The Mu3e experiment is searching for the charged lepton flavour violating decay\break μ+→e+e−e+, aiming for an ultimate sensitivity of one in 1016 decays. In an environment of up to 109 muon decays ...per second the detector needs to provide precise vertex, time and momentum information to suppress accidental and physics background. The detector consists of cylindrical layers of 50μm thin High Voltage Monolithic Active Pixel Sensors (HV-MAPS) placed in a 1T magnetic field. The measurement of the trajectories of the decay particles allows for a precise vertex and momentum reconstruction. Additional layers of fast scintillating fibre and tile detectors provide sub-nanosecond time resolution. The MuPix8 chip is the first large scale prototype, proving the scalability of the HV-MAPS technology. It is produced in the AMS aH18 180nm HV-CMOS process. It consists of three sub-matrices, each providing an untriggered datastream of more than 10MHits/s. The latest results from laboratory and testbeam characterisation are presented, showing an excellent performance with efficiencies >99.6% and a time resolution better than 10ns achieved with time walk correction.
Monolithic active pixel sensors (MAPS) based on commercial high-voltage CMOS processes are an exciting technology that is considered as an option for the ATLAS Inner Tracker upgrade. Particles are ...detected using deep n-wells on a p-type substrate as sensor diodes with the depleted region extending into the silicon bulk. With readout electronics and sensor integrated on the same device, the detector complexity and the material budget are greatly reduced. The ATLASPix1 pixel sensor prototype is a large-scale MAPS prototype that implements the full readout chain on a single physical chip. It features a large in-pixel sensor electrode and is produced using the ams aH18 high voltage technology. Three pixel matrices with different readout architectures, triggered and untriggered, and pixel designs are implemented. We show the performance of one of the pixel matrix variants for samples irradiated up to 1015 1MeV meq/cm2.
High Voltage Monolithic Active Pixel Sensors (HV-MAPS) are based on a commercial High Voltage CMOS process and collect charge by drift inside a reversely biased diode. HV-MAPS represent a promising ...technology for future pixel tracking detectors. Two recent developments are presented. The MuPix has a continuous readout and is being developed for the Mu3e experiment whereas the ATLASPix is being developed for LHC applications with a triggered readout. Both variants have a fully monolithic design including state machines, clock circuitries and serial drivers. Several prototypes and design variants were characterised in the lab and in testbeam campaigns to measure efficiencies, noise, time resolution and radiation tolerance. Results from recent MuPix and ATLASPix prototypes are presented and prospects for future improvements are discussed.
The upcoming Mu3e experiment will search for the charged lepton flavour violating decay of a muon at rest into three electrons. The maximal energy of the electrons is 53 MeV, hence a low material ...budget is a key performance requirement for the tracking detector. In this paper we summarize our approach to meet the requirement of about 0.1 % of a radiation length per pixel detector layer. This includes the choice of thinned active monolithic pixel sensors in HV-CMOS technology, ultra-thin flexible printed circuits, and helium gas cooling.
The Mu3e experiment aims to find or exclude the lepton flavour violating decay \(\mu \rightarrow eee\) at branching fractions above \(10^{-16}\). A first phase of the experiment using an existing ...beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of \(2\cdot 10^{-15}\). We present an overview of all aspects of the technical design and expected performance of the phase~I Mu3e detector. The high rate of up to \(10^{8}\) muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.
The Mu3e experiment is searching for the charged lepton flavour violating decay \( \mu^+\rightarrow e^+ e^- e^+ \), aiming for an ultimate sensitivity of one in \(10^{16}\) decays. In an environment ...of up to \(10^9\) muon decays per second the detector needs to provide precise vertex, time and momentum information to suppress accidental and physics background. The detector consists of cylindrical layers of \(50\, \mu\text{m}\) thin High Voltage Monolithic Active Pixel Sensors (HV-MAPS) placed in a \(1\,\text{T}\) magnetic field. The measurement of the trajectories of the decay particles allows for a precise vertex and momentum reconstruction. Additional layers of fast scintillating fibre and tile detectors provide sub-nanosecond time resolution. The MuPix8 chip is the first large scale prototype, proving the scalability of the HV-MAPS technology. It is produced in the AMS aH18 \(180\, \text{nm}\) HV-CMOS process. It consists of three sub-matrices, each providing an untriggered datastream of more than \(10\,\text{MHits}/\text{s}\). The latest results from laboratory and testbeam characterisation are presented, showing an excellent performance with efficiencies \(>99.6\,\text{\%}\) and a time resolution better than \(10\, \text{ns}\) achieved with time walk correction.
PDF