I. Vorobiev

The characteristics of the L3 hadron calorimeter as realized in the observation of hadronic jets and other events from e+e− collisions at LEP are presented and discussed. The pattern-recognition algorithm utilizing the fine granulatiry of the calorimeter is described, and the observed overall resolution of 10.2% for hadron jets from Z decay is reported. The use of the calorimeter in providing information on muon energy losses is also noted.

The front-end electronics system for the anode signals of the CMS Endcap Muon cathode strip chambers has about 183,000 channels. The purposes of the anode front-end electronics are to acquire precise muon timing information for bunch crossing number identification at the Level-1 muon trigger system and to provide a coarse radial position of the muon track. Each anode channel consists of an input protection network, amplifier, shaper, constant-fraction discriminator, and a programmable delay. The essential parts of the electronics include a 16-channel amplifier–shaper–discriminator ASIC CMP16 and a 16-channel ASIC D16G providing programmable time delay. The ASIC CMP16 was optimized for the large cathode chamber size (up to 3×2.5 m2) and for the large input capacitance (up to 200 pF). The ASIC combines low power consumption (30 mW/channel) with good time resolution (2–3 ns). The delay ASIC D16G makes possible the alignment of signals with an accuracy of 2.2 ns. This paper presents the anode front-end electronics structure and results of the preproduction and the mass production tests, including radiation resistance and reliability tests. The special set of test equipment, techniques, and corresponding software developed and used in the test procedures are also described.

Configurations of sampling calorimeters with iron, lead and uranium as absorbers have been investigated using liquid ionization chambers as active elements. As liquid tetramethylsilane has been used. Results of beam tests with electrons, pions and muons in the energy range of 2 to 6 GeV are presented and compared with Monte Carlo simulations. In particular the questions regarding which configuration can compensate and the separation of sampling from intrinsic fluctuations have been studied.

Abstract The database system developed for the L3 experiment at the CERN large electron-positron (LEP) collider is described. The solution chosen has two components: a FORTRAN package (DBL3) and a system of distributed servers and data (L3DBSM). DBL3 provides basic database functions supplemented by facilities specific to high-energy physics experiments. The L3DBSM system, operational since the start of LEP data taking, has handled efficiently several hundred Mbytes of data over three different systems (VAX/VMS, IBM VM/CMS, Apollo Aegis SR10.x) and at eight different sites.

Abstract Results of experimental studies of the performance of the uranium calorimeter with gas sampling detectors are presented. There is further evidence showing the importance of the contribution of the neutron component of a hadronic shower to the detected signal. The response and the resolution of the uranium calorimeter are measured in the momentum range 0.3–6.0 GeV/ c for the different incident particles and different gases that are used in the detectors. For a calorimeter structure with double-gas-detector layers, the correlation between signals from two calorimeters formed by chambers filled with different gas mixtures is measured. The topics that are relevant to the performance of the L3 uranium-gas sampling calorimeter - such as its operation in the magnetic field, the energy dependence of muon response, the uranium noise, as well as the electronics optimization - are discussed.

A gas sampling calorimeter with uranium absorbers was built and tested in a beam of pions and electrons of 1 to 6 GeV/c. As far as the detection of electromagnetic showers is concerned, no difference between uranium and a conventional absorber is found. The energy dependence of the resolution of the calorimeter for hadrons is given for 4.5 and 9 mm sampling. The measured πe ratio is 0.83±0.03.

In the Compact Muon Solenoid (CMS) experiment, muon detection in the forward direction is accomplished by cathode strip chambers (CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using 36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge (MTCC) exercise conducted by the CMS experiment in 2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area (<0.01m2), results presented in this paper were obtained by many installed CSCs operating in situ over an area of ≈23m2 as a part of the CMS experiment. The efficiency of finding two-dimensional trigger primitives within six-layer chambers was found to be 99.93±0.03%. These segments, found by the CSC electronics within 800 ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System.

Abstract The design and the mass production of the proportional wire chambers for the barrel part of the uranium-gas sampling hadron calorimeter of the L3 detector at the CERN Large Electron-Positron storage ring (LEP) are described. The chambers meet the specific requirements arising from the limited space available to the calorimeter, the radioactivity of uranium, and the physics criteria of good energy and position resolution for incident hadrons. The mass production techniques employed ensured that all of the 371664 chamber cells have uniform response (with 5% accuracy) to ionizing particles. Over 8000 chambers of the same design, in 53 different sizes, were manufactured and tested at the ITEP (Moscow), at the University of Michigan (Ann Arbor) and at the IHEP (Beijing).

The production, installation, and testing of 468 cathode strip chambers for the endcap muon system of the CMS experiment played a critical role in the preparation of the endcap muon system for the final commissioning. Common testing procedures and sets of standard equipment were used at 5 international assembly centers. The chambers were then thoroughly retested after shipment to CERN. Final testing was performed after chamber installation on the steel disks in the CMS detector assembly building. The structure of the detector quality control procedure is presented along with the results of chamber performance validation tests.

This note gives an overview at a high conceptual level of the various databases that capture the information concerning the CMS detector. The detector domain has been split up into four, partly overlapping parts that cover phases in the detector life cycle: construction, integration, configuration and condition, and a geometry part that is common to all phases. The discussion addresses the specific content and usage of each part, and further requirements, dependencies and interfaces.

We describe the recent status of the CMS Endcap Muon System Cathode Strip Chambers (CSC), tests carried out and the performance of the system. Physical examples are given, stressing the importance of the subdetector both for first low luminosity physics and for the discovery potential of CMS.

Exclusive ρρ production in two‐photon collisions is studied at LEP for quasi‐real photons (γγ, centre‐of‐mass energies 161 GeV ⩽ s ⩽ 209 GeV, total integrated luminosity L=698 pb−1) and one virtual photon (γγ*, 89 GeV ⩽ s 209 GeV, L=855 pb−1). The cross sections of the ρρ production processes are determined as a function of the photon virtuality, Q2, and the two‐photon centre‐of‐mass energy, Wγγ, in the kinematic region: Q2 ⩽ 30 GeV2 and 1 GeV ⩽ Wγγ ⩽ 3 GeV.

This paper reviews searches for lepton flavour-changing neutral currents in Z decays at LEP. Presented results of all four LEP collaborations are preliminary.

Abstract Exclusive ϱ0ϱ0 and ϱ+ϱ− production in two-photon collisions for quasi-real photons and ϱ0ϱ0 production, involving highly virtual photons, was measured by the L3 experiment at LEP. The spin-parity-helicity analysis of ϱ0ϱ0 and ϱ+ϱ− systems at Q2 ≈ 0 was performed. A dominance of JP = 2+ and helicity 2 is observed. The cross sections of the process γγ ∗ → ϱ 0 ϱ 0 for 1.2

Exclusive rho rho production in two-photon collisions between a quasi-real, gamma, and a virtual, gamma*, photons is studied at LEP at centre-of-mass energies 89 GeV &lt; sqrt{s} &lt; 209 GeV with a total integrated luminosity of 854.7 pb-1. The cross sections of the gamma gamma* -&gt; rho rho processes are determined as a function of the photon virtuality, Q^2, and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 0.2 GeV^2 &lt; Q^2 &lt; 30 GeV^2 and 1.1 GeV &lt; Wgg &lt; 3 GeV.

At LEPII the study of the forward backward asymmetries of heavy quark production and the ratio of their production cross section with respect to hadrons, allows a further test of the electroweak predictions at the energies above the Z pole. The analysis techniques are discussed and the achieved results are reviewed.

Abstract

τ polarization results of four LEP experiments, published and preliminary, are reviewed. Measurements of τ polarization are performed using five main exclusive decay modes of τ lepton as well as inclusive methods. In the framework of the Standard Model the results can be interpreted as a measurement of the ratio of vector to axial-vector weak neutral couplings for electrons (g V e /g A e )eff=0.0690±0.0047 and for taus (g V τ /g A τ )eff=0.0705±0.0039 consistent with the e-τ universality. The effective electroweak mixing angle is determined to be sin2 0eff=0.2325±0.0008 if the universality is assumed.