A. Frenkel

A-dependence of the charm production cross section in 300 GeV/c proton interactions

Abstract The A-dependence of the charm production cross section is determined by measuring the yield of prompt single muons in a beam-dump experiment, using a 300 GeV/c proton beam on Al, Fe, and U targets. Assuming that the production cross section varies as Aα, we obtain α(μ+) = 0.79±0.12 and α(μ−) = 0.76±0.13 in the kinematical region xF≳0.1 of the charm.

The production of beauty particles in π−-U interactions at 320 GeV energy

Abstract B B production in π − -uranium interactions has been observed at 320 GeV beam energy looking at events with three muons in the final state. The cross section is found to be σ B B = 4.5±1.4±1.4 nb per nucleon (for a linear A -dependence) or σ B B = 17.6±5.5±5.5 nb per nucleon (assuming A 0.75 dependence). An estimate of x F distribution is given.

STUDY OF CHARM CORRELATIONS IN PI(-)-N INTERACTIONS AT ROOT-S-APPROXIMATE-TO-26 GEV

Abstract We report on the associated production of charmed hadrons in π−-nucleon interactions at s ≃26 GeV at the CERN Ω′ spectrometer. Results on the azimuthal correlation of charmed particle pairs are presented and compared to the predictions of Next-to-Leading-Order QCD calculations.

BB inclusive cross section in 320 GeV π−-uranium interactions

Abstract The inclusive cross section for B B production by 320 GeV π− on uranium has been measured, assuming different production models and a variable amount of B0− B 0 mixing. A comparison of our results with those of the NA10 Collaboration is performed. The J/Ψ inclusive production cross section has also been measured in our experiment and agrees well with existing data, thus confirming the accuracy of our overall normalization.

A Muon Spectrometer With Calorimeter Dump Used for the Beauty Search at the {CERN} Super Proton Synchrotron

Abstract A detailed description is given of the WA78 apparatus, which combines a dump calorimeter and a muon spectrometer and is used to measure the cross-section for B B production by a high-intensity 320 GeV π − beam. The performance of the various parts of the equipment is discussed. In particular, we consider all the problems related to the calorimetric measurement in high-rate conditions.

WA92: A fixed target experiment to study beauty in hadronic interactions

Abstract The essential feature of the described experimental techniques is the use of two specially designed pieces of hardware: a high precision “decay detector” and a fast secondary vertex trigger processor. Experiment WA92 should be able to obtain a sufficient data sample to measure lifetimes of B ± and B 0 and the B hadroproduction cross section.

Search for the decay D0 ---> mu+ mu-

Abstract We have searched for the decay D 0 → μ + μ − among 1.25 × 10 5 μ + μ − pairs produced by 350 GeV/ c π − particles interacting in copper and tungsten targets. Using a high-resolution silicon-microstrip detector followed by a large-acceptance magnetic spectrometer and a muon filter we are able to discriminate between prompt and non-prompt muons and to measure dimuon masses. No candidate compatible with a D 0 → μ + μ − decay has been found, allowing us to set an upper limit on the branching fraction B( D 0 → μ + μ − ) of 7.6 × 10 −6 at the 90% confidence level.

Use of a high-resolution, scintillating-fibre, tracking detector in recording π−-nucleon interactions at √s ≈ 26 GeV

Abstract A scintillating-microfibre, tracking detector has been used at the CERN Omega spectrometer to record the interactions of 340 GeV/ cπ − particles incident on a fixed target. The detector - based on coherent bundles of ∼36 μ m diameter, PMP-doped plastic fibres - was oriented so as to give views of interactions in the plane perpendicular to the incoming pions. Additional event information was provided by a series of 20 and 50 μm pitch silicon-microstrip detectors, placed near to the fibres, and by the spectrometer. An account is given of the contribution of the scintillating-fibre device in obtaining full event reconstruction.

Hadroproduction of BB pairs in π− U interactions at 320 GeV energy

Abstract A signal from B B associated production in π − Uranium interactions at 320 GeV, has been observed looking at events with three muons and two like-sign muons in the final state. The experimental energy and p T distributions of muons as well as the total cross section are in good agreement with QCD predictions.