A. Gougas

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.

An antimatter spectrometer in space

Abstract We discuss a simple magnetic spectrometer to be installed on a satellite or space station. The purpose of this spectrometer is to search for primordial antimatter to the level of antimatter/matter ≈10 −9 , improving the existing limits obtained with balloon flights by a factor of 10 4 to 10 5 . The design of the spectrometer is based on an iron-free, NdFeB permanent magnet, scintillation counters, drift tubes, and silicon or time projection chambers. Different design options are discussed. Typically, the spectrometer has a weight of about 2 tons and an acceptance of about 1.0 m 2 sr. The availability of the new NdFeB material makes it possible for the first time to put a magnet into space economically and reliably.

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.

A long base line RICH with a 27 kton water target and radiator for detection of neutrino oscillations

A 27 kton water volume is considered as a target for a long base line neutrino beam from CERN to Gran Sasso. Charged secondaries from the neutrino interactions produce Cherenkov photons in water which are imaged as rings by a spherical mirror. The photon detector elements are 14 400 photomultipliers (PMs) of 127 mm diameter with single photon sensitivity. A coincidence signal of ≈300 PMs in time with the SPS beam burst starts readout of the PMs in bins of 1 ns over a period of 100 ns. This defines the effective detector granularity to be 1.44 Mpixels, quite sufficient for the maximum expected event size of ≈2 × 104 photon hit points. Momentum, direction and velocity of hadrons and muons are determined from the width, center and radius of the rings, respectively. Momentum is measured if multiple scattering dominates the ring width, as is the case for most of the particles of interest. Thresholds in water for muons, pions, kaons and protons are 0.12, 0.16, 0.55 and 1.05 GeV/c, respectively. Momentum resolutions of 1–10%, mass resolutions of 5–50 MeV and direction resolutions of <1 mrad, are achievable. Electrons and gammas can be measured with energy resolution σE/E≈7%/E(GeV) and with direction resolution ≈1 mrad. The detector can be sited above ground because it is directional and the SPS beam is pulsed thus it has excellent rejection of cosmic ray background.

Results of a first beam test of hadron blind trackers

Abstract We describe the experimental results of a new type of electron tracker, called Hadron Blind Detector or HBD. An HBD prototype was tested with gas mixtures of CF4 with He or Ne and a parallel plate avalanche chamber having a CsI photocathode of eight pads. Beam tests confirm the large Cherenkov light bandwidth in the EUV region that can be obtained with such gas mixtures. It results in a large quality factor of about 500 cm−1 which allows HBD operation with a much shorter radiator thickness than conventional Cherenkov counters. Full electron efficiency was obtained, while pions were rejected up to momenta of 9 GeV/c. HBD is unique in measuring electron trajectories near the vertex, vetoing Dalitz pairs, and providing trigger on electrons among heavy hadron background. We discuss the use of such detectors for lepton identification and detection in high energy physics experiments and especially in heavy ion colliders.

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.

Performance of the L3 plastic scintillating fibre calibration system

Abstract The L3 plastic scintillating fibre system is used to calibrate the central tracker by providing an external measurement of the track position in the bending plane. We describe the performance of the system during the LEP runs of 1989–1995 on the Z and the results of the calibration using the PSF system.

The design and construction of a double-sided silicon microvertex detector for the L3 experiment at CERN

A silicon microvertex detector (SMD) has been commissioned for the L3 experiment at the Large Electron-Positron colliding-beam accelerator (LEP) at CERN. The SMD is a 72,672 channel, two layer barrel tracker that is comprised of 96 ac-coupled, double-sided silicon detectors. Details of the design and construction are presented. >

1994 running experience with the L3 Silicon Microvertex Detector

The 1994 running experience with the L3 Silicon Microvertex Detector is described; in particular we report on the detector performances observed during the year (namely the DAQ and detection efficiency and the signal to noise ratio) and on the reduction of the noise affecting the detector.

Spatial resolution of wedge shaped silicon microstrip detectors

Abstract Several wedge-shaped silicon microstrip detectors with pitches from 30 to 100 μm have been designed by our group and beam tested at the CERN SPS. We find the spatial resolution σ becomes larger at the rate of 0.21 μm per 1 μm increase in pitch, but the number of strips per cluster remains about the same as the pitch varies from 30 to 100 μm.