The Mu3e exeriment aims to find or exclude the lepton-flavour violating decay μ+→e+e+e− with an ultimate sensitivity of 1 in 1016 decays. For thie we use the most intense Muon beam in the world at the Paul Scherrer Institute in Villigen Switzerland. The detector combines ultra-light High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) with scintillating fibres and tiles for very precise timing measurements.

Mu3e produces about 1 TBit/s of data, which we all read out of the detector using a network of FPGAs and fast optical links then and analyze for interesting events using massively parallel computing on graphics processing units. This data acquisition and filtering system is contributed by our group.

The Mainz group also designed and built the detector powering and safety system, including challenging high-power DC/DC converters.

Mu3e is completing the first phase of the detector and will take data in 2026 and 2027.

The complete data stream from the Mu3e detector is sent to the filter farm, where we use GPUs to reconstruct tracks and decay vertices. If the event looks like the μ+→e+e+e− signal, we save the raw data.

Our group is building the data acquisition and filter farm for the Mu3e experiment. This system transports up to a 1 TBit/s of data out

The Mu3e detetcor uses two different application specific integration circuits (ASICs), the MuPix pixel chips and the MuTrig time-to-digital converters for the scintillating detectors. Both output digitized and zero-suppressed data streams as 1.25 GBit/s differential data streams. These streams are collected on 114 front-end boards located inside the decteor magnet. There the data are sorted and sent out of the detector using fast optical links.

The system is also used for monitoring and configuring the detector ASICs; for all of this we have developed custom FPGA firmware.

The Mu3e detector – in particular the pixel detectors – need Kilowatts of power at 2-3 Volts. We designed custom high-efficiency DC/DC converters capable of operating inside the Mu3e magnet to provide the power starting from a 24 Volt input.

We also designed a multi-stage interlock system, that automatically turns off power if detector cooling is lost.

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