Dynamical evolution of spectator systems produced in ultrarelativistic heavy-ion collisions

Abstract

In peripheral heavy-ion collisions at ultra-relativistic energies, usually only parts of the colliding nuclei effectively interact with each other. In the overlapping zone, a fireball or quark-gluon plasma is produced. The excitation energy of the heavy remnant can range from a few tens to several hundreds of MeV, depending on the impact parameter. The decay of these excited spectators is investigated in this work for the first time within a dynamical approach based on the multidimensional stochastic Langevin equation. The potential of this exploratory work to understand the connection between electromagnetic fields generated by the heavy spectators and measured pion distributions is discussed.

Role of the Spectator System in Electromagnetic Effects

“…The corresponding calculation was performed with the 4DLangevin code, where the initial conditions were taken from ABRABLA, similarly as in Ref. [9]. Our 4DLangevin prediction shows that nucleons are mostly evaporated in a time below 600 fm/c in the spectator c.m.s.…”

“…In Ref. [9] the predictions for excitation energies were presented within different theoretical approaches. For instance, the geometrical (macroscopic) approach was based on the assumption that the remnant of the collision of two nuclei at ultrarelativistic energies has a shape of a sphere cut by a cylinder.…”

“…In Ref. [9] we discussed the fission life time, but the latter fission constitutes only a small part of the hot spectator de-excitation in Fig. 3.…”

“…Its application to ultrarelativistic energies, that is, to P b+P b reactions at 158 GeV/nucleon considered here, was presented in Ref. [9].…”

Spectator induced electromagnetic effects in heavy-ion collisions and space-time-momentum conditions for pion emission

“…[1]). However, the spectators are rather highly excited systems [27]. Therefore, presently we impose a scenario with expansion of the spectators.…”