Design and simulation of a cylindrical μRWELL inner tracker for the experiment at the Super Tau-Charm Facility

Abstract

The Super Tau-Charm Facility (STCF) is a future electron-positron collider operating in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5 × 1035 cm-2s-1. A high-performance detector is required for the STCF experiment to meet the STCF physics goals. A low-material cylindrical inner tracker based on the micro-resistive well detector (μRWELL) is proposed for the STCF experiment. In this paper, the design of the μRWELL inner tracker is presented. A good balance between material budget, structural strength, and detector performance is achieved in the design where the material budget of the μRWELL inner tracker is estimated to be 0.29% X/X0, a 40% reduction w.r.t. that of the cylindrical gas electron multiplier (CGEM) detector used at the KLOE experiment. The hit position of the detector is reconstructed using an algorithm combing the micro-time projection chamber (μ-TPC) method and the charge center-of-gravity method. The detector performance was studied in detail using simulation with Garfield and Geant4. With the optimum working gas of Ar: CO2 = 85:15, this detector can obtain a spatial resolution better than 100 μm and 400 μm in 1 T magnetic field in rφ and beamline direction, respectively. The simulated momentum resolution and vertex resolution of the whole STCF tracking system including the μRWELL inner tracker and a large drift chamber can meet the requirements for the STCF detector, benefiting from the optimized inner tracker design.