Measurements of the pseudorapidity distributions of charged hadrons produced in xenon-xenon collisions at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_\mathrm{NN}} =$ 5.44 TeV are presented. The measurements are based on data collected by the CMS experiment at the LHC. The yield of primary charged hadrons produced in xenon-xenon collisions in the pseudorapidity range $|\eta|$ $<$ 3.2 is determined using the silicon pixel detector in the CMS tracking system. For the 5% most central collisions, the charged-hadron pseudorapidity density in the midrapidity region $|\eta|$ $<$ 0.5 is found to be 1187 $\pm$ 36 (syst), with a negligible statistical uncertainty. The rapidity distribution of charged hadrons is also presented in the range $|y|$ $<$ 3.2 and is found to be independent of rapidity around $y =$ 0. Existing Monte-Carlo event generators are unable to simultaneously describe both results. Comparisons of charged-hadron multiplicities between xenon-xenon and lead-lead collisions at similar collision energies show that particle production at midrapidity is strongly dependent on the collision geometry in addition to the system size and collision energy.
Averaged and symmetrised charged-hadron pseudorapidity density distributions in XeXe collisions at $\sqrt{s_{NN}} = 5.44$ TeV, for events in the 0--80\%, 0--5\%, and 50--55\% centrality intervals. The total uncertainty is dominated by the systematic uncertainty, and statistical uncertainties are negligible.
Averaged and symmetrised charged-hadron rapidity density distributions in XeXe collisions at $\sqrt{s_{NN}} = 5.44$ TeV, for events in the 0--80\% centrality interval. The total uncertainty is dominated by the systematic uncertainty, and statistical uncertainties are negligible.
Charged-hadron pseudorapidity density in XeXe collisions at $\sqrt{s_{NN}} = 5.44$ TeV at midrapidity as a function of event centrality. The total uncertainty is dominated by the systematic uncertainty, and statistical uncertainties are negligible.
Measurements of inclusive transverse-momentum spectra for KS0 mesons produced in proton-antiproton collisions at s of 630 and 1800 GeV are presented and compared with data taken at lower energies. The ratio, as a function of pT, of the cross section for KS0 to that for charged hadrons is very similar to what is observed at lower energies. At 1800 GeV, we calculate the strangeness-suppression factor λ=0.40±0.05.
Estimated effective cross sections for events which pass the trigger and selection criteria. The uncertainties in these represent the principal source of error in the overall normalisation of the results.
Statistical errors only.
Statistical errors only.
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