Some observations on the first events seen at the CERN proton-antiproton collider

Track information from the central detector in UA1 experiment at the CERN proton-antiproton collider (√s = 540 GeV) is used to determine the charged particle multiplicity distribution for the pseudorapidity range vertical stroke eta vertical stroke < 1.3. The mean value for this multiplicity per unit of eta is 3.9 +- 0.3 for events having at least one track in this range. Data from the central electromagnetic and hadron calorimeters are used to examine the correlation between the transverse energy measured in the collisions and the multiplicity in the central region. (orig.)