R.H. Bassel

Ambiguities in the optical potential for strongly absorbed projectiles

The origin of the discrete ambiguities that exist in the parameters of the optical model for 10 to 30 Mev deuteron scattering is explained, and it is pointed out that these ambiguities persist for other energies and other strongly absorbed projectiles such as He 3, He 4, and heavier ions. Optical model predictions for the scattering of 11.8-Mev deuterons from Zr and 43-Mev alpha particles from Ni58 are used as an illustration of the ambiguities.

EXCITATION OF NUCLEAR OCTUPOLES BY PROTON SCATTERING

The analysis of proton scattering in terms of direct interaction theory is a powerful tool for the study of a 3octupole-vibration state in nuclei through both experimental and theoretical predictions. Because angular distribution is sensitive not only to the multiple order of the transition but also to the radial distribution of the interaction in elastic scattering above the Coulomb barrier, greater detail can be used in testing the predictions of various nuclear models. (R.E.U.)

Elastic and inelastic scattering of heavy ions

Abstract The elastic and inelastic scattering of heavy ions from nuclei are considered in terms of a generalized optical model. Amplitudes for the single excitation of target or projectile are evaluated in distorted waves approximation, while amplitudes for more complicated excitations, such as double excitation or mutual excitation of both nuclei, are computed using the derivative relations of Austern and Blair. For the special case of double excitation the results of the Austern and Blair theory are compared with the predictions of a coupled Schrodinger equations calculation. Spectroscopic information derived from these analyses is in good agreement with previous analyses.

Alpha-gamma angular correlations and the distorted-waves theory☆

The angular correlation between the alpha particle inelastically- scattered from the 4.43-Mev level of C/sup 12/ and its de-excitation gamma ray was measured at various scattering angles to test theoretical predictions of the correlation parameters. Data are presented in graphical form. (L.N.N.)

Energy dependence of the elastic scattering and polarization of protons on 40Ca

Abstract Absolute differential cross sections and polarizations for elastic proton scattering from 40 Ca were measured at incident proton energies of 35.8 and 45.5 MeV. These data, together with similar data at 30.0 and 40.0 MeV, were analysed with a fixed geometry optical potential to obtain an energy dependence of the real-central well for 40 Ca of d V 0 /d E = −0.32. Unsatisfactory optical-model fits to the large angle data are shown to be easily improved by a slight adjustment of the reflection coefficients associated with the nuclear associated with the nuclear surface. Calculated phase shifts give no indication of elastic scattering resonances in the energy range 30.0 ≦ E p ≦ 45.5 MeV.

Scattering from oriented deformed nuclei

The elastic scattering of particles from oriented, deformed, odd-mass nuclei is studied, using the collective model of the nucleus. Numerical results, obtained using the distorted-wave Born-approximation, are presented for some typical cases, namely neutrons of 2, 5, and 14 Mev, protons of 5 and 14 Mev, and alphas of 43 Mev, incident on Mn/sup 56/ and Ho/sup 165/ target nuclei. It is found that the differential cross-section shows large azimuthal asymmetries when the target is oriented perpendicular to the incident beam. The experimental observation of this effect would be valuable; for rotational nuclei it could measure the sign and magnitude of the deformation, while for vibrational nuclei it could yield important information about the coupling of the odd nucleon to the core. (auth)

Distorted-waves analysis of quasi-elastic (p, n) and (He3, t) reactions

Experimental evidence has shown that the (p,n) and (He/sup 3/,t) reactions on medium-weight nuclei excite relatively strongly a state in the residual nucleus that is the isobaric analog of the target ground-state. A distorted-wave Born approximation analysis was made for V/sup 51/(p,n) at 12.1 Mev and Fe/sup 56/(He/sup 3/,t) at 25 Mev. The resulting cross sections for transitions to excited states show this method to be a very good approximation and to have the advantage that Coulomb effects can be included easily; so the theory can be applied at relatively low energies. (H.D.R.)