Development of a DAQ system for depleted monolithic active pixel sensors

Abstract

Silicon sensors are used today in almost all experiments in particle physics. Since they can be easily segmented using standard photo-lithographic techniques, they can achieve excellent position resolution and play a key role in measuring primary and secondary vertices and tracking of charged particles. Up to now, the sensors were read out by dedicated front-end electronic chips connected via bump- or wire-bonding techniques, which is limiting their performance because of a rather high material budget and complicated and expensive assembling procedures. After years of research and development, Depleted Monolithic Active Pixel Sensors(DMAPS) manufactured by Complementary Metal-Oxide-Semiconductor (CMOS) technologies now allow a combination of the charge-sensitive volume and the active readout electronics into one device. This technology is particularly suitable for applications that require low material budget and excellent position resolution, such as those required for electron machines such as Belle II upgrades or the Future Circular Collider-ee (FCC-ee). However, more significant improvements in their radiation tolerance are needed to meet the needs of hadron accelerator experiments such as the high luminosity Large Hadron Collider (LHC) or theFCC-hh.In order to further push the technology in this promising field, DMAPS are being developed within the RD50 collaboration using the LFoundry 150 nm CMOS process. Within this thesis I characterized and studied the second prototype RD50-MPW2. The active matrix of this chip consists of 8×8 pixels, but the pixels can only be read out one after another due to the analogue front end. I established the Data Acquisition (DAQ) system to operate and read out this detector by embedding the chip in hardware and software framework, called Control and Readout Inner Tracking Board (CaRIBOu) and Peary, respectively. The CaRIBOu framework is used and tested in stand-alone operation with a radioactive 90-Sr source in the laboratory and also in a proton beam at the MedAustronsynchrotron embedded into an EUDAQ2 environment. Within these measurements, I determined the general performance of the chip and compared an unirradiated chip with chips irradiated up to a 1 MeV neutron-equivalent fluence of 10^14 neq /cm2.