Front-end Readout ASIC Design for Ultra-fast Sensors Used in Muon Detectors

by Alexander Elsenhans

Thursday Nov 26, 2026, 2:00 PM → 3:00 PM Europe/Berlin

Seminarraum EG (IPE)

Alexander Elsenhans will present his PhD defense talk. The final presentation of his research will take place on December 10.

Abstract:

This work presents the design, implementation, and characterization of front-end ASICs for ultra-fast photon detection in muon detector systems based on scintillator-wavelength shifting (WLS) fiber technology. The primary objective is to improve the spatial and temporal resolution of muon detection by leveraging advanced CMOS single-photon avalanche diode (SPAD) arrays with integrated time-to-digital converters (TDCs). The physical principles of muon detection and SPAD operation, as well as the state of the art in muon detectors and CMOS SPAD arrays will be reviewed. Particular emphasis is placed on SPAD key parameters and readout architectures, with a comparison of analog silicon photomultipliers (SiPMs) and digital SPAD-based solutions.

 

Two ASICs have been developed:

• The first, ANDESPix, is a fully integrated SPAD array implemented in a 110 nm CMOS process, comprising 1980 pixels with one TDC per pixel. Each pixel incorporates two SPADs with passive quenching and digital signal generation. An SRAM-based delay-line TDC architecture enables high integration density and continuous operation with zero-suppressed readout. Experimental characterization demonstrates effective fine-TDC bin widths of 100 ps to 150 ps. For pixels operating within locally linear regions of the TDC transfer characteristic, an instrument response function (IRF) of approximately 270 ps was achieved.

• The second ASIC, PicoParticleCore, implemented in a 16 nm FinFET technology, explores compact high-resolution TDC architectures based on gated ring oscillators, achieving time resolutions in the picosecond range.

 

Photon pulse measurements in scintillator-WLS systems using analog SiPMs reveal characteristic features such as prompt signals, afterpulsing, and fiber-end reflections, providing insight for optimizing digital readout architectures.

 

The results demonstrate that SPAD arrays with per-pixel TDCs enable detailed time-resolved photon measurements and provide a viable approach for future muon detector readout systems, forming a basis for further developments including hybrid 3D-integrated architectures.