Measurements of $\pi^-$ production in $^7$Be+$^9$Be collisions at beam momenta from 19$A$ to 150$A$GeV/$c$ in the NA61/SHINE experiment at the CERN SPS

The collaboration
Eur.Phys.J.C 80 (2020) 961, 2020.

Abstract (data abstract)
CERN-SPS. The NA61/SHINE collaboration studies at the CERN Super Proton Synchrotron (SPS) the onset of deconfinement in hadronic matter by the measurement of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra and mean multiplicities of PI- mesons produced in the 5% most central 7Be+9Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150A GeV/c obtained by the so-called h- method which does not require any particle identification. Be+Be collisions can be characterized by the energy detected in the region populated by projectile spectators. Low values of this forward energy are referred to central collision and a selection of collisions based on the forward energy is called a centrality selection. Although for Be+Be collisions the forward energy is not tightly correlated with the impact parameter of the collision, the terms central and centrality are adopted following the convention widely used in heavy-ion physics.