Study of alpha particles emitted in Fe-nucleus interactions at 1.88 GeV/n

1.88 GeV/n Fe beams of LBL were vertically irradiated to the chambers composed of a pile of plastic track detector (CR-39) and nuclear emulsion plates. The charge number of projectile fragments in Fe interactions was carefully examined by use of CR-39. The angular distributions of emitted alpha particles have been investigated for several ranges of charge numbers of projectile fragments. The result of analysis shows that the emission angle distribution of alpha particles at large angles cannot be explained by the single mechanism of the fragmentation from a clean cut spectator. For events of central collisions with smaller charges of projectile fragments, the effective temperature for the production of alpha particles turns out to be much higher than that of the evaporation theory. The results are applied to the calibration of primary energy estimation by the opening angles of alpha particles. (author)