Analyzing power fluctuations in nuclear reactions

The joint analysis of differential analyzing power (AP) and differential cross section in the nuclear reactions of +J ₁→J ₂ +J ₃ type in the region of strongly overlapping resonances are presented. Consideration is valid in the absence of the channel-channel compound nuclear correlations. The fluctuations of AP and cross section are proved to be statistically correlated, the greater the direct contribution to the reaction cross section the stronger this correlation. For the purely statistical reactions the correlation is absent. It is shown that the joint investigation of the AP and cross section fluctuations gives possibility to extract the direct reaction AP and the separate the direct and compound nucleus contributions into the reaction cross section. In particular it can be done by means of the statistical correlation (SC) analysis. Furthermore, the SC analysis may serve as a test for revealing the intermediate structure involved in the reaction. Finally, the joint study of differential AP and differential cross section may be used to determine the spins of nuclear levels and polarization of incident beam. The results are employed to separate the compound and direct contributions in the inelastic scattering of polarized protons on²⁸Si. Comparison with experiment quantitatively supports the existence of the SC between the fluctuations of AP and cross section. Possible extension of the SC analysis to the case of the presence of channel-channel compound nuclear correlations are discussed.