Experimental estimation of the charm-production cross section in pp interactions at 70 GeV/ c with the aid of the SVD setup

Charmed-particle production in pp interactions at 70 GeV/ c was studied with the SVD setup at the IHEP accelerator (Protvino). The experimental procedure used and the data-selection methods are described. Data obtained by using a quickly cycling bubble chamber and a magnetic spectrometer are analyzed. The number of inelastic-interaction events recorded in the chamber is 109000, with the charge multiplicity being n ch /4. The corresponding statistics are 4.96 event/µb. Part of the events were recorded in the magnetic spectrometer. Three three-prong decays of charged particles near the primary vertex are found on the films, two of these being recorded with the spectrometer. All three are interpreted as D − decays. Two neutral decays observed simultaneously in the chamber and in the spectrometer are interpreted as D̅^0 decays. The total cross section for cc̅ production in the Feynman variable region −1< x F <+1 is estimated at σ (cc̅) = 1.6_ - 0.7^ + 1.1 (stat.) ± 0.3(syst.)μ b . The cross-section values and the mean values 〈| x F |〉 and 〈 p ⊥〉 for D mesons are compared with other experimental results in the energy range 58–800 GeV. The data of this experiment are compatible with the cross-section estimates obtained in the beam-dump experiment at 70 GeV and with those predicted by perturbative QCD.