Mu3e Integration Run 2021

TL;DR

The paper reports on the 2021 integration run of the Mu3e experiment, detailing the data acquisition system and initial results from operating a detector slice at PSI, aiming to detect rare muon decays.

Contribution

It presents the first operational integration of Mu3e detector components and the DAQ system at PSI, demonstrating readiness for future data collection phases.

Findings

Successful operation of a detector slice at PSI

First data acquisition and filtering at high particle rates

Validation of DAQ system performance and data handling

Abstract

The Mu3e experiment at the Paul Scherrer Institute searches for the charged lepton flavor violating decay $\mu^+ \rightarrow e^+ e^+ e^-$. The experiment aims for an ultimate sensitivity of one in $10^{16}$ $\mu$ decays. The first phase of the experiment, currently under construction, will reach a branching ratio sensitivity of $2.5\times10^{-15}$ by observing $10^{8}$ $\mu$ decays per second over a year of data taking. The highly granular detector based on thin high-voltage monolithic active pixel sensors (HV-MAPS) and scintillating timing detectors will produce about 100 GB/s of data at these particle rates. The Field Programmable Gate Array (FPGA) based Mu3e Data Acquisition System will read out this data from the detector and reduce the event rate to 100 MB/s by selecting interesting events using a filter farm of graphics processing units. The paper presents the status of the data acquisition system (DAQ) and first results from the 2021 integration run, which for the first time operated a slice of the Mu3e detector at the $\pi$E5 muon beam line at the Paul Scherrer Institute (PSI).