Evidence of a rise in the antiproton-proton total cross section at the CERN intersecting storage rings

We measured the total cross section for $\text{p}$p scattering at $\text{s}\text{= 52.8}\text{GeV}$ at the CERN ISR, using the direct, total-rate method. The result obtained, $\text{σ}{}_{\mathrm{<mtext>tot</mtext>}}\text{(}\text{p}\text{p}\text{) = 44.70 ± 0.53}\text{mb}$, shows that, in common with σ_tot(pp), this cross section also starts to rise in the ISR energy range. We remeasured the total cross section for pp scattering at the same energy, obtaining σ_tot(pp) = 43.26 ± 0.33 mb, and found for the difference, $\text{Δσ}{}_{\mathrm{<mtext>tot</mtext>}}\text{= σ}{}_{\mathrm{<mtext>tot</mtext>}}\text{(}\text{p}\text{p}\text{) ? σ}{}_{\mathrm{<mtext>tot</mtext>}}\text{(}\text{pp}\text{)}$, a value of 1.44±0.45 mb.