This paper is aimed to improve previous results dealing with irradiation experiments of epitaxial 4H-SiC Schottky diodes in view of their application as X ray detectors. To this purpose, we have carried out a thorough comparison of results concerning the degradation of minority carriers diffusion length (L-d) induced by irradiation with 8.2 MeV electrons with the type and density of irradiation-induced traps, determined by DLTS measurements as well as with the features of the corresponding photoluminescence bands.