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The paper addresses quantitatively the question of the validity of physical predictions based on minisuperspace quantization of Einstein's theory of gravitation. It studies a homogeneous, anisotropic cosmological model of higher symmetry (the Taub model) embedded in one of lesser symmetry (the mixmaster model). The comparison of the physical behavior of these two models is based on the construction of a non-negative probability density and the associated conserved inner product which allow a consistent probabilistic interpretation of the state function of the Universe in the interesting regime of deep channel penetration. It is shown that the respective behavior is widely different. A program is set for investigating a hierarchy of models with higher symmetry embedded in models of lesser symmetry to spell out the criteria under which minisuperspace quantum results can be expected to make meaningful predictions about full quantum gravity.

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Using N=1 supergravity as the natural square root of gravity, the authors study the quantum cosmology of Bianchi type I cosmological models. This approach gives us a natural interpretation of the components of the state vector of the universe that was lacking in previous work on the square root of quantum cosmology.

We present a set of exact solutions for quantum Bianchi type-IX anisotropic cosmological models (including the Taub model) of the form Y = W e -S . These solutions are spread over all values of anisotropy near the singularity, but at larger values of the radius of the universe they are strongly peaked around the k = + 1 Friedmann-Robertson-Walker model.

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New experiments on crystal assisted collimation have been carried out at the CERN SPS with stored beams of 120 GeV/c protons and Pb ions. Bent silicon crystals of 2 mm long with about 170 μrad bend angle and a small residual torsion were used as primary collimators. In channeling conditions, the beam loss rate induced by inelastic interactions of particles with the crystal nuclei is minimal. The loss reduction was about 6 for protons and about 3 for Pb ions. Lower reduction value for Pb ions can be explained by their considerably larger ionization losses in the crystal. In one of the crystals, the measured fraction of the Pb ion beam halo deflected in channeling conditions was 74%, a value very close to that for protons. The intensity of the off-momentum halo leaking out from the collimation station was measured in the first high dispersion area downstream. The particle population in the shadow of the secondary collimator–absorber was considerably smaller in channeling conditions than for amorphous orientations of the crystal. The corresponding reduction was in the range of 2–5 for both protons and Pb ions