H. Hofer

Hadron calorimetry in the L3 detector

Abstract 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.

A high resolution spectrometer for the study of high mass muon pairs produced by intense hadron beams

Abstract We describe the design, construction and performance of a high-resolution spectrometer used at CERN to study the production of high-mass muon pairs by intense hadron beams. We also discuss the on- and off-line software used with this spectrometer.

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 time expansion chamber as a vertex detector for the experiment mark j at desy

Abstract The design and results from a beam test for a small vertex detector, now installed in the DESY MARK J experiment, are presented. The concept of this drift chamber is based on the time expansion principle with readout planes inclined to solve the left-right ambiguity. A spatial resolution of 35 μm, varying weakly as a function of drift length and azimuthal angle, has been achieved.

A TIME EXPANSION CHAMBER AS A VERTEX DETECTOR

Abstract A high-resolution drift chamber based on the time expansion principle has been built as a vertex detector for the Mark J experiment at DESY. The chamber design and the associated control and readout system are described. Results on chamber performance obtained from test beam measurements and first results from running at PETRA are reported.

A-dependence of muon pair production in π-nucleus interactions at 280 GeV/c

Abstract We have measured the relative cross sections for muon pair production by 280 GeV/ c negative pions on three different targets: carbon, copper, and tungsten. The value of α obtained from the parametrization σ = constant × A α is 0.94 ± 0.02 ± 0.02, whereas the parametrization σ≈σ 0 ( Z A ) A α′ , where σ 0 ( Z A ) is given by the Drell-Yan model, leads to α ′ = 0.97 ±0.02±0.02. This last result is in agreement with the quark additivity rule which is inherent in the Drell-Yan model, no dependence is observed on the transverse momentum of the muon pair.

A readout system for plastic scintillating fibers

Abstract A readout system for plastic scintillating fibers has been developed using a multi-anode microchannel photomultiplier tube operated in a 5 kG magnetic field and the CMOS MX4 microplexer chip. The microchannel photomultiplier tube with an anode array of 10×10 is coupled to an array of fibers using a precise alignment procedure. Each readout unit is capable of sampling signals from 100 fibers simultaneously and multiplexing the analog signals serially with rates of up to 5 MHz. The analog signals are subsequently digitized and subtracted from the pedestals previously stored using a specially designed analog to digital VME module. Such a readout system has many applications in high energy physics, solid state physics, and other fields where a large number of fibers must be read out in short times and at relatively high rates.

A study of the dimensional stability of the AMS silicon tracker

The Alpha Magnetic Spectrometer (AMS) is designed as an independent module for installation on the International Space Station (ISS) for an operational period of 3 years. The AMS is the first cosmic ray spectrometer equipped with a large area silicon tracker . A preliminary version of the detector was flown on the NASA space shuttle Discovery during June 2–12, 1998. Results for the dimensional stability of the silicon tracker planes based on the flight data, and the metrology data recorded before and after the flight, are presented.

Formation of the lightest muonic atoms in low density gases

Abstract A novel technique devised to produce light muonic atoms efficiently in low pressure gases (10 to 600 torr at 300 K) has been successfully implemented in helium. Muons produced by in-flight decay of 40 MeV/ c pions are trapped in a magnetic bottle filled with the low density gas. The high-yield formation of muonic atoms is demonstrated by detecting the characteristic X-rays as well as the μ-decay electrons.

The L3 vertex detector: design and performance

Abstract The L3 vertex detector is comprised of the time expansion chamber (TEC), the Z -chamber and a layer of plastic scintillating fibers. The TEC has shown a high spatial resolution and an excellent multi-track reconstruction capability at LEP luminosity. The Z -chamber provides information about the z -coordinates of the tracks and the fibers are used for calibrating the drift velocity with a high precision. A description of the L3 vertex detector, its readout and data acquisition and its performance during the 1990 LEP running period is presented in this paper.