n, 208pb , and 209Bi. All angular distributions show a pronounced diffraction pattern. For the lightest nuclei measured (6Li to 160 ) the cross section exceeds the Rutherford cross section by a factor up to 15 at angles around 45 0 • The cross section data were analysed in terms of parametrised phase shift functions using 9 free parameters and in terms of the spinless optical model using up to 7 free parameters. Good~its were obtained. A strong absorption was found for the heavy nuclei, A~124. For these nuclei, only the outermost region of the nuclear surface contributes to the scattering. A potential radius cannot be extracted regardless of the pronounced diffraction pattern. The absorption is not so strong for the medium weight nuclei, 20~A~90. Information about the nuclear surface can be extracted from the differential cross section. The weIl known phase ambiguity in the optical model was found for these nuclei. For the light nuclei (A~16) the inner region of the interaction potential contributes to the scattering. A repulsive corefor small interaction distances was able to explain the observed cross sections whicb indicates tbe nonlocal characõ f tbe true interaction.The phase shift analysis leads to good fits, but the phase shifts obtained differ significantly from those of the optical model analysis. This indicates that the phase shift analysis i8 ambiguous, too.

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gives a variety of prescriptions for deducing the spin and parity of the lowest member of a threeparticle multiplet. These prescriptions, however, fail to describe the situation we observe for 127 Sb. We show in Fig. 1 the levels of 126 Sn observed by Flynn, Beery, and Blair using the reaction 124 Sn (£,/>) 126 Sn. 7 In 127 Sb, a ^~ state can result from coupling ag" 7/2 proton to the 5" twoneutron state in 126 Sn. The principal component of the wave function for the ^" isomer could thus be stated by [Mlh ll/2 2d s/2 ) 5 -ir(\g 7/2 )] 15/2 -.It is not clear why the ^ ~ state should be the lowest member of a resulting eight-state multiplet. Possibly configuration mixing with the ^" member of a six-state multiplet formed by coupling a d 5/2 proton to the 5" state of 126 Sn could be responsible for stabilizing the ^" state with respect to the Y~ state.As a consequence of the characterization of this isomer, it is possible to suggest the presence of similar isomerism in 125 Sb, to predict an approximate 8-/isec half-life for the 5" state in 126 Sn at 2054 keV, and to point to the need for better theoretical treatment of TTV 2 states and other three-quasiparticle states.The authors wish to express thanks to the lateThe deformation for nuclei in the first half of the 2s-ld shell (A =20-28) is borne out by the well-known rotational spectra, the accurate measurements of y-ray transition probabilities and of the static quadrupole moments for the 2 + states 1 " 11 , as well as by the considerable success of Hartree-Fock and Hartree-Fock-Bogoljubov calculations. 12 " 17 Some of the theoretical results 15,18 " 20 suggest large hexadecapole in addition to quadrupole deformations. This is sup-.ported by the results of several experiments. 21 " 23 Recently, a systematic analysis of inelastic scattering of 24.5-MeV protons 24 brought definite evidence for Y 4 deformation of 20 Ne, 24 Mg, 28 Si, and 32 S. For 20 Ne, an analysis of inelastic scattering of 104-MeV a particles 25 on the basis of the Austern-Blair model lead to the same result.a particles are a good probe of the nuclear surface. The diffraction-type angular distributions of the scattered a particles assure that the scat-We have measured the cross sections for the inelastic scattering of 104-MeV a particles from 20 Ne and 28 Si. The experimental results for the ground-state band have been analyzed in terms of a coupled-channel calculation on the basis of the rotational model. This technique proves to be quite sensitive to contributions of hexadecapole deformations. Quadrupole and hexadecapole deformation lengths and their signs are determined for both nuclei.1190

Elastic and Inelastic Scattering of 104 MeV a-Particles from 5s, 60, 62, 64NiDifferential cross sections are measured for the elastic and inelastic scattering of 104 MeV ~-particles from 5s,60,62,64Ni" The experimental results are analyzed in terms of coupled channels on the basis of an anharmonic vibrational model and prove to be quite sensitive to the values of the deformation parameters. For forward angles the 4 + angular distributions of ss,6~ are dominated by a L=4 single excitation mechanism. This is in keeping with the E4-transitions observed in (e, e') scattering. From the 2i ~-and 3 +-results transition rates are derived which can be compared to results of electromagnetic methods and of inelastic proton scattering studies. The comparison indicates that the transition rates differ and are generally higher for the proton scattering. Especially in the case of the 3-states of ss,6~ the differences are obvious.The elastic cross sections are analyzed both on the basis of the usual phenomenological model and in terms of a semimicroscopic folding model resulting in values of rms-radii for the nuclear matter distribution.

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