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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Differential Cross Section Kinematics for 3-dimensional Transport Codes

In support of the development of 3-dimensional transport codes, this paper derives the relevant relativistic particle kinematic theory. Formulas are given for invariant, spectral and angular distributions in both the lab (spacecraft) and center of momentum frames, for collisions involving 2, 3 and n - body final states.

Norbury, John W.↗
NASA NTRS2014

Elastic Differential Cross Sections

The eikonal, partial wave (PW) Lippmann-Schwinger, and three-dimensional Lippmann-Schwinger (LS3D) methods are compared for nuclear reactions that are relevant for space radiation applications. Numerical convergence of the eikonal method is readily achieved when exact formulas of the optical potential are used for light nuclei (A less than or equal to 16) and the momentum-space optical potential is used for heavier nuclei. The PW solution method is known to be numerically unstable for systems that require a large number of partial waves, and, as a result, the LS3D method is employed. The effect of relativistic kinematics is studied with the PW and LS3D methods and is compared to eikonal results. It is recommended that the LS3D method be used for high energy nucleon- nucleus reactions and nucleus-nucleus reactions at all energies because of its rapid numerical convergence and stability.

Werneth, Charles M.↗
NASA NTRS2024

A Computationally Efficient Algorithm for Sampling the Rudd Differential Cross Section

Monte Carlo radiation transport codes such as RITRACKS or Geant4 are used to simulate the interaction of ions with matter. These codes rely on sampling algorithms to determine interactions and various physical properties of particles involved in the simulations. It is crucial to develop efficient sampling algorithms since Monte Carlo radiation transport simulations can be time consuming. This work presents an efficient sampling algorithm to determine the energy of secondary electrons following ion-water interactions. The applicability and intended use of the algorithm are discussed in detail, and it is shown that the new algorithm is up to 6X10 4 times faster than the method currently used in Geant4-DNA.

Floriane Poignant↗
NASA NTRS1985

Differential scattering cross sections for collisions of 0.5-, 1.5-, and 5.0-keV helium atoms with He, H2, N2, and O2

This paper reports the first results of an experimental program established to provide cross section data for use in modeling various atmospheric processes. Absolute cross sections, differential in the scattering angle, have been measured for collisions of 0.5-, 1.5-, and 5.0-keV helium atoms with He, H2, N2, and O2 at laboratory scattering angles between 0.1 deg and 5 deg. The results are the sums of cross sections for elastic and inelastic scattering of helium atoms; charged collision products are not detected. Integration of the differential cross section data yields integral cross sections consistent with measurements by other workers. The apparatus employs a position-sensitive detector for both primary and scattered particles and uses a short target cell with a large exit aperture to ensure a simple and well-defined apparatus geometry.

Newman, J. H.↗
DOE OSTI2022

Search for the NΔ resonance in the 𝛾𝑑 → 𝑑𝜋 +𝜋 − reaction

A dibaryon which is an object with baryon number B = 2 has been studied for a long time. Dyson and Xuong classified non-strangeness dibaryon states based on SU(6) symmetries in 1960?s. In the framework, the deuteron is classified as one of the sextet states of dibaryons. Although dibaryon have been an interesting subject of research for a long time, most of the experimental studies up to the early 2000?s were unsuccessful. The CELCIUS/WASA collaboration reported this state via the double-pionic fusion reaction (?= ! 3c0c0) in 2009. Thereafter, the WASA-at-COSY collaboration revealed properties of the isoscaler resonance state via the ?= ! 3c0c0 reaction in 2011. The dibaryon resonance state with isospin ? = 0 and spin ( = 3 thought to be a ?03 which was predicted by Dyson and Xuong at 2.35 GeV?22 with a configuration of ??. The reported mass and width of that state were 2?37 GeV?22 and 0?07 GeV?22, espectively. The mass was ?0?08 GeV?22 smaller than that of 2?, the width was narrower than that of single ?. This surprising result made dibaryon study come back into the limelight. ?12 is one of the dibaryon states classified by Dyson and Xuong with isospin ? = 1, spin ( = 2. This state can be regarded as an s-wave #? resonance. ?12 is an interesting state from the point of view of the possibilities of existence as an internal structure of ?03 and contribution to many-body effects in nuclei. Though there were some experimental clues and theoretical studies of this state, it was unclear whether the obtained experimental results represented a real resonance or not due to the difficulty of separation from kinematical effects. Very recently, the FOREST group at Tohoku University reported a photoproduced isovector dibaryon state at mass of 2.14 GeV?22 in the 3c0 invariant mass spectra of the W3 ! 3c0c0 reaction. The most probable ?% configuration was 2¸ although they didn?t exclude the possibility of ?% = 1¸ or 3?. They separated the dibaryon production process from conventional pion production process for the first time using angular distribution of deuteron. We investigated the W3 ! 3c¸c? reaction for study of a possible #? dibaryon state using a deuterium target at the Research Center for Electron Photon Science, Tohoku University, Japan. In the experiment, ?3 ? 1012 tagged photon beam at energies ranging from 0.8 to 1.1 GeV was impinged to the liquid deuterium target (?520 mg?cm2) and the charged particles in the final state: deuteron, c¸, and c?, were detected by a magnetic spectrometer with a large solid angle named NKS2. NKS2 had capabilities of reconstructing momentum of charged particles, multi-track analysis, and ??c separation. We performed two different analyses named 2-track analysis and 3-track analysis. The 2-track (3-track) analysis was for events in which two (three) particles of 3c¸c? in the final state, including deuteron, were detected by NKS2. In the 3-track and 2-track analysis, ?2000? ?15000 events were identified as the W3 ! 3c¸c? reaction events, respectively. The 2-track analysis with higher statistics was mainly used to derive the cross sections, and the 3-track analysis was used to check the consistency of the 2-track analysis. In this thesis, we have shown the total cross section, the differential cross sections of the W3 ! 3c¸c? reaction in the region of jC j ¡ 0?15 GeV2. This is the world?s first measurement of this reaction in this energy region. Dibaryon resonance structures were observed below the #? threshold in the differential cross section of the invariant mass of 3c?. The mass and width of the structure were consistent with these of ?12 measured by the W3 ! 3c0c0 reaction. The mechanism of the production process was discussed based on the angular distribution of emitted deuteron.

Toyama, Yuichi↗
DOE OSTI2022

Proposed Methodology for Evaluating and Validating TSLs [Slides]

This presentation begins by providing an overview of the research and discusses recent efforts in validating thermal neutron scattering cross sections, including differential cross section measurements at ORNL for evaluation and validation, total cross section measurements at RPI, pulsed-neutron die-away experiments at LLNL, and integral criticality experiments by LLNL. The presentation also proposes a methodology not only for validating thermal scattering files that utilizes all available experimental data, but also for evaluating new libraries as demonstrated on polystyrene. In conclusion, polystyrene evaluation was conducted using multiple experiments, including differential and integral. The proposed methodology has been shown to improve neutron transport and files have been submitted to NNDC for inclusion in ENDF/B-VIII.1 release. MCT-012 & PCM-002 has been relatively insensitive to changes in $\mathcal{S}(α,β)$. The research found that differences in differential results don’t always propagate to differences in integral results, hence why evaluation of differential data important. Future work on the project is also discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Photoproduction of Cascade Baryons Using the GlueX Detector at Jefferson Laboratory

Multi-strange baryons have played an important role in understanding the strong interaction. Despite their importance to advancing quantum chromodynamics (QCD), little is known about such hyperons due to the lack of a strange probe. Almost all knowledge of Cascade baryons today stems from kaon-nucleon interactions in bubble chamber experiments performed in the 1960s and 1970s. The 1980s saw advancement in electronics and computational resources allowing for higher statistic experiments such as the MultiParticle Spectrometer (MPS) at Brookhaven National Laboratory. From these previous experiments, the octet and decuplet ground states, Xi(1320) and Xi(1530) respectively, were well established with known properties and four excited states were well established. This research uses the GlueX experiment at Jefferson Laboratory to extend photoproduction cross section measurements for Xi(1320)- to higher beam energies to further understand the production mechanism, as well as to search for the first excited Cascade resonance observation in photoproduction through the decay Xi-* -> K-Lambda. The GlueX Spectrometer is a nearly hermetic detector used to study exclusive photoproduction reactions with photon beam energies up to 12 GeV. The first phase of GlueX running has recently been completed. Preliminary results for the total cross section and differential cross sections in terms of momentum transfer -t are shown within. Additionally, the first observation of an excited Cascade baryon, in particular Xi(1820)-, is shown.

Ernst, Ashley↗
NASA NTRS1989

Differential elastic electron scattering cross sections for SO2

Differential cross sections for elastic electron scattering by SO2 were measured by utilizing a modulated, crossed-beam method and calibration against He. The energy and angular ranges were from 5 to 50 eV and from 12 to 156 deg, respectively. The present results are compared with earlier data of Orient et al. (1982), and it is suggested that their cross section values should be increased by about a factor of two.

Trajmar, Sandor↗
DOE OSTI2024

State-Selective Double Photoionization of Atomic Carbon and Neon

Double photoionization (DPI) allows for a sensitive and direct probe of electron correlation, which governs the structure of all matter. For atoms, much of the work in theory and experiment that informs our fullest understanding of this process has been conducted on helium, and efforts continue to explore many-electron targets with the same level of detail to understand the angular distributions of the ejected electrons in full dimensionality. Expanding on previous results, we consider here the double photoionization of two 2p valence electrons of atomic carbon and neon and explore the possible continuum states that are connected by dipole selection rules to the coupling of the outgoing electrons in 3P, 1D, and 1S initial states of the target atoms. Carbon and neon share these possible symmetries for the coupling of their valence electrons. Results are presented for the energy-sharing single differential cross section (SDCS) and triple differential cross section (TDCS), further elucidating the impact of the initial state symmetry in determining the angular distributions that are impacted by the correlation that drives the DPI process.

Yip, Frank L. (ORCID:000000025409495X)↗
DOE OSTI2024

Interpretations of the ATLAS measurements of Higgs boson production and decay rates and differential cross-sections in pp collisions at $\sqrt{s}$ = 13 TeV

Measurements of the Higgs boson production times decay rates and differential cross-sections have recently been performed by the ATLAS experiment in several decay channels using up to 139 fb -1 of proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded at the Large Hadron Collider. This paper presents multiple interpretations of these Higgs boson measurements. Measurements of production-mode cross-sections, simplified template cross-sections and fiducial differential cross-sections in different decay channels are reparameterised in terms of the impact of Standard Model effective field theory operators, and constraints are reported on the corresponding Wilson coefficients. Production and decay rate measurements are interpreted in UV-complete extensions of the Standard Model, namely the two-Higgs-doublet model (2HDM) near the alignment limit and the Minimal Supersymmetric Standard Model (MSSM) for various MSSM benchmark scenarios. The constraints on the 2HDM parameters (cos(β - α), tanβ) and the MSSM parameters (m A , tanβ) are complementary to those obtained from direct searches for additional Higgs bosons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1976

Differential cross-section for positronium formation in electron-atomic hydrogen collisions

The L=0 and 1 partial wave amplitudes obtained by a two-state coupled static approximation with correlation with the L greater than or equal to 2 Born amplitudes were combined to obtain the differential cross section for positronium formation in electron-atomic hydrogen collisions. For positron energies of 0.64 and 0.75 ryd, minima at the scattering angles of 57 deg and 51 deg are found. Total cross sections for positronium formation for low and intermediate impact energies are given. Measurement of the differential cross section for the process positron + helium yields positronium + helium ion for the detection of possible minima is suggested.

Drachman, R. J.↗
DOE OSTI2020

Elastic differential cross-section ${\mathrm{d}}\sigma /{\mathrm{d}}t$ at $\sqrt{s}=2.76\hbox {TeV}$ and implications on the existence of a colourless C-odd three-gluon compound state

The proton-proton elastic differential cross section dσ/dt has been measured by the TOTEM experiment at √ s = 2.76 TeV energy with β* = 11 m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (|t|) from 0.36 GeV 2 to 0.74 GeV 2 . The differential cross-section can be described with an exponential in the |t|-range between 0.36 and 0.54 GeV 2 , followed by a diffractive minimum (dip) at |t dip | = (0.61 ± 0.03) GeV 2 and a subsequent maximum (bump). The ratio of the dσ/dt at the bump and at the dip is 1.7±0.2. When compared to the proton–antiproton measurement of the D0 experiment at √ s = 1.96 TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for a colourless C-odd three-gluon bound state exchange in the t-channel of the proton-proton and proton–antiproton elastic scattering.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Photoproduction of Lambda* Resonances using the CLAS Detector

This thesis presents the study of the reaction yp -> K^+Lambda* using the photo production data from the CLAS-g12 experiment performed in Hall B of Jefferson Laboratory. The decay of Lambda* resonances, Lambda(1520), Lambda(1670), and Lambda(1690), into two exclusive channels, Sigma+pi?and Sigma-pi+, is studied from the detected K+,pi+, and pi?particles. This work aims at understanding photoproduction mechanism to excited state baryons, and to facilitate phenomenological model predictions using precision experimental measurements. A good agreement is established for the Lambda(1520) differential cross sections with the previous CLAS measurements. The differential cross sections as a function of CM angle are extended to higher photon energies. Newly added are the differential cross sections as a function of invariant 4-momentum transfer, which is the natural variable to use for a theoretical model based on a Regge-exchange reaction mechanism. No new N* resonances decaying into the K+Lambda(1520) final state are found. The higher mass resonances, Lambda(1670)1/2- and Lambda(1690)3/2-, are studied for the first time using photoproduction. This work provides a model dependent preliminary cross sections for these excited states.

Shrestha, Utsav↗
DOE OSTI2024

Production of η and η ′ mesons in p p and p Pb collisions

The production of η and η ′ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.02 and 13 TeV and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16 TeV . The studies are performed in center-of-mass (c.m.) rapidity regions 2.5 < y c . m . < 3.5 (forward rapidity) and − 4.0 < y c . m . < − 3.0 (backward rapidity) defined relative to the proton beam direction. The η and η ′ production cross sections are measured differentially as a function of transverse momentum for 1.5 < p T < 10 GeV and 3 < p T < 10 GeV , respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for η and η ′ mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of η mesons are also used to calculate η / π 0 cross-section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as η and η ′ meson fragmentation. ©2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗