Silicon detectors for neutrino oscillation experiments

This note describes the technique of using a target equipped with high resolution silicon microstrip detectors for the detection of the topological signature of decays in neutrino oscillation ex periments. Two detectors are presented. The first detector is installed in the NOMAD spectrometer at the CERN SPS neutrino beam. The target consists of four layers passive boron carbide plate s (total mass of 45 kg) interleaved with five layers of silicon microstrip detectors. A total of 600 single--sided silicon microstrip detectors are used amounting to a total area of 1.14 m$^2$. The silicon tracker is made with the longest ladders built to date (72 cm). During the 1997 run about 8000 charged current interactions were estimated to have occurred in the target and data tak ing will continue in 1998. For these events it will be possible to perform a precise measurement of both vertex and kinematical variables. The second detector was installed in September 1997 in a CERN PS pion beam to investigate the possibility of combining silicon detectors and nuclear emulsions. This detector consists of 72 single--sided silicon microstrip detectors with a total surfac e of 0.13 m$^2$ distributed over four layers, providing two measurements of each of the two orthogonal coordinates. This exposure will measure the precision with which the silicon tracker can p redict the position of particles in the emulsion. Both detectors provide invaluable experience towards the construction of a large scale silicon tracker for future neutrino oscillation experime nts.