First results on complete events from pp collisions at the cm energy of 540 GeV.

First results from the UA5 detector on charged particle production at √s = 540 GeV in the pseudorapidity range {divides}ν{divides} < 5 are presented. The central region pseudorapidity density is 3.0 ± 0.1 for non-diffractive events. The central width of the observed ν-distribution is narrower than expected from a simple extrapolation of ISR data,suggesting an increase in the mean pt for hadron production. © 1981.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Forward-backward multiplicity correlation in pbar - p collisions at √s = 540 GeV

Results on correlations in charged multiplicity are presented using data from the UA5 detector at the CERN SPS collider. Both short-range and long-range correlations are observed. Our analysis gives no evidence for intrinsic long-range correlations. The observations are consistent with a physical picture in which small clusters are emitted at random along the rapidity axis in the plateau region. This result may indicate that random soft processes play a dominant role in high energy hadronic collisions. The average cluster size is about 2 charged particles, the same as at ISR energies. No variation of cluster size with multiplicity has been observed. The forward-backward long-range correlation and its energy dependence are related to the ratio of the first two moments, variance/mean, of the multiplicity distributions. © 1983.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Particle multiplicities in pbar p interactions at √s=540 GeV

We present the charged multiplicity distribution in pp interactions at √s=540 GeV. Moments of the distribution are given, and compared with KNO scaling predictions. An estimate of the particle composition at collider energies is also made. © 1983.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The UA5 high energy pp simulation program

The UA5 Monte Carlo program, consisting of a non-diffractive event generator GENCL, a diffractive event generator DIFFR and a tracking program are described. The inputs to the event generators are explained in detail. Their outputs are compared to available data from the SppS Collider, and the agreement is shown to be good. The importance of some features of the generators are discussed. It is shown that cluster production and leading baryons are necessary to describe non-diffractive phenomena. © 1987.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Photon production at c.m. energies of 200 and 900 GeV

We present data on photon production in non single-diffractive p {Mathematical expression}-collisions at c.m. energies of 200 and 900 GeV. Besides the general properties of photon production, i.e. pseudorapidity distribution and average multiplicity, we also investigate photon-charged two-particle pseudorapidity and multiplicity correlations. We find for the average number of photons in non single-diffractive p {Mathematical expression}-collisions 22.2±1.4±2.0 at 200 GeV and 41.4±2.1±3.5 at 900 GeV, where the first error is statistical and the second systematic. The analysis of photon-charged particle multiplicity correlations reveals strong positive correlations between the average number of photons and the number of simultaneously produced charged particles, as expected from FNAL and ISR studies and from our result at 546 GeV. We obtain for the correlation slope 0.95±0.08±0.11 at 200 GeV and 1.09±0.09±0.13 at 900 GeV (first error is statistical and the second systematic). The investigation of photon-charged two-particle pseudorapidity correlations shows that these correlations are of short range and compatible with the observed charged two-particle pseudorapidity correlations. These correlations and the results for the average number of photons as a function of the produced number of charged particles favour the conclusion that photon sources other than π0 s contribute significantly to the observed photon yield in non single-diffractive p {Mathematical expression}-collisions. For example, if all photons are assumed to come from π0 s and η mesons, a η/π0 ratio of about 20% is inferred. © 1989 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe