite being mostly secluded, dark sector particles may feebly interact with photons via a small mass-dimension 4 millicharge, a mass-dimension 5 magnetic and electric dipole moment, or a mass-dimension 6 anapole moment and charge radius. If sufficiently light, the LHC may produce an intense and collimated beam of these particles in the far forward direction. We study the prospects of searching for such dark sector particles with electromagnetic form factors via their electron scattering signature in the Forward Liquid Argon Experiment (FLArE) at the Forward Physics Facility (FPF). We find that FLArE can provide new probes of sub-GeV dark particles with dipole moments and strong sensitivities for millicharged particles in the 100 MeV to 100 GeV region. This complements other search strategies using scintillation signatures or dark matter direct detection and allows for probing strongly interacting dark matter motivated by the EDGES anomaly. Along with the FORMOSA detector, this leads to a very versatile and leading experimental program in the search for millicharged particles in the FPF.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Transition Form Factors via Lattice QCD

Lattice QCD has proven to be a fully predictive tool for studying low-energy hadronic physics directly from QCD. There are a number of matrix elements involving hadronic two-body initial and/or final states for which a lattice QCD calculation would lead to significant advancement for nuclear and particle physics, e.g., parity violation in the nuclear sector. In this talk I address challenges associated with studying observables for processes involving two particles or more, and I present a framework for studying one-to-two transition form factors.

Briceno, Raul↗
DOE OSTI2017

Exposing strangeness: Projections for kaon electromagnetic form factors

A continuum approach to the kaon and pion bound-state problems is used to reveal their electromagnetic structure. For both systems, when used with parton distribution amplitudes appropriate to the scale of the experiment, Standard Model hard-scattering formulas are accurate to within 25% at momentum transfers Q 2 ≈ 8 GeV 2 . There are measurable differences between the distribution of strange and normal matter within the kaons, e.g. the ratio of their separate contributions reaches a peak value of 1.5 at Q 2 ≈ 6 GeV 2 . Its subsequent Q 2 evolution is accurately described by the hard scattering formulas. Projections for the ratio of kaon and pion form factors at timelike momenta beyond the resonance region are also presented. In conclusion, these results and projections should prove useful in planning next-generation experiments.

74 ATOMIC AND MOLECULAR PHYSICS↗