The MuPix System-on-Chip for the Mu3e Experiment

TL;DR

The paper presents the MuPix7 HV-MAPS prototype, a silicon pixel sensor with integrated electronics designed for precise vertex and momentum measurements in the Mu3e experiment, achieving over 99% efficiency in high-rate tests.

Contribution

Introduction of the MuPix7 HV-MAPS prototype with integrated digital readout and high-speed serialization for the Mu3e experiment.

Findings

MuPix7 achieves ≥99% efficiency in high-rate tests.

Integrates pixel sensor, analog electronics, and digital readout in a single chip.

Supports streaming readout at 1.25 Gbit/s.

Abstract

Mu3e is a novel experiment searching for charged lepton flavor violation in the rare decay $\mu^+ \rightarrow e^+e^-e^+$. Decay vertex position, decay time and particle momenta have to be precisely measured in order to reject both accidental and physics background. A silicon pixel tracker based on $50\,\mu$m thin high voltage monolithic active pixel sensors (HV-MAPS) in a 1 T solenoidal magnetic field provides precise vertex and momentum information. The MuPix chip combines pixel sensor cells with integrated analog electronics and a periphery with a complete digital readout. The MuPix7 is the first HV-MAPS prototype implementing all functionalities of the final sensor including a readout state machine and high speed serialization with 1.25 Gbit/s data output, allowing for a streaming readout in parallel to the data taking. The observed efficiency of the MuPix7 chip including the full readout system is $\geq99\%$ in a high rate test beam.