The extension of the BESIII experiment (IHEP, Beijing) until 2030 has triggered a program to
improve the accelerator and the detector. In particular, it is proposed to replace the current inner
drift chamber with a cylindrical GEM detector. The inner CGEM tracker consists of three coaxial
layers of triple GEM and is expected to restore efficiency, improve z-determination and secondary
vertex position reconstruction with a resolution of 130 μm in the xy-plane and better than 500 μm
along the beam direction. A special readout system was developed. The signals are processed
by TIGER, a custom 64-channel 110 nm ASIC that provides an analog charge readout via a fully
digital output to the GEM Read Out Card. The three layers were assembled in October 2023 and
a cosmic ray data collection campaign is underway to evaluate performance prior to installation
in BESIII. The general status of the CGEM-IT project will be presented, with a particular focus
on the first cosmic ray detection results.

