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The weak-field magnetic susceptibility of a thin superconducting film is calculated with a microscopic theory based on the work of Bardeen, Cooper, and Schrieffer. The finite sample size is taken into account by forming "Cooper pairs" from one-electron states whose wave functions vanish at the film boundary. Although the excitation spectrum of the superconductor remains essentially unchanged by this discrete quantization, the weak-field magnetic susceptibility is found to have a considerably lower value than previous theoretical estimates.

A method is developed for discussing the measurement of quantum mechanical observables with continuous eigenvalue spectra. In this method, the Wigner distribution function has a role similar to that of the Gibbs phase space density in the corresponding classical problem. The analysis applies to a wide class of physical situations, such as a field or a material particle. (Author)

A procedure for treating correlations in atomic structure is introduced and applied to the calculation of excitation energies, oscillator strengths, and photo-ionization cross sections. The method is the extension of the Hartree-Fock theory known as the random-phase approximation, which has already been applied to a number of other many-body problems. In this application to atomic physics, results are given for the following atoms in column II of the periodic table: beryllium, magnesium, calcium, and strontium. These atoms all have 1 sub S ground states, and only excitations to 1 sub P states are considered. The general conclusion of the study is that the values of the oscillator strengths and photo-ionization cross sections are changed significantly by the correlations, while the changes in the values of the excitation energies are quite small. Wherever comparison with experiment is possible, the inclusion of these correlations improves the agreement between theory and experiment. Their effects are, however, not as marked as in highly degenerate infinite systems or in nuclei. (Author)

Previous studies of proton-nucleus scattering have been extended to 17 Mev. As at 10 Mev, it is difficult to obtain unique sets of parameters because of the similar effects of the real part of the potential V and the interaction radius R, on the one hand, and the imaginary part of the potential W and the diffuseness parameter a, on the other. If the best half-way radius for each element is expressed as R = r/sub 0/A/sup 1/3/ x 10/sup -13/ cm, r/sub 0/ decreases from r/sub 0/ = 1.29 for light and medium elements to r/sub 0/ = 1.22 for heavy elements. Values for the diffuseness parameter near a = 0.5 x 10/sup - 13/ cm are tical model potential at this energy is -(50 + i8) Mev. Values of the reaction cross section are given. An analysis of proton-carbon scattering from 14 to 20 Mev is presented. It is also shown that proton-nucleus scattering at this energy is insensitive to the precise details of the potential in the central and surface regions. In addition the scattering is independent of the shape of the nuclear charge density for energies up to 100 Mev. (auth)

The large reaction cross sections observed for antiproton collisions with complex nuclei may be understood in terms of strong absorption in the diffuse surface of the nucleus. Large values for the real part of the potential are not required. The elastic scattering of antiprotons is also discussed.

The information which can be obtained from measurements on both the outgoing particles in single ionization is discussed for the case of high-energy electrons incident on neutral one-and two-electron atoms. The Born Approximation is used to analyze a particular experiment suggested by studies of the nuclear (p,2p) reaction. It is concluded that the momentum distribution for the single-electron orbitals of atomic systems can be determined by experiments of this type. The effects of identity and correlations are investigated, especially for the case of target helium atoms. (Author)

An analysis of recent elastic scattering experiments with 40- and 95-Mev protons is presented in terms of a velocity-independent and central complex potential. A summary of this and previous work at lower energies is given also. (auth)