• particle physics
• INFN
• Avalanche
• DIRAC
• DRAC
• transceiver
• optical fibers
• XCVR
• Libero
• Polarfire
• Microsemi
• FPGA
• TDAQ
• Fermilab
• Mu2e

The purpose of the Mu2e experiment at Fermi National Accelerator Laboratory (Fermilab) is the research for the neutrino-less coherent conversion of the muon into an electron, in the field of an aluminum nucleus. The observation of this physics process would unambiguously demonstrate the existence of physics beyond the Standard Model. Although in the past there's always been a huge amount of experimental research activity, all the previous researches for this process have given null results. The experimental technique employed by Mu2e experiment has been designed to improve the sensitivity by four orders of magnitude with respect to similar experiments.
Mu2e is a complex experimental apparatus composed by a high intensity pulsed muon beamline and several independent particle detectors; including a straw-tracker and a crystal-based electromagnetic calorimeter. The calorimeter has been designed and will be built by the collaboration among the Italian National Institute of Nuclear Physics (INFN), the California Institute of Technology (Caltech) and the Fermi National Accelerator Laboratory (FNAL or Fermilab).
The Mu2e Tracker will precisely measure momentum of charged particles that traverse it. This is critical to distinguish the well-known momentum of the signal electrons from background particles that have different momenta. The momentum measurement can be made because a charged particle will trace a helical path through the uniform magnetic field of the Detector Solenoid and the radius of this helix is directly proportional to its momentum. The Mu2e calorimeter is vitally important in reducing backgrounds. Its primary purpose is to provide a set of measurements that complement the information from the Tracker and enable us to reject backgrounds due to reconstruction errors and cosmic ray interactions not vetoed by the cosmic ray veto. For real tracks, activity in the Tracker and in the calorimeter will be correlated in time. The combination of these two timing measurements provides a time-of-flight system that could be capable of providing particle identification information.
Both Tracker and calorimeter are challenging detector, operating in a hostile environment of 1 T magnetic field, a harsh radiation level and $10^-4$ Torr vacuum. Moreover, the detector will be installed inside an evacuated cryostat and will be accessible for maintenance only for an extremely limited number of weeks per year.
Operation in vacuum has an important impact on the detector design: all the components have to be vacuum-compatible and a dedicated cooling system is necessary to maintain electronic components within a range of temperature suited for safe long-term operation. Electronics needs to take into account also the expected high radiation levels, using radiation-hard components.
The goal of this thesis is the analysis, the design and the implementation of the detector electronic responsible for the experiment data acquisition. The Mu2e Trigger and Data Acquisition (TDAQ) subsystem provides necessary components for the collection of digitized data from the Tracker and the Calorimeter, and delivery of that data to online and offline processing for analysis. It is also responsible for detector synchronization, control, monitoring, and operator interfaces. It provides a timing and control network for precise synchronization and control of the data sources and readout, along with a Detector Control System (DCS) for operational control and monitoring of all Mu2e subsystems.
It is based on a “streaming” readout: his means that Tracker and Calorimeter detector data is digitized, zero-suppressed in front-end electronics, and then transmitted off the detector to the TDAQ system. The Mu2e TDAQ architecture is further simplified by the integration of all off-detector components in a “TDAQ Server” which functions as a centralized controller, data collector and data processor.
Most of the work done on this thesis is about firmware development on the boards responsible for data collection and control operation: the DRAC for the Tracker and the DIRAC for the Calorimeter. Three was the main goals: first create a functioning firmware for the DRAC at Fermilab, where the environment is set. At Fermilab is available a Test Stand with all the main parts that will compose the experiment. Second, reproduce the Fermilab Test Stand at INFN in Pisa to have an environment to test the DIRAC. The last one, validate DIRAC hardware with a modified version of the DRAC firmware. An additional task has been the reproduction of DIRAC hardware validation at the Test Stand at INFN, reaching the same developing point both in Fermilab and at INFN. This thesis set the groundwork to the future development of the DIRAC firmware.
Both DRAC, the Tracker digitizer and readout controller board, and DIRAC, the Calorimeter readout controller board, mount a Microsemi PolarFire FPGA MPF300TS-1FG1152. Microsemi offers the Microsemi Libero System-on-Chip (SoC) design suite comprehensive of development tools for designing in VHDL. The suite integrates industry standard Synopsys Synplify Pro synthesis and Mentor Graphics ModelSim simulation with constraints management, debug capabilities, and secure production programming support. Challenging step about the firmware development has been the data storage, the management of data flow, the optical interface and the board synchronization. Main purpose of both DRAC and DIRAC is store on a DDR3 data retrieved from the event observed by the detectors and send that data to the TDAQ. The two boards interface the TDAQ via a two 2.5 Gbps fibers connected to a Data Transfer Controller, so, part of the development was about the DDR3 control and part was about optical link management via a transceiver structure. The most demanding of this work has been the implementation of communication between the Read Out Controller and the TDAQ and the synchronization of the boards.
Structure of this document goes from general to specific. First is presented the experiment, goals and facility, then the TDAQ, environment within which is developed the work of this thesis. Two chapter are dedicated to the development boards, DRAC and DIRAC: characterization and work done for each. Last chapter is the most specific about the firmware analysis and development. Last part of this thesis takes into account of future development.