Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Experimental particle physics”

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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Dynamics and Structure of Weakly-Strained Flames In Normal- and Micro-Gravity

Strained laminar flames have been systematically studied, as the understanding of their structure and dynamic behavior is of relevance to turbulent combustion. Most of these studies have been conducted in opposed-jet, stagnation-type flow configurations. Flame studies in stagnation flows also allow for the determination of fundamental flame properties such as laminar flame speeds and extinction states that can be also conveniently modeled in detail. Studies at high strain rates are important in quantifying and understanding the response of vigorously-burning flames under conditions in which the transport time scales become comparable to the chemical time scales. Studies of weakly-strained flames can be of particular interest for all stoichiometries. For example, the laminar flame speeds for any equivalence ratio, phi, can be accurately determined by using the counterflow technique only if measurements are obtained at very low strain rates. Furthermore, near-limit flames can be only stabilized by weak strain rates. Previous studies have shown that weakly-burning flames are particularly sensitive to chain mechanisms, thermal radiation, and unsteadiness. The stabilization and study of weakly-strained flames is complicated by the presence of buoyancy that can render the flames unstable to the point of extinction. Such instabilities are caused either by the induced natural convection or the fact that higher density fluid can find itself on top of a lower density fluid. Thus, the use of microgravity (mu-g) becomes essential in order to provide meaningful insight into this important combustion regime. In view of the foregoing considerations, the main objectives of the program are to: (1) Experimentally determine the laminar flame speed at near-zero strain rates; (2) Experimentally determine the extinction limits of near-limit flames; (3) Experimentally determine the response of near-limit flames to unsteadiness and heat loss; (4) Introduce Digital Particle Image Velocimetry (DPIV) in microgravity; (5) Conduct detailed numerical simulations of the experiments; and (6) Provide physical insight into the underlying physico-chemical mechanisms.

Zhang, Hai↗
NASA NTRS2001

Heterogenous Combustion of Porous Graphite Particles in Normal and Microgravity

Combustion of solid fuel particles has many important applications, including power generation and space propulsion systems. The current models available for describing the combustion process of these particles, especially porous solid particles, include various simplifying approximations. One of the most limiting approximations is the lumping of the physical properties of the porous fuel with the heterogeneous chemical reaction rate constants. The primary objective of the present work is to develop a rigorous model that could decouple such physical and chemical effects from the global heterogeneous reaction rates. For the purpose of validating this model, experiments with porous graphite particles of varying sizes and porosity are being performed. The details of this experimental and theoretical model development effort are described.

Chelliah, Harsha K.↗
DOE OSTI2022

DarkQuest: A dark sector upgrade to SpinQuest at the 120 GeV Fermilab Main Injector

Expanding the mass range and techniques by which we search for dark matter is an important part of the worldwide particle physics program. Accelerator-based searches for dark matter and dark sector particles are a uniquely compelling part of this program as a way to both create and detect dark matter in the laboratory and explore the dark sector by searching for mediators and excited dark matter particles. This paper focuses on developing the DarkQuest experimental concept and gives an outlook on related enhancements collectively referred to as LongQuest. DarkQuest is a proton fixed-target experiment with leading sensitivity to an array of visible dark sector signatures in the MeV-GeV mass range. Because it builds off of existing accelerator and detector infrastructure, it offers a powerful but modest-cost experimental initiative that can be realized on a short timescale.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Quasiparticle electronic structure of phthalocyanine:TMD interfaces from first-principles GW

Interfaces formed between monolayer transition metal dichalcogenides and (metallo)phthalocyanine molecules are promising in energy applications and provide a platform for studying mixed-dimensional molecule-semiconductor heterostructures in general. An accurate characterization of the frontier energy level alignment at these interfaces is key in the fundamental understanding of the charge transfer dynamics between the two photon absorbers. Here, we employ the first-principles substrate screening GW approach to quantitatively characterize the quasiparticle electronic structure of a series of interfaces: metal-free phthalocyanine (H 2 Pc) adsorbed on monolayer MX 2 (M = Mo, W; X = S, Se) and zinc phthalocyanine (ZnPc) adsorbed on MoX 2 (X = S, Se). Furthermore, we reveal the dielectric screening effect of the commonly used α-quartz (SiO 2 ) substrate on the H 2 Pc:MoS 2 interface using the dielectric embedding GW approach. Our calculations furnish a systematic set of GW results for these interfaces, providing the structure–property relationship across a series of similar systems and benchmarks for future experimental and theoretical studies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Stratospheric aerosols - Observation and theory

Important chemical and physical roles of aerosols are discussed, and properties of stratospheric aerosols as revealed by experimental data are described. In situ measurements obtained by mechanical collection and scattered-light detection yield the overall size distribution of the aerosols, and analyses of preserved aerosol precursor gases by wet chemical, cryogenic and spectroscopic techniques indicate the photochemical sources of particle mass. Aerosol chemical reactions including those of gaseous precursors, those in aqueous solution, and those on particle surfaces are discussed, in addition to aerosol microphysical processes such as nucleation, condensation/evaporation, coagulation and sedimentation. Models of aerosols incorporating such chemical and physical processes are presented, and simulations are shown to agree with measurements. Estimates are presented for the potential aerosol changes due to emission of particles and gases by aerospace operations and industrial consumption of fossil fuels, and it is demonstrated that although the climatic effects of existing levels of stratospheric aerosol pollution are negligible, potential increases in those levels might pose a future threat.

Turco, R. P.↗
DOE OSTI2024

Effective theory tower for μ → e conversion

We present theoretical predictions for μ → e conversion rates using a tower of effective field theories connecting the UV to nuclear physics scales. The interactions in nuclei are described using a recently developed nonrelativistic effective theory (NRET) that organizes contributions according to bound nucleon and muon velocities, ${\overrightarrow{v}}_N$ and ${\overrightarrow{v}}_μ$, with |${\overrightarrow{v}}_N$| > |${\overrightarrow{v}}_μ$|. To facilitate the top-down matching, we enlarge the set of Lorentz covariant nucleon-level interactions mapped onto the NRET operators to include those mediated by tensor interactions, in addition to the scalar and vector interactions already considered previously, and then match NRET nonperturbatively onto the Weak Effective Theory (WET). At the scale μ ≈ 2 GeV WET is formulated in terms of u, d, s quarks, gluons and photons as the light degrees of freedom, along with the flavor-violating leptonic current. We retain contributions from WET operators up to dimension 7, which requires the full set of 26 NRET operators. The results are encoded in the open-source Python- and Mathematica-based software suite MuonBridge, which we make available to the theoretical and experimental communities interested in μ → e conversion.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Status on lattice calculations of the proton spin decomposition

Abstract Lattice calculations of the proton spin components is reviewed. The lattice results of the quark spin from the axial-vector current matrix element at ∼ 0.3−0.4 is smaller than those from the constituent quark models. This is largely due to the fact that the vacuum polarization contribution from the disconnected insertion is negative. Its connection with the anomalous Ward identity is clarified and verified numerically. This resolves the contentious issue in the “proton spin crisis.” The glue spin and angular momentum are found to be large and there is notable contribution from the quark orbital angular momentum. Renormalization, mixing, and normalization of the quark and glue angular momenta are discussed. With sufficient precision, they can be compared with more precise experimental measurements when the electron-ion collider facility is available.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Photon-triggered jets as probes of multi-stage jet modification

Prompt photons are created in the early stages of heavy ion collisions and traverse the QGP medium without any interaction. Therefore, photontriggered jets can be used to study the jet quenching in the QGP medium. In this work, photon-triggered jets are studied through different jet and jet substructure observables for different collision systems and energies using the JETSCAPE framework. Since the multistage evolution used in the JETSCAPE framework is adequate to describe a wide range of experimental observables simultaneously using the same parameter tune, we use the same parameters tuned for jet and leading hadron studies. The same isolation criteria used in the experimental analysis are used to identify prompt photons for better comparison. For the first time, high-accuracy JETSCAPE results are compared with multi-energy LHC and RHIC measurements to better understand the deviations observed in prior studies. This study highlights the importance of multistage evolution for the simultaneous description of experimental observables through different collision systems and energies using a single parameter tune.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Theoretical status of ε '/ε

We briefly overview the historical controversy around Standard Model predictions of ε '/ε and clarify the underlying physics. A full update of this important observable is presented, with all known short- and long-distance contributions, including isospin-breaking corrections. The current Standard Model prediction, Re(ε '/ε) = (14 ± 5) centerdot 10 –4 [1, 2], is in excellent agreement with the experimentally measured value.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Performance of a ton-scale water-based liquid scintillator detector

This study reports the performance and light yield of 1% concentration water-based liquid scintillator (WbLS) deployed in a 1000-liter detector. A light yield of 99± 15 photons per MeV is determined by comparing data with simulation. This result aligns with our previous light yield determination using smaller detectors, thus establishing a solid foundation for the ongoing development and deployment of WbLS in larger-scale detectors. In conclusion, the feasibility of in situ preparation and the stability of light yield in WbLS are demonstrated, reinforcing its suitability for long-term experimental endeavors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Introducing Tunes in Geant4 Hadronic Models

The talk will give an overview of tuning Geant4 model parameters via fits of simulated distributions to the experimental thin target data, and will introduce the concept of "tunes" in Geant4 hadronic models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Proton Electric Charge Radius from Lepton Scattering

A proton is a bound state of a strong interaction, governed by Quantum Chromodynamics (QCD). The electric charge radius of a proton, denoted by $r^{p}_{E}$, characterizes the spatial distribution of its electric charge carried by the quarks. It is an important input for bound-state Quantum Electrodynamic (QED) calculations of the hydrogen atomic energy levels. However, physicists have been puzzled by the large discrepancy between $r^{p}_{E}$ measurements from muonic hydrogen spectroscopy and those from ep elastic scattering and ordinary hydrogen spectroscopy for over a decade. Tremendous efforts, both theoretical and experimental, have been dedicated to providing various insights into this puzzle, but certain issues still remain unresolved, particularly in the field of lepton scatterings. This review will focus on lepton-scattering measurements of $r^{p}_{E}$, recent theoretical and experimental developments in this field, as well as future experiments using this technique.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Checking nonflow assumptions and results via PHENIX published correlations in p+p, p+Au, d+Au, and 3 He+Au at √ s NN=200 GeV

Recently the PHENIX Collaboration has made available two-particle correlation Fourier coefficients for multiple detector combinations in minimum bias p+p and 0–5% central p+Au, d+Au, and 3 He+Au collisions at √ s NN = 200 GeV [Phys. Rev. C 105, 024901 (2022)]. Using these coefficients for three sets of two-particle correlations, azimuthal anisotropy coefficients v 2 and v 3 are extracted for midrapidity charged hadrons as a function of transverse momentum. In this paper, we use the available coefficients to explore various nonflow hypotheses as well as to compare the results with theoretical model calculations. The nonflow methods fail basic closure tests with ampt and pythia/angantyr, particularly when including correlations with particles in the low multiplicity light-projectile going direction. In data, the nonflow adjusted v 2 results are modestly lower in p+Au and the adjusted v 3 results are more significantly higher in p+Au and d+Au. However, the resulting higher values for the ratio v 3 /v 2 in p+Au at RHIC compared to p+Pb at the LHC is additional evidence for a significant overcorrection. Incorporating these additional checks, the conclusion that these flow coefficients are dominated by initial geometry coupled with final-state interactions (e.g., hydrodynamic expansion of quark-gluon plasma) remains true, and explanations based solely on initial-state glasma are ruled out. The detailed balance between intrinsic and fluctuation-driven geometry and the exact role of weakly versus strongly coupled prehydrodynamic evolution remains an open question for triangular flow, requiring further theoretical and experimental investigation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1984

Experiments on water/melt explosions, nature of products, and models of dispersal

Experiments were carried out in a steel pressure device using controlled amounts of water and thermite melt to examine the mechanical energy released on explosive mixing following the initial contact of the two materials. An experimental design was used to allow the direct calculation of the mechanical energy by the dynamic lift of the device as recorded both optically and physically. A large number of experiments were run to accurately determine the optimum mixture of water and melt for the conversion of thermal to mechanical energy. The maximum efficiency observed was about 12% at a water/thermite mass ratio of 0.50. These experiments are the basis for the development of models of hydroexplosions and melt fragmentation. Particles collected from the experimental products are similar in size and shape to pyroclasts produced by much larger hydrovolcanic explosions. Melt rupture at optimum ratios produces very fine particles whereas rupture at high or low water/melt ratios produces large melt fragments. Grain surface textures in the experimental products are also related to the water/melt ratio and the mechanism of explosive mixing. It is thus possible to have qualitative information about the nature of the explosion from the sizes and shapes of the fragments produced.

Sheridan, M. F.↗
DOE OSTI2022

First Measurement Of Charged-current 1 Muon 2 Proton 0 Pion Single Differential Cross-sections On Argon-40 At 0.8 Gev Average Neutrino Energy With The MicroBooNE Detector

Constraining systematic uncertainties that arise from neutrino-nucleon cross-section modeling is critical for upcoming neutrino oscillation experiments. Neutrino interactions that lead to the ejection of 2 particles from the target nucleus, leaving the nucleus with 2 holes, are one cross-section of interest. These instances, known as 2-particle 2-hole (2p2h) states, can be produced either by neutrino interaction modes or from the influence of nuclear physics on the neutrino interaction. While there are many theoretical models that attempt to describe the nature of 2p2h states, very few experimental measurements of this process exist, making it difficult to benchmark theoretical calculations. Furthermore, no high statistic cross-section measurements of 2p2h states exist on $^{40}$Ar, the target nucleus of many current and next generation neutrino oscillation experiments. This analysis aims to address this issue by providing the first high-statistic single differential cross-section me asurements of 2p2h states. Using data collected from the first 3 years of running of the MicroBooNE experiment, we select $\nu_\mu$ charged-current interaction events that produce a single muon, 2 protons, and no pions in the final state (CC1$\mu$2p0$\pi$). The single differential cross-section is then extracted as a function of a variety of physics variables and compared to theoretical predictions from several event generator model sets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

The Future of High Energy Physics Software and Computing (V2.1)

Software and Computing (S&C) are essential to all High Energy Physics (HEP) experiments and many theoretical studies. The size and complexity of S&C are now commensurate with that of experimental instruments, playing a critical role in experimental design, data acquisition/instrumental control, reconstruction, and analysis. Furthermore, S&C often plays a leading role in driving the precision of theoretical calculations and simulations. Within this central role in HEP, S&C has been immensely successful over the last decade. This report looks forward to the next decade and beyond, in the context of the 2021 Particle Physics Community Planning Exercise ("Snowmass") organized by the Division of Particles and Fields (DPF) of the American Physical Society.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗