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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Phenomenology of nonperturbative charm in the nucleon

We perform a comprehensive analysis of the role of nonperturbative (or intrinsic) charm in the nucleon, generated through Fock state expansions of the nucleon wave function involving five-quark virtual states represented by charmed mesons and baryons. We consider contributions from a variety of charmed meson-baryon states and find surprisingly dominant effects from the D¯ *0 Λ c + configuration. We pay particular attention to the existence and persistence of high-x structure for intrinsic charm, and the x dependence of the c-c¯ asymmetry predicted in meson-baryon models. We discuss how studies of charmed baryons and mesons in hadronic reactions can be used to constrain models, and outline future measurements that could further illuminate the intrinsic charm component of the nucleon.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Scattering processes and resonances from lattice QCD

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lighter hadrons, so a complete approach to QCD is required. Presently, lattice QCD is the only available tool that provides the required nonperturbative evaluation of hadron observables. This paper reviews progress in the study of few-hadron reactions in which resonances and bound states appear using lattice QCD techniques. The leading approach is described that takes advantage of the periodic finite spatial volume used in lattice QCD calculations to extract scattering amplitudes from the discrete spectrum of QCD eigenstates in a box. An explanation is given of how from explicit lattice QCD calculations one can rigorously garner information about a variety of resonance properties, including their masses, widths, decay couplings, and form factors. Finally, the challenges which currently limit the field are discussed along with the steps being taken to resolve them.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Present and future of JLab CLAS12 physics program

The CLAS12 detector at Jefferson Lab produced the first results in SIDIS and DI-HADRON reactions. Making use of the CEBAF high energy (up to 11 GeV) and highly longitudinal polartized (up to 90%) electron beam will cover unexplored territories in electron-scattering physics. Exclusive reactions on nuclons and nuclei will be measured with high precision in high luminosity (up to 10e35 cm-2s-1) experiments. Mapping out a new class of structure functions, GPDs and TMDs, detecting and reconstructing exotic meson and baryon states and accessing nucleons correlations in nuclei, in the next decade, the CLAS12 rich physics program will provide insight in the complex dynamics of the QCD paving the road to the EIC physics. In this talk, the CLAS12 detector and JLab Hall-B physics program will be described reporting some preliminary results for flag-ship reactions and plans for future upgrades of the detector.

Battaglieri, Marco↗
DOE OSTI2011

Nuclear Shell Structure in Semi-Realistic Mean-Field Approach

By applying the Hartree-Fock calculations with the newly developed methods and interactions, spherical shell structure of medium-mass nuclei is investigated, with paying special attention to the magicity.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

EUROv Super Beam Studies

Neutrino Super Beams use conventional techniques to significantly increase the neutrino beam intensity compared to the present neutrino facilities. An essential part of these facilities is an intense proton driver producing a beam power higher than a MW. The protons hit a target able to accept the high proton beam intensity. The produced charged particles are focused by a system of magnetic horns towards the experiment detectors. The main challenge of these projects is to deal with the high beam intensity for many years. New high power neutrino facilities could be build at CERN profiting from an eventual construction of a high power proton driver. The European FP7 Design Study EUROv, among other neutrino beams, studies this Super Beam possibility. This paper will give the latest developments in this direction.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

T2K: ND280 Status, Progress, and Plans

T2K(Tokai to Kamioka) is an off-axis long baseline (295 km) neutrino oscillation experiment designed to search for v{sub {mu}} {yields} v{sub e} appearance. The neutrino beam is generated using 30 GeV protons from the J-PARC facility at Tokai, Japan. The Near Detector(ND280) is located in J-PARC and the Far Detector, Super-Kamiokande, in Kamioka, Japan. Presented is a summary of the status and plans of the Near Detector suite.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

THE {gamma}SF METHOD

The {gamma}-ray strength function ({gamma}SF) interconnects radiative neutron capture and photoneutron emission as a common ingredient in the statistical model. Outlined here is an indirect method of determining radiative neutron-capture cross sections for unstable nuclei based on the {gamma}-ray strength function. Application examples of the {gamma}SF method are demonstrated.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions

Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A{approx}200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n,xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Spectroscopic study of {Lambda}(1405) via the in-flight (K{sup -},n) reaction on deuteron

We present an experimental study of {Lambda}(1405) via the in-flight (K{sup -},n) reaction on the deuteron target (J-PARC E31). We will measure all {Sigma}{sup +}{pi}{sup -}, {Sigma}{sup -}{pi}{sup +} and {Sigma}{sup 0}{pi}{sup 0} final states so that the isospin structure of the produced hyperon resonance state can be decomposed. In this report, we present an overview of the experiment and preparation status.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Deep Inelastic Electron Scattering Off the Helium and Tritium Mirror Nuclei

We discuss a possible measurement of the ratio of nucleon structure functions, F{sub 2}{sup n}/F{sub 2}{sup p}, and the ratio of up to down quark distributions, u/d, at large Bjorken x, by performing deep inelastic electron scattering from the {sup 3}H and {sup 3}He mirror nuclei with the 11 GeV upgraded beam of Jefferson Lab. The measurement is expected to be almost free of nuclear effects, which introduce a significant uncertainty in the extraction of these two ratios from deep inelastic scattering off the proton and deuteron. The results are expected to test perturbative and non-perturbative mechanisms of spin-flavor symmetry breaking in the nucleon, and constrain the structure function parametrizations needed for the interpretation of high energy collider and neutrino oscillations data. The precision of the expected data can also test models of the nuclear EMC effect and provide valuable input for its full explanation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Isotopic yield measurement in the heavy mass region for {sup 239}Pu thermal neutron induced fission

Despite the huge number of fission yield data available in the different evaluated nuclear data libraries, such as JEFF-3.1.1, ENDF/B-VII.0, and JENDL-4.0, more accurate data are still needed both for nuclear energy applications and for our understanding of the fission process itself. It is within the framework of this that measurements on the recoil mass spectrometer Lohengrin (at the Institut Laue-Langevin, Grenoble, France) was undertaken, to determine isotopic yields for the heavy fission products from the {sup 239}Pu(n{sub th},f) reaction. In order to do this, a new experimental method based on {gamma}-ray spectrometry was developed and validated by comparing our results with those performed in the light mass region with completely different setups. Hence, about 65 fission product yields were measured with an uncertainty that has been reduced on average by a factor of 2 compared to that previously available in the nuclear data libraries. In addition, for some fission products, a strongly deformed ionic charge distribution compared to a normal Gaussian shape was found, which was interpreted as being caused by the presence of a nanosecond isomeric state. Finally, a nuclear charge polarization has been observed in agreement, with the one described on other close fissioning systems.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Further evidence for the broad 2{sub 2}{sup +} state at 9.6 MeV in {sup 12}C

We measured the {sup 12}C(p,p{sup '}){sup 12}C* reaction at 25 MeV at the three laboratory angles of 20 deg., 35 deg., and 45 deg. The measured spectra support recent evidence for a new broad2{sub 2}{sup +} state at 9.6 MeV in {sup 12}C, but do not support the claim for such a broad state at 11.1 MeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Proton-capture Nucleosynthesis In Low Mass Stars: Effects of New Reaction Rates

We present computations of nucleosynthesis in low-mass asymptotic-giant-branch stars of solar metallicity experiencing deep mixing. In this framework, we discuss the effects of recent improvements in relevant reaction rates for proton captures on intermediate-mass nuclei. The calculations are then performed on the basis of a parameterized circulation, where the effects of the new nuclear inputs are best compared to previous works. We find that especially the new reaction rate for the {sup 14}N(p,{gamma}){sup 15}O reaction implies considerable modifications in the composition of low mass red giant stars.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Experiments for the astrophysical p process with the in-beam method

We performed a proton-capture reaction on {sup 92}Mo at energies relevant for the p process. The reaction was investigated by the in-beam technique using the {gamma}-ray detector array HORUS (High efficient Observatory for {gamma}-Ray Unique Sectroscopy) at the TANDEM ion accelerator of the University of Cologne.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Overview of coupled-channels analyses of meson production reactions: The way to the N*s

We provide a brief review of the main existing theoretical efforts to extract and interpret the properties of baryon resonances from the experimental data for hadro-, photo- and electro-production of mesons on the nucleon. The focus is set on the dynamical coupled-channels models. An effort is made to highlight the relevant aspects of the different approaches, within the space limitations of these proceedings.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Pion Production for Neutrino Factory-challenges

One of the key issues in the design of a Neutrino Factory target station is the determination of the optimum kinetic energy of the proton beam due to the large uncertainties in simulations of protons impinging on nuclear targets. In this paper we have developed a procedure to correct GEANT4 simulations for the HARP data, and we have determined the yield of muons expected at the front-end of a Neutrino Factory as a function of target material (Be, C, Al, Ta and Pb) and energy (3-12 GeV).The maximum muon yield is found between 5 and 8 GeV for high Z targets and 3 GeV for low Z targets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗