出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：ALICE (A Large Ion Collider Experiment) is a general purpose experiment optimized for the study of heavy-ion collisions at the CERN LHC. The physics programme includes protonproton collisions for reference data and also for genuine physics topics for which ALICE is complementary to the other LHC experiments [1]. The ALICE Inner Tracking System (ITS) is the innermost tracking detector of ALICE and therefore it plays a key role in tracking and vertexing capabilities. The ITS consists of three coaxial subsystems, surrounding the beam pipe, each one comprising two layers based on different silicon technologies: the Silicon Pixel Detector (SPD), the Silicon Drift Detector (SDD) and the double-sided Silicon Strip Detector (SSD), innermost to outermost respectively. The number, position, granularity and technologies of the layers were optimized for efficient track finding and high impact-parameter resolution in the severe high-multiplicity environment expected for the central Pb-Pb collisions at LHC energy [2]. After two years of operation with p-p and Pb-Pb collisions, the ITS has demonstrated its tracking and vertexing capabilities, which are in excellent agreement with the design values. Since the ITS project was frozen, almost 10 years ago, the frontier silicon detector technologies have made a substantial progress and therefore nowadays a detector upgrade based on the currently ongoing developments may allow a substantial enhancement of the ALICE physics capabilities. In particular, the ITS upgrade will improve the tracking performance for heavyflavour detection, where the impact parameter resolution to the primary vertex position plays a crucial role. After a brief introduction on the performance of the present ITS, this contribution will focus on the ongoing studies for an upgrade of the ITS.
