Projectile fragment emission angles in fragmentation reactions of light heavy ions in the energy region <200Â MeV/nucleon: Experimental study

Measurements of fragment emission angles for 57 and 93 MeV/nucleon 12C and 95 MeV/nucleon 16O projectiles in graphite, Plexiglas and polyethylene targets were performed using trajectory tracing technique with CR-39 detectors. The results were compared with calculations with the fragment emission angle model (FRANG). The angular resolution of the measurements was achieved to be <0.1°. The measured fragment emission angles imply that the generally accepted straight-ahead approximation of fragment emissions in nuclear collisions is oversimplified as the fragments are clearly emitted at different angles related to the primary particles. The calculated values were in agreement with the experimental ones within the margin of a few degrees for most of the examined projectile-target systems. However, some discrepancies were observed. Thus a new calculation was performed with a modified version of the model M-FRANG. For both FRANG and M-FRANG, chai-square values were calculated to test the degree of agreement with our measurements. It was confirmed that the M-FRANG showed better agreement despite its simplicity, and it was established it can be successfully used in several applications, including simple and fast test of more complicated 3D particle and heavy ion transport codes.