Study of the Tracking Method and Expected Performance of the Silicon Pixel Inner Tracker Applied in BESIII

TL;DR

This paper investigates the use of CMOS pixel sensors as an inner tracker for BESIII, demonstrating through simulation that it significantly improves tracking performance and addresses aging issues of the existing detector.

Contribution

It presents a Monte Carlo simulation study of a silicon pixel inner tracker for BESIII, highlighting its advantages over the aging drift chamber.

Findings

Improved momentum and vertex resolution with silicon pixel tracker

Enhanced tracking efficiency due to better spatial resolution

Significant performance gains demonstrated through simulation

Abstract

The inner drift chamber of the BESIII is encountering serious aging problem after five year's running. For the first layer, the decrease in gas gain is about 26% from 2009 to 2013. The upgrade of the inner tracking detector has become an urgent problem for the BESIII experiment. An inner tracker using CMOS pixel sensors is an important candidate because of its great advantages on spatial resolution and radiation hardness. In order to carry out a Monte Carlo study on the expected performance, a Geant4-based full simulation for the silicon pixel detector has been implemented. The tracking method combining the silicon pixel inner tracker and outer drift chamber has been studied and a preliminary reconstruction software was developed. The Monte Carlo study shows that the performances including momentum resolution, vertex resolution and the tracking efficiency are significantly improved due to the good spatial resolution and moderate material budget of the silicon pixel detector.