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At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2010

From the nucleus to the quarks

Early work by A. W. Thomas and his colleagues inspired the first measurements of polarization in pion-deuteron elastic scattering. This line of research and technology developments enabled polarization experiments in electron-deuteron elastic scattering as well as the widespread use of polarized internal targets in storage rings. These ideas and techniques are now being used to study two-photon exchange effects and to make progress toward experiments that will allow for improved extractions the d/u ratio at high x.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

{phi}-meson production and the in-medium {phi}-width in proton-nucleus collisions

The production of {phi}-mesons in collisions of 2.83 GeV protons with C, Cu, Al, and Au targets has been measured with the ANKE magnetic spectrometer at the Cooler Synchrotron COSY. The {phi}-mesons were detected at small angles via their K{sup +}K{sup -} decay. The measured target mass dependence of the production cross section can be related to the in-medium {phi} width. First comparisons with model calculations suggest a significant broadening of the {phi}-width relative to its vacuum value of 4.3 MeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Studying the Atomic Nucleus - A New Era in Nuclear Structure Studies

The study of atomic nuclei is part of the fascinating quest to understand the fundamental nature and origins of matter. This field, nuclear structure, is undergoing a revolutionary transformation that is breaking cherished paradigms, opening new vistas of nuclear matter for study, and which has the promise of leading to a new comprehensive understanding. The advent of new facilities for the production and study of exotic nuclei provides access to an entirely new territory of nuclei, and advances in extreme computing are enabling similar advances in the theory of atomic nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Polarization Of The High-Energy And Of The Electron-Nucleus Bremsstrahlung In Electron-Atom Collisions

The linear polarization of bremsstrahlung radiation emitted in collisions of spin-polarized and unpolarized electrons with carbon and gold targets has been measured for an incident kinetic energy of 100 keV. We present preliminary results for the degree of linear polarization for incident unpolarized electrons as a function of bremsstrahlung photon energy.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2011

Gamow-Teller Transitions Starting from T{sub z} = +3/2 Nucleus {sup 45}Sc

Owing to its simplicity and also its nature of spin-isospin ({sigma}{tau}) excitation, Gamow-Teller (GT) transitions play key roles in the studies of nuclear structure as well as astro-nuclear processes. We studied GT transitions starting from {sup 45}Sc in a high-resolution ({sup 3}He,t) charge-exchange reactions at 0 deg. and at an intermediate incoming energy of 140 MeV/nucleon. Individual GT transitions were observed up to high excitation energy of 10 MeV and a concentration of GT strength, a resonance-like structure, was observed at 6.5 MeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Theoretical highlights on neutrino-nucleus interactions: current challenges

The present theoretical status of neutrino interactions in the few-GeV region is reviewed. Quasielastic scattering, pion production and their importance for neutrino oscillation studies are discussed, making emphasis on the open questions that arise in the comparison with new experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Superscaling predictions for NC and CC quasi-elastic neutrino-nucleus scattering

Quasielastic double differential neutrino cross sections can be obtained in a phenomenological model based on the superscaling behavior of electron scattering data. In this talk the superscaling approach (SuSA) is reviewed and its validity is tested in a relativistic shell model. Results including meson exchange currents for the kinematics of the MiniBoone experiment are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

GiBUU and Neutrino-Nucleus scattering

The Giessen BUU transport approach applied to electroweak interactions on nuclei in the few-GeV region is presented. After describing the model ingredients (elementary cross sections, medium effects and final state interactions), the impact of nuclear effects on the observables is discussed. We emphasize the interconnection of quasielastic and pion production processes, which receive a unified treatment, and its relevance for present neutrino experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Neutrino-Nucleus Coherent NC({pi}{sup 0}) Scattering in the MINOS Near Detector

Neutrino reactions recorded by the MINOS Near Detector in exposures totalling 2.8x10{sup 20} protons-on-target were searched for single, highly-forward {pi}{sup 0} mesons produced by coherent neutral current interactions {nu}{sub {mu}}+A{yields}{nu}{sub {mu}}+A+{pi}{sup 0}. Events having topologies consistent with single electromagnetic showers were isolated. Contributions from neutrino-induced backgrounds are determined using a data-driven fit of Monte Carlo distributions over sideband regions. The fit is used to project the background levels into signal regions. An excess of events above the best-fit background is observed for shower topologies of few GeV energies and at very forward angles. The partial cross section for NC({pi}{sup 0}) coherent scattering yielding E{sub vis}({pi}{sup 0})>1.0 GeV averaged over incident neutrino energies 2.4{<=}E{sub {nu}{<=}9}.0 GeV is (31.6{+-}10.5)x10{sup -40} cm{sup 2}/nucleus. Total cross sections for coherent scattering from nuclei of average nucleon number A{sub eff} = 48 and for iron (A = 56) nuclei are estimated for <E{sub {nu}>} = 4.9 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Neutrino nucleus reactions at high energies within the GiBUU model

The GiBUU model, which implements all reaction channels relevant at medium neutrino energy, is used to investigate the neutrino and antineutrino scattering on iron. Results for integrated cross sections are compared with NOMAD and MINOS data. It is shown, that final state interaction can noticeably change the spectra of the outgoing hadrons. Predictions for the Miner{nu}a experiment are made for pion spectra, averaged over NuMI neutrino and antineutrino fluxes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Analysis of charged-current neutrino-nucleus cross section

A study of the cross section for chaged-current quasielastic (CCQE) scattering on nuclei has been performed using a description of nuclear dynamics based on the Relativistic Fermi Gas model (RFG). The role played by different parametrizations for the weak nucleon form factors is analyzed taking into account the relevance of the axial mass value. The results obtained are compared with the recent data for neutrinos measured by the MiniBooNE Collaboration.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the weak charge of the carbon-12 nucleus within the P2 experiment in Mainz

The P2 experiment at the MESA facility in Mainz aims to make a high precision measurement of the weak charge of the proton, and a suitable experimental setup is currently being designed [1]. As high precision measurements of the weak charges of different particles and nuclei are differently sensitive to physics beyond the Standard Model in the form of new quantum loop correction parameters, experiments with a range of different target materials are complementary. We introduce first feasibility considerations for the determination of the Weak Mixing Angle via the scattering of electrons from carbon nuclei in a graphite target with the P2 detector setup. In order to make an estimate of the achievable precision we present analytic calculations as well as Monte-Carlo simulations. The results of Geant4 simulations of proposed experimental setups are included.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Long-range correlations in proton-nucleus collisions in MC model with string fusion

The study of long-range correlations between observables in two rapidity windows was proposed as a signature of the string fusion and percolation phenomenon. In the present work we calculate the correlation functions and coefficients for p–Pb collisions in the framework of the Monte Carlo string-parton model, based on the picture of elementary collisions of color dipoles. It describes pA and AA scattering without referring to the Glauber picture of independent nucleons collisions and includes effects of string fusion. Different types of correlations are considered: n–n, p{sub t}–n, p{sub t}–p{sub t} where n is the event multiplicity of charged particles in a given rapidity window and p{sub t} is their mean transverse momentum. The results, obtained in the present work for p–Pb collisions, are compared with available experimental results for p{sub t}–n correlations in one window and further predictions are made.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Compound nucleus decay: Comparison between saddle point and scission point barriers

One of the principal characteristics of nuclear multifragmentation is the emission of complex fragments of intermediate mass. An extension of the statistical multifragmentation model has been developed, in which the process can be interpreted as the near simultaneous limit of a series of sequential binary decays. In this extension, intermediate mass fragment emissions are described by expressions almost identical to those of light particle emission. At lower temperatures, similar expressions have been shown to furnish a good description of very light intermediate mass fragment emission but not of the emission of heavier fragments, which seems to be determined by the transition density at the saddle-point rather than at the scission point. Here, we wish to compare these different formulations of intermediate fragmment emission and analyze the extent to which they remain distinguishable at high excitation energy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Recent developments in neutrino-nucleus interactions in 1 GeV energy region

Neutrino interactions in 1 GeV energy region are discussed. A role of nucleon-nucleon correlations in understanding recent quasi-elastic cross section measurements on nuclear target is explained. An importance of a correct treatment of two-body current contribution to the neutrino inclusive cross section is addressed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Particle production with rapidity correlations in proton-nucleus collisions

We illustrate how a generalization of the JIMWLK formalism which treats independently the direct and complex conjugate amplitudes can be used to describe semi-inclusive multiparticle production with rapidity correlations in pA collisions. The evolution equations that are obtained with this formalism are susceptible of numerical implementation as a Langevin process.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗