Estimation of the freeze-out parameters reachable in a fixed-target experiment at the CERN Large Hadron Collider

Estimation of the freeze-out parameters as a function of the rapidity in Pb + Pb collisions at $\sqrt{s_{NN}}=72\mathrm{GeV}$ in the AFTER@LHC project is performed. The conventional hadron resonance gas model is used for analysis of the events generated by the UrQMD model. The results indicate that one may obtain at least a 2.5 times increase in the baryon chemical potential ${\mu }_B$ in the forward rapidity range compared to the midrapidity range. The ${\mu }_B$ values in the rapidity range of $0<y<4.5$ for AFTER@LHC are comparable to those covered by the RHIC Beam Energy Scan program. Thus, a rapidity scan in the AFTER@LHC project provides a complementary approach for study of the QCD phase diagram.

Figure 1

(a) Rapidity dependence of particle multiplicities per event generated in the UrQMD model. The particle labels are sorted according to their abundance at $y=0$. (b) The same as (a), but normalized to the corresponding value at midrapidity. The particle labels are sorted according to their abundance in the rapidity interval $2<y<2.5$.

Figure 2

(a) Rapidity scan at a fixed energy vs energy scan at a fixed rapidity. (b) ${\mu }_B$ as a function of rapidity.

Figure 3

(a) Extracted chemical freeze-out temperature and (b) ${\chi }^2$ per degree of freedom as a function of the rapidity.

Figure 4

(a) System radius parameter $R$ and (b) strangeness saturation parameter ${\gamma }_S$ as a function of the rapidity.

Figure 5

Normalized rapidity distribution produced by a single thermal source at $T=140\mathrm{MeV}$.