Multipole moments ofSm154andEr

Abstract

Inelastic scattering of 134 MeV polarized protons from ' Sm and ' Er has yielded angular distributions of both cross sections and asymmetries for J =0+ to 6+ members of the ground state rotational bands. Deformation parameters P"Pq, and P6 have been extracted from an analysis using coupled channels calculations for scattering from a deformed optical potential. The angular distributions of the cross sections have also been compared with an analytic eikonal model of the reaction. Multipole moments of the potential are determined and are compared with similar moments obtained from electromagnetic measurements and other hadron scattering experiments at different energies. A small energy dependence of the moments for '"Sm is observed. Comparisons are also made to moments obtained from Hartree-Fock calculations and from a liquid drop model. The observed hexadecapole moment of '"Sm is consistently higher than the theoretical predictions. NUCLEAR REACTIONS ' Sm(p, p'), ' Er(p, p'), E =134 MeV, polarized beam; enriched targets, magnetic spectrograph (45 keV FWHM): measured o. (Ep, O), A~(Ep, O); coupled channels calculations, deduced optical model parameters; comparisons with electromagnetic measurements, (p, p') and (a, a'), Hartree-Fock and liquid drop calculations.

Nuclear Shapes in Mean Field Theory

“…It is well known, fo r instance, that fo r well-deformed systems fJ 2 is always positive, and fJ 4 changes sign once near mid shelL Consequently, one expects fJ6 to change sign twice within a major shell. Initial microscopic calculations of equilibrium fJ 6 deformations by Nilsson et al (472) reproduced this trend qualitatively, and the recent experimental data for deformed Th and U nuclei give some evidence fo r a sign change near A = 240 (470).…”

“…Both experimentally and theoretically, very little is known about the sur face multipole moments of order higher than fo ur. For A = 6 (hexaconta tetrapole), some evidence exists based on (ct, ct ' ) (465-467) and (p, p') (468)(469)(470) experiments. From the simple shell model arguments it fo llows that the total intrinsic moment of even multipolarity A should change sign [(.1/2) -1] times within a major shell (47 1).…”