Pseudorapidity distributions of charged particles produced in p-barp interactions at sqrt s =630 and 1800 GeV.

We present measurements of the pseudorapidity({eta}) distribution of charged particles ({ital dN}{sub ch}/{ital d}{eta}) produced with {vert bar}{eta}{vert bar}{le}3.5 in proton- antiprotoncollisions at {radical}{ital s} of 630 and 1800 GeV. We measure {ital dN}{sub ch}/{ital d}{eta} at {eta}=0 to be 3.18{plus minus}0.06(stat){plus minus}0.10(syst) at 630 GeV, and 3.95{plus minus}0.03(stat){plus minus}0.13(syst) at 1800 GeV. Many systematic errors in the ratio of {ital dN}{sub ch}/{ital d}{eta} at the two energies cancel, and we measure 1.26{plus minus}0.01{plus minus}0.04 for the ratio of {ital dN}{sub ch}/{ital d}{eta} at 1800 GeV to that at 630 GeV within {vert bar}{eta}{vert bar}{le}3. Comparing to lower-energy data, we observe an increase faster than ln({ital s}) in {ital dN}{sub ch}/{ital d}{eta} at {eta}=0.