P. T. Cox

Observation of jet structure in high transverse energy events at the CERN intersecting storage rings

Abstract The spectrum d N d E T 0 ( E T 0 = neutral transverse energy) has been measured with an electromagnetic calorimeter covering 90% of 2 π in azimuth. The measurement, performed in pp collisions at s = 62 GeV , covered the E T 0 range from 10 to 30 GeV. Evidence is presented that a large fraction of these events are jet-like, the fraction increasing with E T 0 .

Observation of KNO scaling in the neutral energy spectra from αα and pp collisions at ISR energies

Abstract Neutral transverse energy spectra in pp and αα interactions are analyzed in terms of the wounded nucleon model. Analysis of the αα spectrum by application of a multiple nucleon-nucleon collision mechanism is conveniently performed when a gamma distribution is used to represent the pp spectral shape. The wounded nucleon model provides a reasonable description of the αα spectrum for the first three orders of magnitude, but completly fails to account for the slope of the high energy tail of the distribution. However, the pp and αα spectra can both be fitted to the same gamma distribution when scaled by their respective mean values and thus exhibit KNO scaling.

Direct photon cross sections in proton-proton and antiproton-proton interactions at s=24.3 GeV

Abstract We report results on inclusive direct photon (γ),π0, and η production in both pp and pp interactions at s =24.3 GeV in the transverse momentum range 4.1≤pT≤7.7 GeV/c and rapidity range −0.1≤y≤0.9. The data were collected between 1988 and 1990 by the UA6 experiment at CERN, which employed an internal H2 gas jet target in the SppS collider. The inclusive direct photon cross sections and the cross section difference σ( p p )−σ( pp ) expressed as functions of pT(γ) are compared with next-to-leading order QCD predictions.

Direct photon production at the CERN ISR

Abstract A measurement of direct photon production in pp collisions at a center of mass energy ∝ s =63 GeV is reported. Arrays of lead-glass calorimeters and multiwire proportional chambers were used as photon detectors. Data are presented in the transverse momentum range from 4.5 to 10 GeV/ c and compared with QCD predictions. The event structure of this sample is compared with that of a set dominated by high transverse momentum π O s .

Jets in high transverse energy events at the CERN intersecting storage rings

Abstract Most events with high neutral transverse energy, ET0, produced in pp colisions at √s = 62.3 GeV, are jet-like. The evidence for this is presented, based on data collected using an electromagnetic calorimeter covering 90% of 2π in azimuth. The spectrum dN/dET0 has been measured over the ET0 range from 10 to 35 GeV. Properties of the observed jets are discussed.

High pT π0 production from αα and αp collisions at the CERN ISR

Abstract The invariant cross sections for π0 meson production in alpha—alpha and alpha—proton collisions at the ISR were meas- ured up to transverse momenta of 7 GeV c and 8 GeV c , respectively. These measurements are compared with π0 production in pp collisions at the same values of s / nucleon, and the variation of the nuclear A-dependence with pT is determined.

A study of e+e− pairs in the mass range 11 to 25 GeV/c2 at the CERN intersecting storage rings

Abstract A sample of 58e + e − events with an invariant mass greater than 11 GeV/c 2 produced in pp collisions at a centre-of-mass energy of 62.3 GeV is discussed. The cross sections are presented as a function of the mass and transverse momentum. The electron pairs produced with a mean transverse momentum of 2.50 ± 0.25 GeV/ c .

A comparison of the production of π0-mesons in pp and pp interactions at the CERN ISR

Abstract A comparison of p p and pp interactions s =52.7 GeV at the CERN ISR. The quantities compared were the charged and neutral multiplicities, the total neutral transverse energy, ΣET, up to 12 GeV, and the single π0 inclusive cross section up to p T = 5 GeV c . No significant differences were observed.

A study of associated particles and second-order processes in electron-pair production at the CERN intersecting storage rings

Abstract The multiplicity of particles associated with electron pairs with mass greater than 11 GeV/c 2 is found to increase with the transverse momentum p T of the electron pair. The associated particles are observed to recoil against the electron pair and compensate locally its transverse momentum. The data are compared with lower √ s dimuon data using the scaling form: s 2 p T 2 (d 3 σ /d y d p T 2 d m 2 ) = H ( x T , y , τ ).

Search for polarization in

Inclusive hyperon production by 400 GeV protons at Fermilab has shown that the hyperons are produced with significant polarization. However no polarization has been seen for Λ’s produced at these energies. In this paper we present the results of a searcch for Ξ0 polarization.