Development and operation of the CGEM Inner Tracker for the BESIII experiment

TL;DR

This paper discusses the development, construction, and testing of the CGEM Inner Tracker upgrade for the BESIII experiment, including electronics, data acquisition, and test results from cosmic rays and CERN test beams.

Contribution

It introduces the innovative CGEM-IT system with new electronics and data acquisition methods, and reports on its successful testing and operation status.

Findings

Successful operation of two layers since 2020

Effective cosmic ray and test beam data collection

Electronics and readout system meet design specifications

Abstract

The extension of data acquisition for the BEijing Spectrometer (BESIII) experiment until at least 2030 has resulted in upgrades to both the accelerator and the detector. An innovative Cylindrical Gas Electron Multiplier (CGEM) is under construction to upgrade the inner tracker, which is suffering from aging. The CGEM Inner Tracker (CGEM -IT) was designed to restore efficiency and enhance the reconstruction of the secondary vertexes position. Reconstruction in the magnetic field of 1 T requires an analog readout and an electronic contribution to the time resolution better than 5 ns. The entire system consists of about 10,000 electronic channels and must maintain a peak rate of 14 kHz/strip of signal hits for the innermost layer of the CGEM-IT. The CGEM readout system is based on the innovative TIGER ASIC, which is manufactured using 110 nm CMOS technology. A special readout chain consisting of GEM Read Out Cards (GEMROC) was developed for data acquisition. Two of three layers, equipped with the final electronics, have been operating in Beijing since January 2020 collecting cosmic ray data in a test facility, remotely controlled by the Italian group due to the pandemic situation. Since it was not possible to perform further tests on the cylindrical detector, in July 2021, a test beam was conducted at CERN with the final electronics configuration on a small prototype consisting of four triple-GEM planar detectors. In this presentation, the general status of the project CGEM-IT will be presented, with particular emphasis on the results of the test beam data collection.