1,721,250 research outputs found
Sezioni d’urto nucleari elettromagnetiche (e, e′) ed (e, e′x) in approssimazione di Born
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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
Derivation of free boundary equilibrium linear models by a flux perturbation method
No full textA new method to derive linear models of the axisymmetric plasma dynamic is detailed. The method follows the modified inductance approach but adopts a different set of independent variables to perturb the equilibrium. This different basis permits one to reduce the numerical computation of the model and has revealed an interesting property of the inverse inductance matrix whose elements are influenced by the plasma only if they refer to circuits facing directly the plasma column. In terms of approximations, the method proposed is equivalent to the standard modified inductance method but has the additional advantage of ensuring numerical convergence of the perturbed equilibria and therefore it allows using Picard based numerical Grad-Shafranov solvers. A linear model of the RFX-mod machine was derived with this approach and it was validated against the experiment
Fotoreazioni di nuclei leggeri ad energie basse ed intermedie nell’ambito di teorie a molti–corpi
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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
Some didactical suggestions for a deeper embedding of DC circuits into electromagnetism
Full text linkUndergraduate students often encounter great difficulties in understanding Ohm's law and electrical circuits. Considering the widespread students' beliefs and their common mistakes, as they come out from the literature and our teaching experience, we think that a relevant source of these problems comes from the fact that electrical circuits are generally treated separately from the other topics of electromagnetism, with poor reference to the circulation of the electric field. We present here a way to deal with electrical circuits that could help students to overcome their difficulties. In our approach, the electric field is the protagonist and the mathematical tool the students are asked to use is its circulation. In the light of the circulation of the electric field, the experimental Ohm's law is revisited, the concept of electromotive force is discussed and some suggestions to eliminate common misconceptions about the role of a battery in a circuit are presented
ELECTRON - A Fortan programme for the coupled-channel calculation of nu- clear electromagnetic (e,e’) form factors and cross-sections in the self-consi- stent Random Phase Approximation
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