Space-Time Description of Cross Sections and Durations of Neutron-Nucleus Scattering near 1 - 2 Resonances in the C- and L-Systems

The appearance of time advance (due to distortion by the non-resonant background) instead of the expected time delay in the region of a compound-nucleus resonance in the center-of-mass (C-) system is known. Here at the same conditions we study cross sections and durations of the neutron-nucleus scattering in the laboratory (L-) system. Here there are a review of papers where it is shown that such time advance is a virtual paradox and in the L-system the time-advance phenomenon does not occur and only the trivial time delay is observed. At the same time the transformations from C-system into the L-system appear to be different from the standard kinematical transformations because in the C-system the motion of a compound nucleus is absent but it is present in the L-system. Here we analyze the initial wave-packet motion (after the collision origin) and the cross section in the laboratory (L-) system. Also here (as physical revelations of profound general methodic and in very good consistent accordance with the experiment) several results of the calculated cross sections for the neutron-nucleus in comparison with the experimental data in the L-system at the range of one or two overlapped compound resonances are presented. It is shown in the space-time approach that the standard cinematic transformations of cross sections from the C-system to the L-system are not valid because it is necessary to consider the center-of- mass motion in the L-system. Finally on a correct self-consistent base of the space-time description of the nuclear processes in the laboratory system with 3 particles in the final channel, the validity of the former approach is shown, which is obtained for the space-time description of the nuclear processes with 2-particle channels earlier.