14 research outputs found

    Polarization degrees of freedom in two-nucleon knockout from finite nuclei

    Get PDF
    Polarization observables for the A(e,e'NN) and A(\gamma,NN) reactions are a powerful tool to study nucleon-nucleon correlations in the nuclear medium. In this paper, model calculations for the ^{4}He(e,e'pp), ^{16}O(\vec{e},e'\vec{p}p), ^{16}O(\vec{e},e' \vec{p}n) and ^{12}C(\vec{\gamma},\vec{p}N) reactions are presented. The sensitivity of the differential cross sections and polarization observables to central and spin-dependent nucleon-nucleon correlations is discussed.Comment: 12 pages, 10 (color) figures, Talk Presented at the the Fourth Workshop on Electromagnetically Induced Two-Hadron Emission, Granada (Spain), May 26-29, 199

    Two-nucleon knockout from 4He in a translationally invariant model

    Get PDF

    Polarization observables in electronuclear two-nucleon knockout

    Get PDF
    Differential (e,e'pp) measurements are presently recognized as a way of studying short-range correlations in finite nuclei. The (e,epp\vec{e},e'\vec{p}p) and (e,epn\vec{e},e'\vec{p}n) differential cross section and polarization observables are studied in a microscopic model that accounts for the short-range correlations, outgoing-nucleon distortions, meson-exchange and Δ\Delta-isobar currents. It is pointed out that polarization observables represent an attractive alternative for absolute electronuclear two-nucleon knockout measurements. In the polarization transfer PtP'_t for (e,epp\vec{e},e'\vec{p}p), the effect of central short-range correlations is predicted to be large while at the same time the final-state interaction effects are small.Comment: 8 pages, 4 figures, to be published in Physics Letters

    Spin-dependent correlations and the semi-exclusive ^{16}O(e,e'p) reaction

    Get PDF
    The effect of central, tensor and spin-isospin nucleon-nucleon correlations upon semi-exclusive ^{16}O(e,e'p) reactions is studied for Q^2 and Bjorken x values in the range 0.2Q21.1(GeV/c)20.2 \lesssim Q^2 \lesssim 1.1 (GeV/c)^2 and 0.15 \lesssim x \lesssim 2. The fully unfactorized calculations are performed in a framework that accounts not only for the dynamical coupling of virtual photons to correlated nucleon pairs but also for meson-exchange and Δ33\Delta_{33}-isobar currents. Tensor correlations are observed to produce substantially larger amounts of semi-exclusive ^{16}O(e,e'p) strength than central correlations do and are predominantly manifest in the proton-neutron knockout channel. With the exception of the x2x \approx 2 case, in all kinematical situations studied the meson-exchange and isobar currents are a strong source of A(e,e'p) strength at deep missing energies. This feature gives the A(e,e'p) strength at deep missing energies a pronounced transverse character.Comment: 14 pages, 6 figure

    Polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei

    Get PDF
    The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The (γ,pp\gamma,pp) and (γ,pn\gamma,pn) angular cross sections, photon asymmetries and outgoing nucleon polarizations are calculated for the target nuclei 16^{16}O and 12^{12}C and photonenergies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on 3S1(T=0)^3S_1(T=0) proton-neutron and 1S0(T=1)^1S_0(T=1) proton-proton pairs in the nuclear medium. The calculations demonstrate that dominance of SS wave photoabsorption in the (γ,pn\gamma,pn) channel does not necessarily imply that the reaction mechanism is similar to what is observed in deuteron photodisintegration.Comment: 27 pages, REVTeX 3.0 with epsf.sty, 11 figures in EPS forma

    Meson and Isobar Degrees of Freedom in A(e,ep\vec{e},e'\vec{p}) reactions at 0.2Q20.8(GeV/c)20.2 \leq Q^2 \leq 0.8 (GeV/c)^2

    Full text link
    The effect of meson and isobar degrees of freedom in A(e,ep\vec{e},e'\vec{p}) and A(e,e'n) is studied for four-momentum transfers Q^2 in the range between 0.2 and 0.8 (GeV/c)^2. The calculations are performed in a non-relativistic framework with explicit (N,\Delta,\pi) degrees-of-freedom. For the whole range of momentum transfers under investigation the relative effect of the meson-exchange and isobar degrees of freedom is significant. At low missing momenta and quasi-elastic conditions, a tendency to reduce the (e,e'p) and (e,e'n) differential cross sections is noticed. The greatest sensitivity is found in the interference structure functions WLTW_{LT} and WTTW_{TT}. The recoil polarization observables, on the other hand, are moderately affected by the meson-exchange and Δ\Delta-isobar currents.Comment: 16 pages (Revtex) + 18 figures (eps file

    The O-16(e, e ' pp)C-14 reaction to discrete final states

    No full text
    corecore