J.P. Richeux

The L3 silicon microvertex detector

Abstract The design and construction of the silicon strip microvertex detector (SMD) of the L3 experiment at LEP are described. We present the sensors, readout electronics, data acquisition system, mechanical assembly and support, displacement monitoring systems and radiation monitoring system of the recently installed double-sided, double-layered SMD. This detector utilizes novel and sophisticated techniques for its readout.

First-level charged particle trigger for the L3 detector

Abstract A first-level charged particle trigger based on parallel processing and look-up tables has been developed for the L3 detector. It processes analog signals generated by the central tracking detector, a drift chamber with axial wires. The trigger decision is made on the total number of tracks, the number of coplanar pairs of tracks, or on more complicated topologies found in the projection normal to the beam axis. The system is very flexible and can be adjusted to a wide range of background conditions and tracking chamber efficiencies.

The L3 Silicon Microvertex Detector: installation and results on 1993 performance

Abstract The status of the Silicon Microvertex Detector (SMD) and its installation into the LEP-L3 experiment are presented, highlighting novel features and sophisticated techniques. Preliminary results based on 1993 data are given and compared with Monte Carlo predictions, to understand the detector performances and its tracking capabilities.

High pT trigger electronics for a large orthogonal readout electromagnetic calorimeter

Abstract A trigger system has been designed and built to select events containing high p T electromagnetic showers detected in a large calorimeter with orthogonal readout. The electronics include analog adders with up to 123 inputs, pulse shapers with 20 ns integration time, 100 MHz flash ADCs and ECL loop-up tables. The total number of input channels is 3072 and the trigger decision is made in about 120 ns.

A silicon microstrip tracker in space: Experience with the AMS silicon tracker on STS-91

SummaryThe Alpha Magnetic Spectrometer (AMS) is designed as an independent module for installation on the International Space Station (ISS) in the year 2003 for an operational period of three years. The principal scientific objectives include the searches for antimatter and dark matter in cosmic rays. The AMS tracker uses silicon microstrip sensors to reconstruct charged-particle trajectories. A first version of the AMS, equipped with 2.1 m2 of silicon sensors and a permanent magnet, was flown on the NASA space shuttle Discovery duringJune 2–12, 1998. In this contribution, we describe the detector and present results of the tracker performance duringthe flight.

A GEM based TPC with two large 3-GEM Towers

A large size prototype of a TPC with GEM amplification has been successfully built and operated. To obtain an active area larger than the one provided by the largest GEM foil on the market, 2 independent GEM towers have been hosted on a single pad plane minimising the dead space between the towers. This readout structure has been inserted in a test-bed available at CERN, inherited from the HARP-TPC installation at the PS East Hall, made by a cylindrical field-cage of 80 cm diameter and around 150 cm active length, all placed inside a solenoid magnet capable of 0.7 T. This setup is equipped with about 1500 readout channels. The initial choice for relatively large squared pads (8mm) is driven by the need to study the performances in view of a neutrino oscillation experiment, where the track density is low. A systematic study of the performances has been performed as a function of several parameters like the operating voltages of the GEM towers, the magnetic and the drift fields and the gas mixture. Special care has been taken in the study of the gas, with a large range of mixtures including Ar:CF4:iC4H10.

THE NEW LEVEL-1 TRIGGER FOR THE FORWARD TAGGER OF THE L3 EXPERIMENT

Abstract A fast level-1 trigger processor for the Active Lead Ring calorimeter (ALR) and for the Very Small Angle Tagger (VSAT) of the L3 detector has been constructed and implemented. The main application is the study of single tagged two-photon collision processes at LEP II. Particular care has been taken to preserve the timing characteristics of the signal in order to allow bunch tagging in the multi-bunch mode of LEP.

Status of the L3 silicon microvertex detector

Abstract A report on the status of the construction of the L3 Silicon Microvertex Detector is presented here. The detector will consist of two double sided AC coupled silicon layers equipped with rφ and z readout with an expected intrinsic resolution of ≈ 6 μ m and ≈ 25 μ m respectively. A description of the detector with its mechanical support, alignment system and readout electronics is presented.

TPG, test results

TPG is the acronym for Time Projection Chamber with GEM amplification, high-granularity hexaboard read-out and FADC electronics. We have constructed a TPG read-out module, called TPG-head, with three GEM foils and a multilayer board, called hexaboard, covered with 710 000 hexagonal pads of 300 mum size. The total active area of this module is a disk of 30 cm diameter. The 710 000 pads are read by three sets of 576 strips dephased by 120 degrees. Each strip is read by a FADC channel with 100 ns sampling time. The module is mounted in a test-bed formed by a cylindrical field cage of 80 cm diameter and 150 cm length inside a solenoidal magnet that operates with a magnetic field up to B=0.7 Tesla. Tests with X-ray sources show an intrinsic spatial resolution of the order of 40 mum. The threshold for transverse momentum measurement of low energy tracks is below 0.1 MeV/c with a magnetic field of 0.07 Tesla. At 0.7 Tesla the intrinsic space point resolution of the chamber is such that the error on the measurement of the transverse momentum is DeltaPtsime0.1 MeV/c in absence of distortions from the drift region

A multi-hit ADC and TDC for the charged particle trigger of the L3 experiment☆

Abstract A Fastbus ADC and TDC module has been developed for the trigger of the L3 experiment. It provides fast and precise integration of successive pairs of charges derived from the charge division wires of the central tracking chamber, as well as a measurement of their drift times. The minimum separation time between digitizations is 170 ns. The charges are measured with a precision of 1 pC up to charges of 600 pC. The drift times are measured in 50 ns time bins. A system including 60 modules provides data allowing the reconstruction of charged particle tracks in three dimensions. This information is used in background rejection algorithms of the second and third level triggers.