Microvertex detectors, present trends and future perspectives

The need of resolving complex track configurations and reconstructing vertices in modern high energy experiments is conveying a growing effort into the design of a relatively young item, called microvertex detector. The microvertex detector is obtained by arranging several position sensitive units of high spatial resolution in a suitable geometric configuration. The present paper aims at reviewing different structures of microvertex detectors that are already operating in fixed target experiments or that are being designed for future colliders. The constraints they have to cope with, the implemented functions, the accuracy achievable, the readout employed and the impact of radiation damage on their behaviour will be critically analyzed. Possibilities opened up by new position-sensing elements will be investigated. The use of micro-vertex detectors in future experiments at large hadron colliders will also be considered and the constraints arising from these peculiar applications will be discussed.