A. Contin

Evidence of the same multiparticle production mechanism in p−p collisions as in e+e− annihilation

Abstract The split-field magnet spectrometer at the CERN intersecting storage rings was used to measure, in p−p collisions at s 62 GeV , the inclusive momentum distribution of the charged particles produced in the same hemisphere as the leading proton ( x >0.4). A new scaling variable was introduced in order to take into account baryon-number conservation effects in p−p interactions. It is shown that distributions in this variable are in good agreement with the momentum distribution of the hadrons produced in e + e − annihilation. The results suggest that the multiparticle production mechanism in p−p collisions is the same as in e + e − provided that the effects of baryon-number conservation are removed.

The energy dependence of charged particle multiplicity in p-p interactions

Abstract The average charged multiplicity in proton-proton interactions has been studied at √ s = 62 GeV. A very good agreement with the average charged multiplicity measured in e + e − annihilation at different energies is obtained by redefining, in p-p, the correct energies available for particle production. This means that a p-p collision at √ s = 62 GeV does in fact correspond to a large range of effective hadronic energies available for particle production.

Measurements of in and out distributions in high-energy pp interactions

ConclusionsThe results of the present paper show that the « planarity » effects observed in the multiparticle systems produced in (e+e-) annihilations (1) are also present in the multiparticle systems produced in pp interactions. This means that the analogy already reported between pp interactions and (e+e-) annihilations, i) in the inclusiveXR* distributions (2) and ii) in the average charged-particle multiplicity (7),does in fact hold also iii) for the « planarity » structure of the multiparticle systems produced.

The ratio of charged-to-total energy in high-energy proton-proton interactions

Abstract The ratio of charged-to-total energy in multiparticle hadronic systems produced in pp interactions has been measured. The analysis has been performed using our technique of subtracting the “leading” baryon effects. The results are compared with e + e − annihilation data.

A large-area time-of-flight system for a colliding beam machine

Abstract We describe the performance of a large solid-angle (2 sr) time-of-flight system used in conjunction with the Split Field Magnet spectrometer of the CERN Intersecting Storage Rings (ISR). The system consists of a hodoscope of 67 scintillator counters, at a distance of about 5 m from the beam intersection. The ISR being a coasting beam machine, contrary to the tightly bunched e + e − machines, the event time is unknown and therefore a special analysis procedure for particle identification is required. We illustrate a powerful statistical method which allows the identification, with more than 90% efficiency, of pions up to about 1 GeV/c, kaons up to about 1.4 GeV/c, and protons up to about 2 GeV/c.

Failure modes of large surface avalanche photo diodes in high-energy physics environments

Large area avalanche photo diodes (APD), a new and very promising type of light detector, were tested at high gain on a beam line and suddenly failed. A detailed study of the failure modes showed that these dc vices, if used at low gain and with special carl, may actually be used in high-energy physics environments and indicates the road of development toward radiation hard, large area APDs, No problem was found when APDs are operated in absence of highly ionizing particles

The leading effect explains the charged-particle multiplicity distributions observed at the cern pp collider

SummaryThe assumption that the leading effect, and the charged-particle multiplicity distributions, measured at the ISR, scale with energy, and that the mean charged multiplicity, measured at the ISR, can be extrapolated up to Collider energy using the leading subtraction method, allows a prediction of the charged multiplicity distribution at the CERN pp Collider. This prediction is found to be in excellent agreement with the experimental data obtained at the Collider by the UA5 group.

Measurement of forward and backward mean charged-particle multiplicities in high-energy (pp) soft interactions and comparison with high-energy neutrino and antineutrino deep inelastic scattering

SummaryThe difference between forward and backward mean charged-particle multiplicities is shown to exist also in (pp) interactions, when these are analysed in analogy with the deep inelastic scattering method. The measurements reported here show that this difference, which has been observed for a long time in (vp) and (vp) deep inelastic scattering experiments, is explained in terms of the omitted correction for the leading effect in the backward hemisphere.

Scaling in the charged-particle multiplicity distributions at the ISR and comparison with (e+e-) data

SummaryThe distribution of the charged-particle multiplicities at the ISR are studied in terms of the effective energy available for particle production in (pp) interactions. These distributions are found to scale once the effective energy, obtained via the leading subtraction method, is used. A comparison with the charged particle distributions measured in (e+e-) annihilation shows a clear difference. This could be interpreted in terms of gluon-induced and quark-induced jets; where the gluoninduced jets are characterized by a wider multiplicity distribution with respect to quarkinduced jets.

Results on lead/scintillating fibres calorimetry

Abstract In the framework of the LAA project at CERN, the RD25 R&D group has built a fully projective, integrated electromagnetic and hadronic, lead/scintillating fibres compensating calorimeter prototype. The prototype consists of 41 modules, each made of a straight (or electromagnetic) and two wedged (or hadronic) sections, with a lead to fibres ratio of 4 to 1 in volume. We describe in this paper the performances of the calorimeter exposed to high energy electron and pion beams: results are presented on electromagnetic and hadronic energy resolution, position resolution and particle/particle separation in space. Prototype construction required the development of a technology, also described in this paper, which is directly scalable to the construction of a 4 π detector, intended to measure, localize and identify particles in a multi-TeV hadron collider experiment.