Continuum calculations of electromagnetic reactions in closed–shell nuclei

not availabl

Coincidence 16O(e,e\u2032x) cross\u2013sections and 16O(e,e\u2032x) asymmetries in the Random Phase Approximation

Predictions 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

Response functions and charge transition densities for monopole excitations in (e, e\u2032) and (e, e\u2032x) reactions of 16O and 40Ca

The 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

Momentum and density dependence of the ph interaction in continuum RPA calculations with Skyrme forces

We analyse the momentum and density dependence of the ph interaction in self-consistent RPA calculations of electromagnetic reactions with Skyrme forces. First, we calculate the V00ph and V01ph spin-isospin components in nuclear matter for an SK3 interaction. At the nuclear surface, they have decreasing values with increasing q-values up to momenta q=3 fm-1. As a second point, we show that the predictions of the 12C(e, e') charge response at 400 MeV/c remain practically unchanged when the zero-range quadratic momentum dependence of the SK3 interaction is replaced by the momentum dependence associated with a Yukawa short-ranged force

Many\u2013body effects in photoreactions of light nuclei below pion threshold

In 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

Coincidence 16O(e,e\u2032x) reactions with polarized electrons at low momentum transfer in self\u2013consistent random\u2013phase approximation theory

Coincidence (e16,ex) reactions with polarized electrons have been investigated in the one-photon-exchange formalism. Electromagnetic transition amplitudes are decomposed into multipoles. The nuclear energy continuum is obtained in the framework of a self-consistent random-phase approximation theory with a Skyrme III interaction. We focus our attention on the electron kinematics i=130 MeV, =50\ub0, and on the nuclear excitation energies =21 and 35 MeV. The polarization structure functions WLT are discussed in parallel with angular distributions and asymmetries for the two hole states: 1p1/2-1 and 1p3/2-1. At 21 MeV we explore the properties of giant multipole resonances, whereas at 35 MeV, we show theoretical predictions for the competing knockout and semidirect reaction mechanisms. The neutron yield predicted in (e16,en) reactions is connected with the presence of random-phase approximation correlations in the nuclear energy continuum. Comparison is made between random-phase-approximationSkyrme-III results and Novosibirsk experimental data

Fotoreazioni di nuclei leggeri ad energie basse ed intermedie nell’ambito di teorie a molti–corpi

non disponibil

The one\u2013nucleon energy continuum in RPA\u2013Sk3 40Ca(e, e\u2032) nuclear responses at q < 550 MeV/c

Longitudinal and transverse nuclear responses on 40Ca (e, e\u2032) electron scattering have been calculated at q 64550 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

Photoreactions of 16O in self-consistent RPA theory. III : polarized (gamma,p) and (gamma,n) angular distributions and inverse capture reactions below 60 MeV

Polarized 16O(\u3b3, p0) and 16O(\u3b3, n0) reactions below 60 MeV are analyzed in the framework of a self-consistent RPA theory with the Skyrme force Sk3. The calculations include dipole and quadrupole transitions in LWA. Asymmetries, polarizations and analyzing powers are calculated and compared with the available experimental data. Our aim is to show to what extent polarized results give additional information to that extracted from the unpolarized ones, both on the many-body structure of the nucleus and on the nature of the reaction mechanism at intermediate energies