Search results for "Nucleon"
showing 10 items of 1041 documents
Mass distributions of the system136Xe+208Pb at laboratory energies around the Coulomb barrier: A candidate reaction for the production of neutron-ric…
2012
Reaction products from the system ${}^{136}\mathrm{Xe}+{}^{208}$Pb at ${}^{136}$Xe ions laboratory energies of 700, 870, and 1020 MeV were studied by two-body kinematics and by a catcher-foil activity analysis to explore the theoretically proposed suitability of such reaction as a means to produce neutron-rich nuclei in the neutron shell closure $N=126$. Cross sections for products heavier than ${}^{208}$Pb were measured and were found sensibly larger than new theoretical predictions. Transfers of up to 16 nucleons from Xe to Pb were observed.
Coulomb breakup of 23O
2005
Abstract The ground-state structure of the near-drip-line nucleus 23O has been investigated in a one-neutron Coulomb breakup reaction. Differential cross sections d σ / d E * for electromagnetic excitation of 23O projectiles (422 MeV/nucleon) incident on a lead target have been obtained from the measurement of the momenta of all breakup products including γ rays. The analysis of the deduced dipole-transition probability into the continuum infers a 2 s 1 / 2 ⊗ O 22 ( 0 + ) ground state configuration with a spectroscopic factor of 0.77(10) and thus a ground-state spin I π ( O 23 ) = 1 / 2 + , resolving earlier conflicting experimental findings. Final-state interaction is of significant influe…
An extended Lipkin-type model with residual proton-neutron interaction
1997
Abstract The Lipkin-Meshkov-Glick (LMG) model is extended to explicitly take into account the proton and neutron degrees of freedom. The proton and neutron Hamiltonians are taken to be of the LMG form, and, in addition, a residual proton-neutron interaction is include. Exact solutions in an SU (2) ⊗ SU (2) basis as well as the RPA solutions for the energy spectrum of the model Hamiltonian are obtained. The spectrum of the exact solutions is degenerate in the limit of no proton-neutron residual interaction, but this degeneracy is totally removed when this type of residual interaction is turned on. The spectrum obtained with RPA is compressed or expanded, as compared to the LMG model with the…
The role of the neutron electric form factor ind(e, e? N)N including polarization observables
1988
The influence of the neutron electric form factor on various observables in two-body break-up of deuterons by electrons such as differential cross section, beam, target and beam-target asymmetries and outgoing nucleon polarization as well is investigated for different kinematic regions. The electron-deuteron vector asymmetryAedV and the outgoing nucleon polarization component P′x(n) are the most promising observables in and off the quasi-free region for a determination ofGEn. Also the single polarization observablesAdT and Py0(p) and the double polarization observable P′z(n) show significant influences fromGEn.
Nucleon electromagnetic form factors in the timelike region
2012
The electromagnetic form factors of the proton and the neutron in the timelike region are reviewed. In view of the forthcoming experimental projects devoted to investigate these observables, we present the current status of the field and we emphasize the relevant role, that accurate measurements, refined phenomenological analyses, as well as microscopic models will play with the goal of achieving deeper insights into the structure of the nucleon and its inner dynamics.
The imaginary part of the nucleon self-energy in hot nuclear matter
1996
A semiphenomenological approach to the nucleon self-energy in nuclear matter at finite temperatures is followed. It combines elements of Thermo Field Dynamics for the treatment of finite temperature with a model for the self-energy, which evaluates the second order diagrams taking the needed dynamics of the NN interaction from experiment. The approach proved to be accurate at zero temperature to reproduce Im(Sigma) and other properties of nucleons in matter. In the present case we apply it to determine Im(Sigma) at finite temperatures. An effective NN cross section is deduced which can be easily used in analyses of heavy ion reactions.
Spectra and ratios of identified particles in Au+Au andd+Au collisions atsNN=200GeV
2013
The transverse momentum (p(T)) spectra and ratios of identified charged hadrons (pi(+/-), K-+/-, p, (p) over bar) produced in root s(NN) = 200 GeV Au + Au and d + Au collisions are reported in five different centrality classes for each collision species. The measurements of pions and protons are reported up to p(T) = 6 GeV/c (5 GeV/c), and the measurements of kaons are reported up to p(T) = 4 GeV/c (3.5 GeV/c) in Au + Au (d + Au) collisions. In the intermediate p(T) region, between 2 and 5 GeV/c, a significant enhancement of baryon-to-meson ratios compared to those measured in p + p collisions is observed. This enhancement is present in both Au + Au and d + Au collisions and increases as th…
Dispersion relations and the spin polarizabilities of the nucleon
1997
A forward dispersion calculation is implemented for the spin polarizabilities $\gamma_1, ... ,\gamma_4$ of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at ${\cal O}(\omega^3)$. In the absence of a direct experimental measurement of these quantities, a dispersion calculation serves the purpose of constraining the model building, and of comparing with recent calculations in heavy baryon chiral perturbation theory.
Charged current weak production of the Delta resonance
1999
The charge changing weak production of Delta in nucleons and nuclei is studied. The reactions e^{-} p -> Delta^{0} ��_{e} and e^{+} p -> Delta^{++} \bar��_{e} are considered as a possible source of information about the weak N-Delta transition form factors. The low q^2 BNL data on neutrino production of Delta are used to extract the axial vector N-Delta coupling, taking into account the deuteron structure and the Delta width. Finally, pion production induced by neutrinos in ^{16}O in the Delta region, relevant to atmospheric neutrino experiments, is investigated.
Coulomb breakup of psd-shell neutron-rich nuclei
2005
Inelastic scattering of loosely bound nuclei by Coulomb interaction at intermediate energies (400?600 MeV/nucleon) has been utilized as a spectroscopic tool for exotic nuclei. The observed electromagnetic dipole (E1) strength above the one neutron threshold of neutron-rich C, Be, B and O isotopes can be explained by a non-resonant transition of a neutron into the continuum. The shape of these strength distributions reflects properties of the wavefunction of the released neutron in the nucleus and hence ground-state properties of these isotopes. Neutron capture cross-sections such as for the 14C(n,?) 15C reaction which are of astrophysical relevance can be deduced indirectly.