1,721,151 research outputs found
COINCIDENCE - A Fortran code for the calculation of (e,e′x) differential cross-sections, nuclear structure functions and polarization asymmetry in the self-consistent Random Phase Approximation with a Skyrme interaction
No full textFotoreazioni di nuclei leggeri ad energie basse ed intermedie nell’ambito di teorie a molti–corpi
No full textnon disponibil
Photoreactions of 12C, 16O and 40Ca in self–consistent RPA theory. II. Unpolarized (γ, p) and (γ, n) angular distributions below pion threshold
No full textThe (γ, p), (γ, n) and inverse capture reactions in 12C, 16O and 40Ca below pion threshold have been analysed in the frame of a self-consistent RPA theory with a Skyrme force (Sk3). E1 and E2 transitions in LWA are present in the calculation. Thereby, EC linked by gauge invariance to the effective interaction are included in the predicted cross sections. Through an overall comparison with the available experimental data, we attain, in the present context, a good fit of data up to 80 MeV. The observed symmetric behaviour of (γ, p) and (γ, n) angular distributions is well reproduced. The rôle of nuclear correlations on the action of EC by gauge invariance is discussed
The one–nucleon energy continuum in RPA–Sk3 40Ca(e, e′) nuclear responses at q < 550 MeV/c
No full textLongitudinal and transverse nuclear responses on 40Ca (e, e′) electron scattering have been calculated at q≤550 MeV/c in self-consistent HF-SK3 and RPA-SK3 nuclear models with the full treatment of the one-nucleon energy continuum. We analyze the quenching phenomena of the charge response in terms of he RPA-SK3 nuclear dynamics. The isoscalar and isovector longitudinal currents, which fulfil the continuity equation with the Skyrme RPA hamiltonian density, are derived. The missing strength is located in the isoscalar channel
Response functions and charge transition densities for monopole excitations in (e, e′) and (e, e′x) reactions of 16O and 40Ca
No full textThe energy behaviour of the monopole (e, e') and (e, e'x) response functions of 16O and 40Ca at q = 100 MeV/c is discussed in the framework of a self-consistent RPA-SK3 theory based on the 1plh energy continuum. The microscopic structure of the resonant states is inferred from the analysis of proton and neutron monopole transition densities in the most populated decay channels. The role of the RPA final-state interactions and ground state correlations is investigated
Coincidence 16O(e,e′x) cross–sections and 16O(e,e′x) asymmetries in the Random Phase Approximation
No full textPredictions on (e,e'x) cross sections and (e,e'x) asymmetries for the nucleus 16O are given on the basis of a self-consistent RPA theory with the SK3 interaction. The discussion is focused on the analysis of the 0+ excitation mode and on the signature of isoscalar and isovector collective excitations observed in the (e,e'x) asymmetries. Comparison is made between theory and experiment for the 16O(e,e'p0) reaction
12C(e,e′p) missing momentum distributions in HF–Sk3 and RPA–Sk3 con- tinuum theories
No full textWe study the momentum distribution or reduced cross-section for electron induced 1 p3/2 proton knockout from12C in parallel kinematics. We refer to continuum self-consistent HF-Sk 3 and RPA-Sk 3 theories with a full treatment of the one-nucleon energy continuum. The PWIA limit is also shown. The12C(e, e′p0) missing momentum distribution is analyzed in connection with the energy dependence at fixed momentum transfer of the12C(e, e′) longitudinal and transverse responses. We compare our theoretical results with the available experimental data
PHOTON-A Fortran programme for the calculation of photoreaction cross-sections and polarizations in RPA theory with a Skyrme interaction
No full textMany–body effects in photoreactions of light nuclei below pion threshold
No full textIn the present paper, we discuss the reaction mechanism in photoabsorption of light nuclei below pion threshold in the frame of a self-consistent RPA theory with a Skyrme force. The role of both exchange currents in electromagnetic operators and two-body correlations in the nuclear wave function has been studied in the RPA formalism. Exchange currents in RPA calculations are related to the nucleon effective mass in the Hartree-Fock field. Comparison is made between the RPA formalism and the Gari and Hebach theory. The relative contribution of exchange currents and nuclear correlations to the photoreaction of16O is evaluated from proton threshold up to 80 MeV.E1 andE2 multipoles are included in the calculation
- …
