An ultra-light helium cooled pixel detector for the Mu3e experiment

• DOI: 10.48550/arxiv.2307.14803
• Publication Date: 2023-01-01
• Authors: Thomas Theodor Ru...; Heiko Augustin; David Maximilian ...; R. Kolb; Lukas Mandok
• Keywords: High Energy Physics - Experiment (hep-ex); Physics - Instrumentation and Detectors; 0103 physical sciences; FOS: Physical sciences; Instrumentation and Detectors (physics.ins-det); 7. Clean energy; 01 natural sciences; High Energy Physics - Experiment

The Mu3e experiment searches for the lepton flavour violating decay $\mu^+ \rightarrow e^+ e^- e^+$ with an ultimate aimed sensitivity of $1$ event in $10^{16}$ decays. To achieve this goal, must minimize material budget per tracking layer to $X/X_0\approx 0.1\,\%$ and use gaseous helium as coolant. pixel detector uses High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) which are thinned down $50\, \mu m$. Both cooling HV-MAPS a novelty particle detectors. Here, work on successfully tracker using is presented. thermal studies focus two inner layers, vertex detector, first operation functional thin cooled helium. approach, circulates under ambient pressure conditions gas temperature around $0\,{\deg}C$ miniature turbo compressor mass flow $2\,g/s$ allows operate below $70\,{\deg}C$ at heat densities up $350\,mW/cm^2$. Finally, performance data final used by Mu3e, MuPix11, These results demonstrate feasibility combined coolant ultra-thin exploring new frontiers flavor.