Obtaining radiation strength functions of some nuclei

The statistical theory of nuclear reactions is a well-developed theory describing nuclear reactions by means of statistical equilibrium based on the idea that the formation and the decay of a compound nucleus are independent processes. gamma-ray strength function is the key input for calculating the cross section of the photonuclear reactions with the statistical theory. However, the gamma-ray strength functions should be normalized using the relation between the mean resonance spacing and the average radiative capture width to give reasonable predictions of cross sections . There are no existing renormalization for A < 40 light mass range. To do such renormalization for this mass region, one needs to use a well defined nuclear level density to obtain mean resonance spacings. Therefore, the level density model that will be used in this renormalization process, should be both successful for the light mass region and for describing the collective modes, which are very important for the low-energy γ deexcitations. We use the collective semi-classical level density model including collective effects in the description of level density model parameter proposed by our research group which is the most suitable one. In summary, our recently introduced level density model including collective effects is used to renormalize the gamma-ray strength functions of light nuclei in A < 40 mass range. Obtained Gnorm coefficients are tested in (n, gamma) reactions by comparing with experimental data for the necessity of renormalization for selected light nuclei, which are Na-23, Mg-26, Al-27, P-31, Cl-35 and Cl-37.