Design and performance of the SLD vertex detector: a 307 Mpixel tracking system

TLDR

The paper presents the design, construction, and initial operation of SLD’s upgraded vertex detector, a 307‑megapixel system of 96 two‑dimensional CCDs. Each 4‑µm‑precision pixel serves as an independent particle‑detector element arranged in three concentric cylinders around the e⁺e⁻ collision point, enabling high‑speed readout and low‑mass, low‑temperature operation to distinguish displaced‑vertex tracks from primary tracks. The experience gained demonstrates that such a low‑mass, high‑speed CCD array can be successfully built and operated, offering guidance for future large‑scale CCD or active‑pixel detector projects.

Abstract

This paper describes the design, construction, and initial operation of SLD's upgraded vertex detector which comprises 96 two-dimensional charge-coupled devices (CCDs) with a total of 307 Mpixel. Each pixel functions as an independent particle detecting element, providing space point measurements of charged particle tracks with a typical precision of 4 μm in each co-ordinate. The CCDs are arranged in three concentric cylinders just outside the beam-pipe which surrounds the e+e− collision point of the SLAC Linear Collider (SLC). The detector is a powerful tool for distinguishing displaced vertex tracks, produced by decay in flight of heavy flavour hadrons or tau leptons, from tracks produced at the primary event vertex. The requirements for this detector include a very low mass structure (to minimize multiple scattering) both for mechanical support and to provide signal paths for the CCDs; operation at low temperature with a high degree of mechanical stability; and high speed CCD readout, signal processing, and data sparsification. The lessons learned in achieving these goals should be useful for the construction of large arrays of CCDs or active pixel devices in the future in a number of areas of science and technology.