[en] The general properties of jets produced in e/sup +/e/sup -/ annihilation are discussed. Multiplicities, rapidity correlations and jets fragmentation properties are studied for both the total one photon annihilation sample and for an enriched sample of two jet events, at a cm energy of 29 GeV. The data were obtained with the High Resolution Spectrometer at the PEP e/sup +/e/sup -/ colliding beam facility. The results correspond to an integrated luminosity of 106 pb/sup -/

[en] Four-jet events have been observed and studied by UA1, UA2 (CERN Collider) and CDF (Fermilab Collider) experiments. (orig./HSI)

[en] This group examined the processes with large cross sections, namely total cross sections, elastic scattering, particle production at low p/sub t/ and diffraction excitation. These are fundamental processes whose experimental study has always been one of the main aims of the physics program of each new accelerator in a new energy domain. The main features of these large cross section processes may be studied experimentally using relatively simple set ups at an early stage of phase I Isabelle operation. Luminosities of approx. = 10³⁰ cm^-2sec^-1 are quite adequate to perform precision experiments. Higher luminosities will be needed to study elastic scattering at larger angles, particles production at medium values of p/sub t/ and the production of new flavour. The large cross section processes are characterized by features which change slowly, logarithmically with c.m. energy (ln s physics). The new large range of energies which will become available at Isabelle will allow the possibility of performing a detailed study of the energy dependences of the processes under consideration. It will also be possible to perform detailed comparisons with similar experiments in anti pp collisions

[en] Experiment R210 has been designed with the primary aim of measuring precisely sigmasub(tot)(anti pp) and sigmasub(tot)(pp) over the ISR energy range. The experiment is also equipped with small-angle detectors which allow us to measure dsigmasub(el)/dt, and with a system of drift chambers and scintillation hodoscopes to measure charged multiplicities and angular distributions of emitted secondaries. Data have been collected at √s = 31, 53, and 63 GeV. Results at 53 GeV have already been published - results at 31 and 63 GeV must still be considered preliminary. (orig./HSI)

[en] The π⁰ inclusive cross section for c.m. production angles 0=90⁰ and 22⁰> or =theta> or =5⁰ at c.m. energies of √s-bar=23 and 53 GeV has been measured. This cross section is strongly dependent on both theta and √s-bar at small angles. The hypothesis of radial scaling is shown to be incapable of incorporating both theta and √s-bar dependence of the cross section. A recent quantum-chromodynamics calculation is in qualitative agreement with our results

[en] The UA2 jet vertex detector, a drift chamber with jet geometry, was successfully operated during the 1987 and 1988 CERN panti p Collider runs. A description of the chamber and a comparison between test-beam results and the chamber's performance during the Collider runs are given. (orig.)

[en] The vertex detector built by the Pisa Group for the CERN Intersecting Storage Rings muon pair experiment R 209 is described. A modular system of 136 small drift chambers, assembled around the ISR intersection region, measures the entrance directions of the muon pairs into the magnetized iron spectrometer, and the directions of the charged hadrons produced in association. Each module contains two doublets of sense wires, each doublet being associated with one delay line to determine directly the space points without left-right ambiguities. The mechanical structure is rather unconventional, having been designed with the aim of minimizing any dead space in the assembly of the modules. Space resolution is approximately +- 0.2 mm in the drift coordinate and approximately +- 2 mm in the delay coordinate. (Auth.)

[en] A detailed account is given of high-precision measurements of the total hadronic cross sections of proton-antiproton and proton-proton interactions at centre-of-mass energies of 30.6, 52.8 and 62.7 GeV. The experiment was performed at the CERN Intersecting Storage Rings (ISR) using the total interaction-rate method, in which additive correction terms for trigger losses were held to less than 6% of the final result. An experimental determination of the vertical beam-displacement scale permitted luminosity-monitor calibrations to be made with high intrinsic accuracy. The overall precision (systematic and statistical errors combined) achieved in the total cross section was +-1.1% for proton-antiproton reactions and 0.7% for proton-proton reactions. In the proton-proton case the measurement was the most precise such measurement made at the ISR. (orig.)

[en] A description of the response of the NOMAD electromagnetic calorimeter to electrons and photons is discussed. In particular, the dependence of the two-dimensional shower shape on the angle and energy of the incident particle is parametrized by analytical functions. Some applications to the neutrino event reconstruction are also reported

[en] We measured the differential cross section for anti pp and pp elastic scattering in the momentum-transfer range 0.01 < vertical stroke t vertical stroke < 1.0 GeV² at the CERN Intersecting Storage Rings with center-of-mass energy √s = 52.8 GeV. Fitting the differential cross section with an exponential [A exp (bt)], we found bsup(anti pp) = 13.92 +- 0.59 GeV^-2 for vertical stroke t vertical stroke < 0.05 GeV², whilst for vertical stroke t vertical stroke < 0.09 GeV², bsub(anti pp) = 10.68 +- 0.26 GeV^-2. Using the optical theorem, we obtained for the total cross section sigmasub(tot)(anti pp) = 44.86 +- 0.78 mb and, by integrating the differential cross section, we obtained for the total elastic cross section sigmasub(el)(anti pp) = 7.89 +- 0.28 mb. Calculations of sigmasub(tot) combining elastic-rate and total-rate measurements are also given. All of these measurements were also performed for pp scattering at the same energy, and the results for both reactions are compared. (orig.)