Projectilelike fragment emission angles in fragmentation reactions of light heavy ionsin the energy region 200MeV∕nucleon: Modeling and simulations

Abstract

A new semiempirical model called FRANG for calculation of fragment emission angles in light and heavy ion fragmentation reactions was developed. Contributions from both central and peripheral collisions were investigated, where fragmentation occurs due to nuclear and Coulomb interaction, respectively. For central collisions the reaction was described by a two step abrasion-ablation model, where collision parameters were determined from a simple geometrical model. The fragment emission angles were calculated using a parametrization of longitudinal momentum loss and transverse momentum uptake in the collision of projectile and target atom. For peripheral collisions the Coulomb excitation of nucleon vibration resonances and subsequent decay into fragments was taken into account. Fragment emission angles were calculated from deflection in the electric field and from the amplitude of vibrations in excited nuclear states. The modeled emission angles were in accordance with the experimental values for most projectile-target systems examined and compared. It was established that the model very well reproduces the experimental results in the energy region Ͻ200 MeV/ nucleon, despite its simplicity, and can be successfully employed in several applications. The model is estimated to be valid in the energy range from a few 10 MeV/ nucleon up to few 100 MeV/ nucleon.

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

“…The usage of the trajectory tracing method, makes it possible to measure fragment emission angular distributions and to analyze the kinematics of heavy ion reactions (Giacomelli et al, 2004). For each pair of detectors, before and after the target, sets of tracks (multiplets) belonging to the initial projectile and the reaction product trajectories were fitted to straight lines, from which the directional vectors were determined.…”

“…Simulations were performed with the FRANG model (Giacomelli et al, 2004) and compared to the measured emission angles. The emission angle distributions of the fragments with given mass (A F ) and charge (Z F ) produced by a specific projectile were first calculated for probable A F eZ F combinations, and then they were averaged over the isotopes to obtain the average emission angle distribution of the fragment with Z F .…”

“…In ref. (Giacomelli et al, 2004), an approximation with an empirical parameterizations was used. To summarize briefly, the longitudinal momentum after the collision can be written as P jj;after ¼ ð1 À y 0 f ðbÞÞP jj;before ;…”

“…Therefore, we developed a semi-empirical model called FRANG (the fragment emission angles model) to predict the fragment emission angular distributions for projectile fragments produced in collisions of light projectile with a target atoms (Giacomelli et al, 2004). In the present work, the main aim is the verification of the FRANG model, but we also present new experimental results for 12 C and 16 O projectiles (Giacomelli et al, 2004) together with the calculated fragment emission angles, as well as a modified and improved version of FRANG called M-FRANG.…”

Dispersion of longitudinal momentum distributions induced in fragmentation reactions

“…One can find an expression of the mass dependence of the Fermi momentum in reference [67] that relies on data from [68]:…”