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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 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Measurement of {nu}-bar{sub e}-e scattering cross section with CsI(Tl) detector array and the Beyond Standard Model constraints

A search of {nu}-bar{sub e}-e scattering cross section was carried out at the Kuo-Sheng nuclear power station. Based on 29882 and 7369 kg-days of reactor ON/OFF data, respectively, at an average reactor ON {nu}-bar{sub e} flux of 6.4x10{sup 12} cm{sup -2} s{sup -1}, the standard model (SM) electroweak interaction was probed at the squared 4-momentum transfer range of Q{sup 2}{approx}3x10{sup -6} GeV{sup 2}. The ratio of experimental to SM cross section was measured [1.08{+-}0.21(stat){+-}0.16(sys)]. We placed the constraints on the electroweak parameters (g{sub V},g{sub A}), corresponding to a weak mixing angle measurement of sin{sup 2}{theta}{sub W} = 0.251{+-}0.031(stat){+-}0.024(sys). A Point Contact Germanium Detector (PCGe) of mass 1 kg has been installed at a new underground laboratory 'China Jin-Ping Laboratory (CJPL)' in China.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A new paradigm for modeling the neutrino-nucleus cross section?

There is increasing evidence that the scheme, or paradigm, successfully applied to explain the wealth of electron-nucleus scattering data fails to describe the measured quasi elastic neutrino-nucleus cross sections. I argue that, before advocating modifications of the nucleon properties in the nuclear medium, the available data should be analyzed within a new paradigm, allowing for a consistent treatment of the reaction mechanisms, other than single nucleon knockout, contributing to the flux averaged neutrino cross section.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Argon plasma modeling with detailed fine-structure cross sections

Our recently reported fully relativistic distorted-wave electron-impact cross sections from the ground and metastable states of argon to various excited fine-structure levels are incorporated in a collisional-radiative model to obtain the population densities for the 3p{sup 5}4s and 3p{sup 5}4p (1s and 2p) fine-structure manifolds for low temperature argon plasmas. Excitation cross sections from the two 3p{sup 5}4s J = 1 resonance levels, 1s{sub 2} and 1s{sub 4}, to the higher lying 2p fine-structure manifold as well as for transitions among individual levels of the 1s and 2p manifolds are also calculated and included in the present model which were not fully considered in any earlier model. Our results for the population densities of the 1s and 2p levels show good agreement with recent measurements. The variation of population densities of all the 1s and 2p levels with electron temperature and density are presented. We have also calculated and compared the intensities for the 750.38 nm (2p{sub 1}{yields} 1s{sub 2}) and 696.54 nm (2p{sub 2}{yields} 1s{sub 5}) lines with recently reported experimental results. The present work suggests that the inclusion of a complete fine-structure description of the electronic processes occurring in the plasma is important for a collisional radiative model, which includes separate 1s and 2p levels.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

New results on the pi^+pi^- electroproduction cross sections off protons

In these proceedings we present preliminary {pi}{sup {+-}} electroproduction cross sections off protons in the kinematical area of 1.4 GeV < W < 1.8 GeV{sup 2} < Q{sup 2} < 1.1 GeV{sup 2}. Our Results extend the kinematical coverage for this exclusive channel with respect to previous measurements. Furthermore, the {pi}{sup {+-}} electroproduction cross sections were obtained for Q{sup 2}-bins of much smaller size. The future analysis of this data within the framework of the JLAB-MSU reaction model (JM) will considerably improve our knowledge on the Q{sup 2} evolution of the transition {gamma}{sub 1}NN* electrocouplings, in particular for the resonances with massive 1.6 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measurement of cross sections of p(e,e'pi^+)n for near pion threshold and high-lying resonances at high Q^2

During the last decade, remarkable experimental data have been collected in an extensive programs to study the excitation of nucleon resonance (N*) at Jefferson Laboratory through pion electroproduction using polarized electron beam and unpolarized proton target. The CEBAF Large Acceptance Spectrometer (CLAS) is well suited for the study of a broad range of kinematics in the invariant mass W and photon virtuality Q{sup 2} with nearly complete angular coverage for the hadronic decays. Electron scattering allows us to probe the effective degrees of freedom in excited nucleon states from meson-baryon to dressed quarks in terms of varying the distance scale. The study of nucleon structure allows us to understand these effective degrees of freedom. In this proceeding, I present preliminary cross sections for single pion production in mass range of high-lying resonances as well as near the pion threshold. Analysis of N{pi}{sup +} cross sections together with N{pi}{sup 0} and N {pi}{pi} exclusive electroproduction data, will allow us for the first time to determine electrocouplings of several high-lying excited proton states (W {ge} 1.6 GeV) at photon virtualities that correspond to the transition toward the dominance of quark degrees of freedom. I also present preliminary result on the E{sub 0+} multipole near pion threshold at 2.0 GeV{sup 2} {le} Q{sup 2} {le} 4.5 GeV{sup 2} using exclusive N{pi}{sup +} electroproduction data.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

State-dependent photoionization cross-sections of 3d transition metal atoms

Using the saturation method, we measured the absolute photoionization cross-sections of several excited states of titanium, vanadium, chromium, iron, and cobalt. These results are reported for the first time in this paper. The measured values range from 0.4 {+-} 0.1 Mb to 6.9 {+-} 2.0 Mb. The results show that the photoionization cross-section depends on the atomic state and not just on the electronic configuration.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Empirical modeling of the cross section of damage formation in ion implanted III-V semiconductors

In this letter, the cross section of damage formation per individual ion is measured for III-V compound semiconductors ion implanted at 15 K, applying Rutherford backscattering spectrometry. An empirical model is proposed that explains the measured cross sections in terms of quantities representing the primary energies deposited in the displacement of lattice atoms and in electronic interactions. The resulting formula allows the prediction of damage formation for low temperatures and low ion fluences in these materials and can be taken as a starting point for further quantitative modeling of damage formation including secondary effects such as temperature and ion flux.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Nonlinear theory for a terahertz gyrotron with a special cross-section interaction cavity

The fully numerical nonlinear theory for a gyrotron with a special cross-section interaction cavity has been developed in this paper. In this theory, the analytical solution to different modes in the special cross-section interaction cavity is replaced by the numerical solution based on electromagnetic simulation results. A 0.4 THz third harmonic gyrotron with an azimuthally corrugated interaction cavity has been investigated by using this theory and simulation results show that this approach has a significant advantage of developing high harmonic terahertz gyrotrons.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Neutron capture cross section measurements at the beam line 04 of J-PARC/MLF

An Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) at the beam line 04 of MLF (Material and Life Sciences Experimental Facilities) of J-PARC (Japan Proton Accelerator Research Complex) was installed to measure neutron capture cross sections related to the research and development of innovative nuclear systems, the study on nuclear astrophysics, etc. ANNRI has two gamma-ray spectrometers: one is a Ge detector array placed at 22 m from the coupled type moderator of the spallation neutron source of J-PARC/MLF and the other is a pair of NaI(Tl) detectors at 28 m. Until the 11th of March, 2011, when we had big earthquakes, we measured capture cross sections of Zr-93, Tc-99, Pd-107, I-129, Cm-244, Cm-246, etc. After checking and repairing ANNRI, we restarted measurements, and ANNRI has been open to worldwide users at present.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Measurement of the keV-neutron capture cross section and capture gamma-ray spectrum of isotopes around N=82 region

The keV-neutron capture cross section and capture {gamma}-ray spectra of nuclides with a neutron magic number N= 82, {sup 139}La and {sup 142}Nd, were newly measured by the time-of-flight method. Capture {gamma}-rays were detected with an anti-Compton NaI(T1) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The results were provided with our previous measurements of other nuclides around N= 82, {sup 140}Ce, {sup 141}Pr, {sup 143}Nd and {sup 145}Nd.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Precise neutron inelastic cross section measurements

The design of a new generation of nuclear reactors requires the development of a very precise neutron cross section database. Ongoing experiments performed at dedicated facilities aim to the measurement of such cross sections with an unprecedented uncertainty of the order of 5% or even smaller. We give an overview of such a facility: the Gamma Array for Inelastic Neutron Scattering (GAINS) installed at the GELINA neutron source of IRMM, Belgium. Some of the most challenging difficulties of the experimental approach are emphasized and recent results are shown.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the inelastic proton-proton cross section with the ATLAS detector

A measurement of the inelastic proton-proton cross-section at centre-of-mass energy of Central diffraction in proton-proton collisions at {radical}(s) = 7TeV using the ATLAS detector at the Large Hadron Collider is presented. Events are selected by requiring hits in scintillator counters mounted in the forward region of the ATLAS detector and the dataset corresponding to an integrated luminosity of 20{mu}b{sup -1}. In addition, the total cross-section is studied as a function of the rapidity gap size measured with the inner detector and calorimetry.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Neutron-induced fission cross section measurements for uranium isotopes {sup 236}U and {sup 234}U at LANSCE

A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R and D). The incident neutron energy range spans from sub-thermal up to 200 MeV by combining two LANSCE facilities, the Lujan Center and the Weapons Neutron Research facility (WNR). The time-of-flight method is implemented to measure the incident neutron energy. A parallel-plate fission ionization chamber was used as a fission fragment detector. The event rate ratio between the investigated foil and a standard {sup 235}U foil is converted into a fission cross section ratio. In addition to previously measured data new measurements include {sup 236}U data which is being analyzed, and {sup 234}U data acquired in the 2011-2012 LANSCE run cycle. The new data complete the full suite of Uranium isotopes which were investigated with this experimental approach. Obtained data are presented in comparison with existing evaluations and previous data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Quantum-mechanical predictions of electron-induced ionization cross sections of DNA components

Ionization of biomolecules remains still today rarely investigated on both the experimental and the theoretical sides. In this context, the present work appears as one of the first quantum mechanical approaches providing a multi-differential description of the electron-induced ionization process of the main DNA components for impact energies ranging from the target ionization threshold up to about 10 keV. The cross section calculations are here performed within the 1st Born approximation framework in which the ejected electron is described by a Coulomb wave whereas the incident and the scattered electrons are both described by a plane wave. The biological targets of interest, namely, the DNA nucleobases and the sugar-phosphate backbone, are here described by means of the GAUSSIAN 09 system using the restricted Hartree-Fock method with geometry optimization. The theoretical predictions also obtained have shown a reasonable agreement with the experimental total ionization cross sections while huge discrepancies have been pointed out with existing theoretical models, mainly developed within a semi-classical framework.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Charge changing cross-sections for 300 A MeV Fe{sup 26+} ion beam in Al target

In the present study, total and partial charge changing cross-sections of 300 A MeV Fe{sup 26+} ion beam in Al target were measured. The CR39 nuclear track detectors were used to identify the incident charged particles and their fragments using an automated image analyzer system installed with Leica QWin Plus software. The measured value of the total charge changing cross-section is {sigma}{sub tot}= (1663 {+-} 236) mb.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Evaluation of L-shell X-ray production cross sections by impact of {sup 4}He{sup +} ions

A database of published L-subshell X-ray production cross sections due to the impact of {sup 4}He{sup +} ions on several elements is compiled. In order to evaluate the data, they are compared with theoretical calculations using the ECPSSR theory (which modifies the Plane Wave Born Approximation) and its corrections, such as Multiple Ionization of the target atom (MI), United Atom (UA), and Intra-shell coupling (IS) models. It was found that the theory does not predict reliably the experimental results for all elements and energy ranges. Furthermore, a possible universal scaling for the xray production cross sections of the L{sub {alpha}}(L{sub 3}M{sub 4}+L{sub 3}M{sub 5}) and the L{sub {gamma}}(L{sub 2}N{sub 4}+L{sub 1}N{sub 2}+L{sub 1}N{sub 3}+L{sub 1}O{sub 3}+L{sub 1}O{sub 2}+L{sub 2}N{sub 1}+L{sub 2}O{sub 4}) lines is proposed, based on reduced velocity parameters {xi}{sub L}{sup R} and {xi}{sub L1,2}{sup R}, respectively. This scaling seems to be useful for the L{sub {alpha}} experimental points and not so good for the L{sub {gamma}} line, suggesting that more extensive theoretical studies in this direction should be followed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Electron ionization of open/closed chain isocarbonic molecules relevant in plasma processing: Theoretical cross sections

In this paper, we report theoretical electron impact ionization cross sections from threshold to 2000 eV for isocarbonic open chain molecules C{sub 4}H{sub 6}, C{sub 4}H{sub 8}, C{sub 4}F{sub 6} including their isomers, and closed chain molecules c-C{sub 4}H{sub 8} and c-C{sub 4}F{sub 8}. Theoretical formalism employed presently, viz., Complex Scattering Potential-ionization contribution method has been used successfully for a variety of polyatomic molecules. The present ionization calculations are very important since results available for the studied targets are either scarce or none. Our work affords comparison of C{sub 4} containing hydrocarbon versus fluorocarbon molecules. Comparisons of the present ionization cross sections are made wherever possible, and new ionization data are also presented.

2-METHYLPROPENE↗
DOE OSTI2014

Mixed quantum/classical calculations of total and differential elastic and rotationally inelastic scattering cross sections for light and heavy reduced masses in a broad range of collision energies

The mixed quantum/classical theory (MQCT) for rotationally inelastic scattering developed recently [A. Semenov and D. Babikov, J. Chem. Phys. 139, 174108 (2013)] is benchmarked against the full quantum calculations for two molecular systems: He + H{sub 2} and Na + N{sub 2}. This allows testing new method in the cases of light and reasonably heavy reduced masses, for small and large rotational quanta, in a broad range of collision energies and rotational excitations. The resultant collision cross sections vary through ten-orders of magnitude range of values. Both inelastic and elastic channels are considered, as well as differential (over scattering angle) cross sections. In many cases results of the mixed quantum/classical method are hard to distinguish from the full quantum results. In less favorable cases (light masses, larger quanta, and small collision energies) some deviations are observed but, even in the worst cases, they are within 25% or so. The method is computationally cheap and particularly accurate at higher energies, heavier masses, and larger densities of states. At these conditions MQCT represents a useful alternative to the standard full-quantum scattering theory.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗