Spectator response to the participant blast

Abstract

The interplay between spectator and participant matter in heavy-ion collisions is investigated in the context of a microscopic transport model. Transport simulations show that flow patterns for the participant matter are strongly influenced by the presence of the nearby spectator matter. However, the influence is mutual. During the explosion of the participant zone, the spectator matter acquires a transverse momentum P x /A that shows sensitivity to the nuclear incompressibility and to the momentum dependence of the nuclear mean field (MF). An observed change in the net average momentum per nucleon, ∆| P/A |, can be associated with the momentum dependence of the MF. For a momentum-dependent MF and a low impact parameter in a heavy system, the spectators may emerge faster than in the initial state, accelerated by the violent participant explosion. The average excitation energy and the mass of the spectators, in contrast to the momentum, show little sensitivity to the nuclear equation of state. 25.70.z, 25.75.Ld, 21.65.+f Typeset using REVT E X

Experimental study of fragmentation products in the reactions112Sn+112Snand124SnFöhr1, Bacquias2, Casarejos3 et al. 2011Phys. Rev. C202210View full textAdd to dashboardCite

“…As discussed in refs. [26,27] this leveling-off and increase in the mean velocity of the final residue with decreasing mass can be the evidence of the influence of the participant blast on the properties of the projectile-like spectator. For the lowest masses with more than 0.5 relative mass loss the data suggest that there is also a small deviation between the two systems.…”

“…Recently, high-resolution experiments on kinematical properties of projectile residues produced in midperipheral heavy-ion collisions have been proposed as a new tool to study the nonlocal properties of the nuclear force [26,27]. According to the model calculations [26], the transversal and the longitudinal momentum distributions of the spectator matter surviving the collisional stage are influenced by the participant blast, occurring after the compression phase in the colliding zone.…”

“…According to the model calculations [26], the transversal and the longitudinal momentum distributions of the spectator matter surviving the collisional stage are influenced by the participant blast, occurring after the compression phase in the colliding zone. Consequently, the momentum distributions of spectator residues in mid-peripheral collisions should be sensitive to the nuclear force.…”

Light Cluster Production at NICA

“…First and second order flow anisotropies are generated relatively early within the collisions of heavy nuclei and, thus, can serve as useful probes of the early pres- sure tensor in those collisions [30,31]. The phase transition to the quark gluon plasma is generally expected to produce a non-monotonous behavior of derivatives in the equilibrium pressure (e.g., a dip in the speed of sound c s = dp/dε) depending on the early compression and temperature [32].…”

Experimental Indications for the Response of the Spectators to the Participant Blast

“…Recently, it has been brought into the discussion [7] that the kinematical properties of the spectators in mid-peripheral collisions could carry important complementary information to the results of the above-mentioned experiments. According to these model calculations [7], the transversal and the longitudinal momentum distributions of the spectators are influenced by the participant blast, occurring after the compression phase in the colliding zone, and thus the momentum distributions are sensitive to the nuclear force. However, the momentum distributions have to be measured with high precision in order to yield conclusive results.…”