Characterising CE-65 monolithic sensors towards FCC-ee vertex detectors

The beginning of particle physics can be traced back to 1895 when, in a cathode ray tube experiment, Röntgen accidentally discovered X-rays. Since then, many new particles have been discovered, some before and others after they were theoretically explained. In the 1960s, with the development of the first accelerator machines accelerating particles to probe higher energies, many new particles were found in a short time, and physicists sought to bring order to this “particle zoo”, as this mass of new particles and the resulting difficulties in finding their inner structure, was called. A theoretical model was required to organise the mass of composite particles found with these first accelerators. This model includes the fundamental building blocks of hadrons (quarks) and became the Standard Model (SM) of particle physics. It is one of the most precise and, at the same time, elegant theoretical descriptions. It includes only two different kinds of particles - fermions, of which matter consists, and bosons, the fundamental force carrier particles - and explains three of the four fundamental forces: The weak force, the strong force and the electromagnetic force, only leaving out the gravitational force. The SM was completed in 2012 by the experimental finding of the last of its predicted particles, the Higgs boson, at the Large Hadron Collider (LHC) at CERN.                                                                                                                                     The fermions in the SM are grouped into three “generations” of particles, which are physically similar, although the particles differ in their masses. In this context, the SM’s first unanswered question can be posed: why are there three generations and not four or two? Furthermore, the Higgs field gives mass to the massive particles of the SM through the Higgs mechanism. But why are the masses as they are? Why is the coupling of the Higgs particle different for each particle? Might the Higgs particle be composite?
For these and many more open questions concerning the newest particle, it is important to do further precision measurements on the Higgs boson and trace the limits of the SM. Especially for these measurements, it is necessary to probe the fundamental laws of nature using higher energies and greater precision. Thus, the particle physics community is evaluating different concepts for the successor of the LHC, aiming to push the energy and intensity frontier. The most prominent successor of the LHC is the proposed Future Circular Collider (FCC). In its first phase, the FCC-ee will accelerate electrons and their antiparticles, the positrons, and collide them to produce very clean collisions for precision measurements of the properties of the SM. It is designed to enable such precision measurements in connection with, for example, the Higgs boson, the top quark, the electroweak sector, and flavour physics. Especially for flavour physics at the Z pole, it will be important to have an excellent reconstruction of the primary, secondary and tertiary vertices, as hadrons containing heavy quarks typically have short lifetimes and need to be reconstructed for these measurements. A precise vertex reconstruction necessitates high-precision, light inner tracking layers; the vertex detector. The investigation of this detector and its sensor candidates with regard to the FCC-ee requirements is the central point of this thesis. In the scope of this work, sensor prototypes are characterised following the requirements of vertex detectors at future electron-positron colliders like the FCC-ee. This includes the question of whether a resolution of 3 µm can be reached in 65 nm CMOS Imaging Process (CIS) technology. This characterisation aims to compare different chip variants to guide the development of the next generation of sensors that eventually would instrument FCC-ee vertex detectors.