Analisi di un sistema di riferimento temporale per la misura di tempi di volo di particelle cariche a LHC

This thesis is the result of an internship conducted in 2016 at CERN. The activity was carried out at the laboratories of the TOTEM experiment and, in particular, on CMS joint project equipment, called CMS-TOTEM Precision Proton Spectrometer (CT-PPS). The collaboration envisages reconstructing the quadruple-pulse of protons that survive collisions within LHC, to study Central Exclusive Production (CEP) processes. The accelerator magnetic fields deviate from the beam orbit the protons that lost a small fraction of their initial pulse in the collisions. Protons interacting by inelastic scattering ("central diffraction") are then detected by CT-PPS with detectors at a distance of ~ 220m from both sides of the interaction point, to reconstruct their trajectories. The process described is by means of a multiple exchange of gluons or photons, with quantum numbers exchanged equivalent to those of the vacuum. CT-PPS is active during LHC high-luminosity runs, so the working conditions of the detectors result hard. In fact, the measured protons flux at the detector stations is ~ 10^15 cm^-2 for an integrated luminosity of 100 fb^-1. For this reason, solid state detectors capable to offer "radiation hardness" have been developed. High luminosity runs are also characterized by the marked presence of the "pile-up" phenomenon, that is the occurrence of more than one proton-proton interaction during the same bunch-crossing (expected ~ 30-50). However tracking detectors, due to their distance from the interaction point, cannot separate the various primary vertices and reconstruct only central diffraction events. For this reason, protons time of flight detectors were realized ("4D-Reconstruction"). The difference between the arrival time of the particles at the detectors is proportional to the z-coordinate of their primary vertex. The first prototypes made for CT-PPS are diamond detectors with a timing resolution of less than 100 ps. The new "boards", still under test, show a double layer of diamonds and a resolution of the order of 50 ps. Recently, the collaboration has also developed silicon sensors (UFSD), which seem to have a better timing resolution than that achieved by the other detectors described. Time of Flight detectors require a reference timing system characterized by maximum precision and stability, namely a clock signal characterized by a jitter of less than 5 ps. The work presented in this thesis deals with the analysis I have made on TOTEM's clock distribution system. Particular attention has been given to the study of the measurement parameters of a Vector Network Analyzer (VNA), a tool needed to obtain the phase delay of the clock along a cable. This work was accompanied by the creation of an XML configuration file for the remote control of the VNA and of a C++ script for data analysis. Thanks to the studies made, it was possible to acquire and analyze phase delay of a periodic signal along coaxial cables and short optical fibres. In conclusion, the working point of a MachZender Modulator was studied.