Search

Measurements of the behaviour of various high-resolution silicon strip detectors with capacitive charge division have been made in a high-energy particle beam. The results are compared with an electrostatic model which calculates the charges deposited on the strips after the passage of a minimum ionizing particle. Good agreement is found and the model is used to propose a method of improving the charge-division properties of such detectors.

A search has been made for the hadronic production of charmed baryons and mesons with a large aperture forward magnetic spectrometer using 150 GeV protons originating from the CERN-SPS. A prompt electron trigger was used as a signature for charm. Upper limits at 90% confidence level have been obtained for the production of Λ c + D 0 , D 0 D + and D − : σ(Λ c ) ⩽ 8 μ b , σ( D 0 ) ⩽ 64 μ b , σ( D 0 ) b , σ( D + ) ⩽ 51 μ b and σ( D − ) ⩽ 49 μ b per nucleon, assuming linear A dependence. Systematic errors due to uncertainties in branching ratios and to model dependence of the acceptance calculation are discussed.

We have observed three unique decays of F mesons into KK π and five unique decays of D mesons into KK π using the NA11 spectrometer together with a telescope of high-resolution silicon microstrip detectors. The mass value obtained for the F meson is (1975 ± 4) MeV, the lifetime (3.2± 1.3 3..0 )×10 −13 s.

A telescope consisting of six silicon microstrip detectors achieving 5 μm spatial resolution for minimum ionizing particles has been built. The design and fabrication of the counters, electronics, and mechanical set-up is described, and first results of its performance in a 175 GeV/c beam are reported.

The charge collection in silicon detectors has been studied, by measuring the response to high-energy particles of a 20 μ pitch strip detector as a function of applied voltage and magnetic field. The results are well described by a simple model. The model is used to predict the spatial resolution of silicon strip detectors and to propose a detector with optimized spatial resolution.

High precision silicon detectors, developed for the measurement of short lived particles are described, and first results on their performance are reported.

Based on the drift chamber principle a low capacity diode has been built with one large area p+n junction at the front, and p+ and n+ patterns at the rear. The capacitance of the device is only 1.5 pF at an area of 1 cm2 and a thickness of 280 μm. The energy resolution for Am α-particles is 13.5 keV, the optical sensitivity is homogeneous over the whole area, and the charge collection times lie between 10 and 300 ns.

A pressurized drift chamber is described which measured particle tracks at 10 points. For particles in a beam of low intensity, an accuracy of 23μm per point is obtained. Downstream of a target in a high-intensity beam, events are reconstructed with an accuracy of 30 μm per point.

A silicon detector telescope with 5 μm spatial resolution has been developed and successfully used to select charmed particles produced in high energy hadron collisions. A brief review of the properties and the performance of the system is given.