[en] Random exchange of nucleons between interacting heavy ions is seen to play a major role in the misalignment of angular moments of the reacting partners. Incorporation of Pauli blocking is extremely important for a quantitaive explanation of the experimental data. (author)

No abstract available

[en] Parity nonconservation was studied in ²³⁹U by measuring the helicity dependence of the p-wave resonance cross section for epithermal neutrons scattered from ²³⁸U. A statistical approach was used to determine the root-mean-squared parity-violating matrix element for the mixing of p-wave and s-wave states to be M = 0.58_-0.25^+0.50 meV. This corresponds to a parity-violating spreading width of Γ^PV = 1.0. 10^-7 eV. This spreading width gives a value of 4 . 10^-7 for α_p, the ratio of strengths of the parity-nonconserving and parity-conserving effective nucleon-nucleon interactions

[en] To study the scission configuration of the nucleus system at the time of scission, some theoretical calculations based on the Brosa's random neck rupture model were carried out

[en] The combination of results obtained from complementary reactions such as particle transfer, (n,γ), and (n,e) has led to an extensive knowledge of the single particle- and vibrational structure of excited states in odd-neutron actinide nuclei. The current situation is illustrated in examples like /sup 239/U and /sup 231/Th where very complete level schemes have been obtained. Single particle-vibrational mixing has been observed in several cases including the 1/2⁺[631], 3/2⁺[631], 5/2[622], 5/2^-[752] and 7/2^-[743] configurations. For /sup 231/Th the experimental results are compared to theoretical predictions

[en] Theories of damped nuclear reactions are often expressed in terms of degrees of freedom which are familiar from simpler nuclear reactions, such as surface vibrations and nuclear transfer. However, the clean characteristics of such elementary nuclear excitations are largely washed out due to the complexity of a damped reaction where high excitations and large distortions occur. The experimental study of damped nuclear reactions is therefore, with few exceptions, limited to observables subject to overall conservation after the reaction: the mass and charge number, the momentum and energy, and the angular momentum. (Parity is also conserved but is of little use.) If the induced elementary nuclear excitations carry significant amounts of a particular observable, the distribution of this observable in the reaction complex may reach the asymptotic (long-time) limit, for which the distribution in this observable is statistical. For the angular momentum observables it is clear from experiment that the mean spin vectors do not generally reach their equilibrium values. But the statistical limit has been advocated for describing the high spin variances. Comparisons between experiment and theory are reported for angular correlations for ⁸⁶Kr reactions

[en] A method for a statistical model evaluation of fission, (n,2n) and (n,3n) cross sections from 2MeV to 20MeV neutrons on ²³⁷U, ²³⁸U, ²³⁹U and ²³⁹Pu is presented. It consists of the determination of fission width parameters by a fit to known fission cross-sections. This method makes use of neutron transmission coefficients from an adapted coupled channel model. The neutron, fission and radiative widths are calculated by the statistical model including Fermi gas model level densities. Results are given for ²³⁷U, ²³⁸U, ²³⁹U and ²³⁹Pu nuclei

[en] The empirical description of the neutron yield from the ²³³U(n,f), ²³⁵U(n,f), ²³⁹U(n,f), ²⁴⁴Cm(s.f), ²⁴⁸Cm(s.f) and ²⁵²Cf(s.f) has been performed. The parameterization used allows the peculiarities of the 'sawtooth' curve of neutron multiplicity for light and heavy fragments to be described without any free parameters.

No abstract available

[en] Measurements of absolute reaction rates for certain nonfissionable isotopes were performed, at the Institute of Nuclear Power Reactors (IRNE) Romania, using activation detector foils exposed at the centre of ΣΣ. The average microscopic integral cross sections were obtained for the following reactions: ¹⁹⁷Au(n,γ), ¹¹⁵In(n,γ), ¹¹⁵In(n,nsup(')), ²⁷Al(n,α), ⁴⁶Ti(n,p), ⁴⁷Ti(n,p), ⁴⁸Ti(n,p) and ⁵⁸Ni(n,p). The same data, the absolute reaction rates and the average microscopic integral cross sections, for the principal fissionable isotopes were obtained in the ΣΣ-ITN facility by means of absolute fission chambers. These average fission cross sections for ²³⁵U, ²³⁹Pu, ²³⁸U, ²³⁷Np, ²³²Th, ²³³U, ²⁴¹Pu were determined. (author)