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[en] In a doorway model of pre-compound reactions (such as the exciton model), the fine-structure levels of Bohr's compound-nucleus model are generalized to include one or more classes of doorway states, through which flux percolates during the relaxation of the system toward equilibrium. In the 1-class-model (i.e., normal compound-nucleus model) with GAMMA >> D, Wiedenmuller and collaborators have noted the unitarity sum rule μsub(c)Tsup(c)=2ν GAMMAsub(corr)/D. We show that, in the N-class case, N sum rules of analogous form exist, one for each eigenclass. (orig.)

[en] The theory of the influence of the field of a nucleus on the nucleon fusion probability is discussed. We show that, at least for rapid fusing nucleons with the momentum k substantially larger than characteristic nuclear momenta, the main concept of the Butler--Pearson method and the resulting formula are incorrect: the effect of the field of the nucleus does not contribute to the fusion of fast nucleons into deuterons. The fusion coefficient, defined as the ratio of the fusion probability to the probability of the production of a free nucleon pair is, to the first order in 1/k, independent of the nuclear potential. In the next order, --1/k², the nuclear effect on the fusion process is slightly destructive: the deuteron yield is suppressed as the result of breakup at the front surface of the nucleus. The above result may be obtained both with use of the methods of nonrelativistic quantum mechanics and by means of the Feynman diagram technique

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[en] The extension of the statistical theory of nuclear reactions, commonly referred to as Hauser-Feshbach theory to cases where direct reactions between channels are important, is shown. The derivation can be made analytically and numerically and its domain of validity is given. The theory is applicable to the calculation of physical quantities such as energy-averaged cross sections, polarizations, analyzing powers, Ericson cross correlation functions,..

[en] The concept of random Hamiltonians is discussed in connection with the theory of nuclear spectra and nuclear reactions. Experimental evidence is presented that suggests the Gaussian orthogonal ensemble as the basis of the theory. Some theoretical results (average cross sections, the observable in detailed balance experiments) are reported and discussed

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[en] The applied nuclear projects are mainly a demonstration of the applicability of Particle Induced X-ray Emission Analysis (PIXE) to pollution studies. PIXE is found to be a convenient multi-elemental analysis which has reasonable sensitivity for most elements of interest in this area. Project 1 is a study of the rainwater quality in Pittsburgh. Comparisons to rainwater quality in rural areas and air particulate quality in Pittsburgh are included. Project 2 shows that a time period of high pollution index can be caused by excess outputs from industry or a lack of ventilation of the city. The first basic nuclear project (Project 3) is a nuclear structure study of ¹⁰⁹Cd via (d,t) reactions in order to resolve previous discrepancies. Sixteen triton groups are observed, and configurations, assigned. Systematics of states of seven Cd isotopes are constructed. Projects 4, 5 and 6 are studies of the continuum of the particle spectrum. Project 4 is a direct reaction study of ⁶⁵Cu, ¹¹⁶Cd(d,p) reactions with deuteron energies 9, 10.5 and 12 MeV. Experimental data are obtained and compared to calculations using DWBA. Projects 5 and 6 are applications of an experimental method for clean separation of compound nucleus and non-compound nucleus contributions and analysis of the former. The compound nucleus cross sections so obtained are compared to predictions by Statistical Theory including Hauser-Feshbach calculations and Weisskopf calculations with different sets of level density parameters

[en] The potential barriers and the nuclear shapes are calculated in the fragmentation theory for the various target-projectile combinations. It is shown that the choice of the reaction partners in a compound nucleus reaction can be optimized on the basis of the interaction barriers and associated nuclear shapes. The mass and charge asymmetries of the reaction are shown to be related to the interaction length, which is defined as the length of nucleus at the top of the interaction barrier. Combinations with largest mass asymmetries and interaction lengths are shown to be most favourable to the production of superheavy elements in compound nucleus reactions. The calculations are illustrated for the compound nuclei ²⁵⁸104 and ²⁶⁰106. (author)