A high-performance silicon tracker for the Compressed Baryonic Matter experiment at FAIR

Abstract

The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion experiment planned at GSI's future international Facility for Antiproton and Ion Research (FAIR). CBM will study strongly interacting matter at high baryon densities where the QCD phase diagram is poorly known. The experiment applies a detector concept new to heavy-ion physics: All charged particles as well as secondary vertices from heavy-flavor decays are exclusively reconstructed in a high-performance silicon tracking system. It will be installed in a magnetic dipole field between the target and further detection systems for particle identification and calorimetry. High track densities and high collision rates require the application of most advanced silicon detectors. The technological challenges include high position resolution in thinnest possible pixel and microstrip sensors, combined with extreme radiation hardness, fast self-triggered readout and ultra low-mass mechanical supports. The article outlines the physics and detector concept of CBM and discusses the performance requirements of the silicon tracker and the beginning R&D.