Angular distributions and mechanisms for light fragment formation in relativistic heavy-ion collisions

Abstract

Angular distributions are reported for 3 Ar and '~X e produced by the interaction of 8-GeV Ne and 25-GeV ' C ions with Au. A shift from a forward to a sideward peaked distribution is observed for Ar, similar to that known to occur for incident protons over the same energy interval. Analysis of these data and those for Z=S fragments indicate that reactions leading to heavy fragment emission become more peripheral as bombarding energies increase. A mechanistic analysis is presented which explores the ranges of applicability of several models and the reliability of their predictions to fragmentation reactions induced by both energetic heavy ions and protons.

Nuclear Fragmentation in Proton- and Heavy-Ion-Induced Reactions

“…Si nce pp is approximately one for Ep 2: 3 Ge V, Equation 10 doe s not predict the further de crea se in (1311) shown in Figure 9a for spa llation fra gme nts produced in re actions at highe r energies. Indications tha t the rea ction dyna mics ma y be different at hi ghe r energies are provided by the angular di stri butions for fra gments wi th masses near the boun da ry of the inte rmediate ma ss fragme nt and dee p spalla tion doma ins, shown in Figure 9b (108,109). For heavy-ion-and proton-induce d rea ctions at low energies, the angula r distributions are forward peaked in the la boratory fra me , consi ste nt wi th isotropi c em i ssi on in a frame moving wi th vel ocity ( 1311 )…”

“…(1 15) with the pa ra me terization Fi gure 9b Angular distributions fo r 37Ar fragments produced in heavy-ion-induced reac tions on 197Au and angular distributions fo r scandium isotopes produced in proton-induced reactions on 23&U (l08). Data for 37Ar are obtained from (108). The curves without data are fits based on the data of Fortney & Porile (l09).…”