First order optical potentials and 25 to 40 MeV proton elastic scattering

The differential cross sections and analyzing powers from the elastic scattering of 25 and 40 MeV protons from many nuclei have been studied. Analyses have been made using a fully microscopic model of proton-nucleus scattering seeking to establish a means appropriate for use in analyses of radioactive beam scattering from hydrogen with ion energies 25A and 40A MeV.Comment: 9 pages, RevTeX, 4 figure

Proton-proton scattering above 3 GeV/c

A large set of data on proton-proton differential cross sections, analyzing powers and the double polarization parameter A_NN is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the rho, omega, f_2, and a_2 trajectories and single Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.Comment: 16 pages, 19 figures; revised version accepted for publication in EPJ

GIANT MULTIPOLE EFFECTS IN 27Al(pn) IAS

A l'aide d'une description complète de la couche S-d, nous avons analysé en ondes distordues avec antisymétrisation les sections efficaces de transition 27Al(pn) IAS entre 10 et 40 MeV. Nous y démontrons les effets d'une excitation virtuelle des résonances E1 et E2. Les contributions résonnantes y sont essentielles pour reproduire les données expérimentales en dessous de 30 MeV. La distribution du terme dipolaire concorde avec les sections efficaces totales 28Si(γn) et révèle l'existence d'une nouvelle résonance quadrupolaire dont le maximum se situe à 23 MeV d'excitation dans le 28Si. Elle se trouve donc sous la résonance dipolaire géante.Antisymmetrized DW analyses of 27Al(pn) IAS transition cross sections (10 MeV to 40 MeV) using a full s-d shell model spectroscopy, demonstrate the effects of virtual excitation of E1 and E2 resonances. Resonance contributions to this reaction are essential to fit the data below 30 MeV. The deduced dipole strength distribution agrees with the measured total (γn) cross sections from 28Si and these analyses determine a new quadrupole resonance which peaks at 23 MeV excitation in 28Si and thus lies under the giant dipole resonance