Instruments for calibration and monitoring of the LHCb Muon Detector

The subject of this Ph. D. thesis is the study and the development of the instruments needed to monitor and calibrate the Muon Detector of the LHCb (Large Hadron Collider beauty) experiment. LHCb is currently under installation at the CERN Large Hadron Collider (LHC) and will start to take data during 2007. The experiment will study B mesons decays to achieve a profound understanding of favour physics in the Standard Model framework and to search signs of new physics beyond. Muons can be found in the final states of many B-decays which are sensitive to CP violation. The Muon Detector has the crucial role to identify the muon particles generated by the b-hadron decays through a measurement of their transverse momentum, already at the first trigger level (Level-0). A 95% effciency in events selection is required for the Muon Trigger, which operates at the Level-0. 1380 detectors are used to equip the whole Muon System and the corresponding 122,112 readout channels must be time aligned and monitored with a resolution of a few ns to assure the correct Muon Trigger selection. In order to satisfy these requirements, it is necessary to distinguish the time distributions of muons generated by B-decays from the background and center them inside the bunch crossing period. Moreover, the selected events must be unambiguously associated to the bunch crossing which generated the detected muons. Before synchronization, signals generated to the same bunch crossing and coming from different readout channels will have different absolute delays with respect to the interaction time. The electronic instruments designed to time align and to monitor each Muon Detector readout channel are two Application Specific Integrated Circuits (ASIC), called DIALOG (DIagnostic time Adjustment and LOGics) and SYNC, developed in CMOS IBM 0.25 um technology. The DIALOG chips are placed on the detectors, at the beginning of the electronic chains used to collect and to send the channel information to the Muon Trigger. The SYNC chips are placed at the end of the chains. In the Muon System there are 7632 DIALOG and 3552 SYNC devices. DIALOG and SYNC are VLSI (Very Large Scale Integration) circuits and were designed in Cagliari by the LHCb group. My research activity was at first focused on the design and on the simulation of the two ASICs. DIALOG is a mixed-signal circuit constituted by analog, digital and mixed blocks. SYNC is a synchronous digital circuit working at 40 MHz. After chip submissions, a semi-automatic test bench called DIALOG Test System (DTS) was developed to characterize and validate all DIALOG prototype characteristics. About 500 DIALOG chips were characterized in full detail by means of the DTS, allowing the definition of the proper sorting intervals needed to perform the validation of the about 12,000 DIALOG mass production chips. The last part of my work was to study the feasibility of the Muon System time alignment, using the realized instruments during the first phase of LHCb data taking. The data tacking time required to perform the alignment was investigated.