X-ray and Particle Detection with the Si(Li) Tracker Module of the GAPS Experiment

This work describes the architecture and the experimental results from the characterization of the lithium-drifted silicon (Si(Li)) detector module, which constitutes the building block of the tracker in the General Antiparticle Spectrometer (GAPS) experiment to search for dark matter. The instrument is designed for the identification of low-energy cosmic antinuclei (antiprotons, antideuterons and antihelium) to be performed during an Antarctic long-duration balloon flight scheduled for late 2025. The GAPS Si(Li) tracker, that is the core of the instrument, is the assembly of 252 modules, each comprised of four Si(Li) detectors and a full custom integrated circuit designed for detector readout and produced in a commercial 180 nm planar CMOS technology. A general overview of the detector module architecture and its components is provided, together with a description of the test setup and the experimental results obtained from the characterization of the low-noise analog readout channel. In order to verify the effective operation of the entire module, results concerning the detection of X-rays from a 241Am source and cosmic muons are also provided.