Bottom Production in Two-Photon Collisions at LEP

Results on inclusive and exclusive bottom production in gammagamma collisions are presented. The total cross section of inclusive bottom production is investigated through its leptonic decays at LEP II energies by the experiments L3 and OPAL. The average cross section, after correction for acceptances and efficiencies, is sigma_tot = 13.3 +- 1.5 +- 2.3 pb. The next-to-leading order calculations are lower than the data by a factor three, which corresponds to a difference of more than three standard deviations. ALEPH studied the exclusive bottom production. Searching for the eta_b one candidate is found. Limits on Gamma_gammagamma(eta_b)*BR for 4 and 6 charged particles are extracted. The candidate has a mass of 9.30 +- 0.04 GeV.Comment: 4 pages, Submitted to proceedings of the Conference: DIS01, Bologn

Heavy Flavour Production in Two-Photon Collisions at LEP

New results from the experiments ALEPH, DELPHI, L3, and OPAL on heavy quark production in gammagamma collisions are presented. Inclusive charm and bottom production are investigated at LEP~2 energies. The total and differential cross sections for charm quarks are now measured by all four LEP collaborations, the total bottom by two. Charmonia are studied inclusively via the muonic decay of the J/psi and separated for the resolved and diffractive processes. New results are available for exclusive production of the eta_c meson. First searches for exclusive eta_b production are presented.Comment: Presented at the DIS2002 conference in Cracow, Poland; to be published in Acta Physica Polonica B; 7 page

Photon Structure and Heavy Flavour Production in gammagamma Collisions at LEP

New results reported at the Moriond-QCD 2003 conference from the experiments ALEPH, DELPHI, L3, and OPAL on the structure of the photon as well as heavy quark production in gammagamma collisions are presented. The hadronic structure of the photon is studied in single-tagged events; the interaction of two virtual photons is investigated in double-tagged events. Di-jet events allow, besides constraining the photon structure, investigations on the structure of jets, measurement of the di-jet as well as inclusive and differential cross sections. Inclusive charm and bottom production are investigated at LEP~2 energies. The total and differential cross sections for charm quarks are now measured by all four LEP collaborations, the total bottom by two. Charmonia are detected inclusively via the muonic decay of the J/psi and separated for the resolved and diffractive processes. Updated results are available for exclusive production of the eta_c meson. The search for exclusive eta_b production is presented.Comment: Presented at the 38th Rencontres de Moriond on QCD and High-Energy Hadronic Interactions, Les Arcs, France, 22-29 Mar. 2003; 5 page

Search for eta_b in Two-Photon Events

A search for the pseudoscalar meson eta_b was performed at LEP~II energies with an integrated luminosity of 700pb^-1. The search, done for the decay modes into 4 and 6 charged particles yielded 0 and 1 candidates, respectively. Upper limits on Gamma_gammagamma(eta_b)*BR for both modes of 57eV and 128eV were obtained with corresponding limits of 17% and 38% on branching ratios BR(eta_b) -> 4 charged particles and BR(eta_b) -> 6 charged particles at a confidence level of 95%. The candidate has a mass of 9.30 +- 0.04GeV.Comment: 4 pages, Submitted to proceedings of the Conference: PHOTON 2001, Ascon

Summary of Photon 2001

This article summarizes the experimental and theoretical results presented and discussed at the International Conference on the Structure and Interactions of the Photon, PHOTON 2001, in Ascona.Comment: 29 pages, Summary of the Photon 2001 conference held in Ascona, submitted to proceeding

Particle detectors

This comprehensive book provides a detailed introduction to the principles of particle detectors used in physics, biology and medicine. Introductory chapters review the interactions of particles and radiation with matter, introduce the principles of and define different types of measurement and their units. The main body of the book encompasses all currently used detectors and counters. Each description covers basic principles, potential uses and limitations. The scope of the book includes detectors for ionization and track measurement, methods for time, energy and momentum measurement, and for particle identification. Two chapters are about electronics (readout methods, monitoring, data acquisitio A final chapter gives examples of detector systems. The book concludes with a detailed glossary of terms, tables of units and physical constants and a detailed reference list