Elisa Riceputi

This paper presents the design and experimental characterization of a low-noise analog readout channel implemented in a commercial 65nm CMOS technology. The circuit targets the readout of large-area silicon-strip detectors for astroparticle physics tracker applications and is based on a charge-sensitive amplifier followed by a unipolar semi-Gaussian time-invariant filter. Dynamic signal compression is achieved by exploiting the nonlinear behavior of a dynamic-threshold MOS capacitor in the amplifier feedback network, providing a gain that decreases with increasing input signal and enabling a wide input dynamic range while maintaining high resolution at low deposited charge. The amplifier also incorporates an enhanced Krummenacher feedback network that, through an additional bulk-controlled device, compensates detector leakage currents up to 200 nA. The design criteria and circuit architecture are described, with emphasis on the dynamic-threshold capacitor and the improved charge restoration network. Experimental results are presented to validate and support the proposed design and architectural choices.

The General AntiParticle Spectrometer (GAPS) is a balloon-borne experiment designed to search for low-energy cosmic-ray antinuclei as a potential indirect signature of dark matter. Over the course of at least three long-duration flights over Antarctica, it will explore the sub-250 MeV/n energy range with sensitivity to antideuterons and antihelium, while also extending antiproton measurements below 100 MeV. The instrument features a tracker built from more than one thousand lithium-drifted silicon detectors, each read out by a dedicated custom integrated circuit. With the first flight scheduled for the austral summer of 2025, a new prototype chip, ANTARES4, has been developed using a commercial 65 nm complementary metal-oxide semiconductor process for use in the second flight. It integrates eight independent analog channels, each incorporating a low-noise charge-sensitive amplifier with dynamic signal compression, a CR–RC shaping stage with eight selectable peaking times, and on-chip calibration circuitry. The charge-sensitive amplifier uses metal-oxide semiconductor feedback elements with voltage-dependent capacitance to support the wide input energy range from 10 keV to 100 MeV. Four alternative feedback implementations are included to compare performance and design trade-offs. Leakage current compensation up to 200 nA per detector strip is provided by a Krummenacher current-feedback network. This paper presents the design and architecture of ANTARES4, highlighting the motivations, design drivers, and performance requirements that guided its development.

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.

This paper studies the effect of high levels of ionizing radiation on the analog parameters, with particular emphasis on the small signal and noise characteristics, of MOSFET devices belonging to a 28 nm bulk CMOS technology. The effects of total ionizing dose (TID) on drain leakage current, threshold voltage, transconductance, gate leakage current, intrinsic gain, and 1/f noise are studied. Post-irradiation annealing reverses the performance degradation of some analog parameters by neutralizing oxide-trapped charge. The results show the extreme radiation hardness of this technology node, proving its applicability in high energy physics experiments and photon science applications.