Characterization of strip detector parameters for the SuperB Silicon Vertex Tracker

Abstract

The Silicon Vertex Tracker for the SuperB detector is designed as an evolution of the BaBar SVT, based on double-sided strip detectors. The wider acceptance in polar angle (down to 300 milliradians) will imply larger incidence angles (up to 73°) on the sensors. On the z-side (reading out the z coordinate, along the beam direction) this results in large clusters with small signal values on individual channels. For optimum performance it would be desirable to continuously vary the sensor pitch on z-side versus position. An easy and convenient way to approximate this configuration is to bond two or three adjacent strips to a single trace of the fanout circuit that connects the strips to the front-end electronics (the so-called ‘pairing’ option). In order to accurately measure the total capacitance of strips in various pairing configurations (×2,×3,×4) two test detectors have been assembled on PCBs, and various strip connection schemes have been implemented by wire bonding, on p and on n-side, respectively. Capacitance and dissipation factor have been measured versus bias voltage and frequency. These data are being used to estimate the noise contribution of the detector and to choose the best z-side connection scheme in the SVT.