• Ansys
• conduction
• contact
• convection
• crystal
• csi
• experimental
• Fermilab
• fluidynamics
• heat
• infn
• measurement
• Mu2e
• peek
• polymer
• radiation
• resistance
• thermal
• vacuum

The purpose of the Mu2e experiment at Fermi National Accelerator Laboratory (Fermilab) is the search of the neutrinoless coherent conversion of the muon into electron in the electric field of an aluminium nucleus. The discovery of this physics process would unambiguously demonstrate the existence of Physics beyond the Standard Model.
The experimental technique employed by Mu2e has been designed to improve the sensitivity of four orders of magnitude with respect to previous experiments which have pursued similar searches.
Mu2e is a complex experimental apparatus composed of several independent detectors, including a straw-tracker and a crystal-based electromagnetic calorimeter.
The calorimeter has been designed and will be constructed by a collaboration among the Istituto Nazionale di Fisica Nucleare (INFN), the California Institute of Technology (CalTech) and Fermilab (FNAL). The calorimeter has the fundamental function to measure the electrons energy, time and position of impact. It is a challenging detector, designed to operate in a hostile environment: a large magnetic field, harsh radiation level and vacuum. Moreover, the detector will be accessible for maintenance only for an extremely limited number of weeks in one year since it will be installed inside an evacuated cryostat. Operation in vacuum has an immediate consequence on the electronics operation: a dedicated cooling system based is required. The high radiation level requires the use of radiation hard electronic components, which show an increase of power dissipation with the absorbed dose. All these possible effects have to be taken into account in the cooling design.
I have worked on my Master Thesis between June and November 2017. I have worked at the INFN Department of Pisa on the design of the calorimeter cooling system. The system is composed of two main subsystems, the first one dedicated to the front end electronics, the second one to the DAQ electronics. The front end and DAQ electronics systems are located in different regions of the detectors. I have performed the thermo-fluid dynamic analysis of the front end cooling system, the thermal simulations and validation tests.
Chapter 1 reports a description of the Mu2e experiment: the physics motivation, Fermilab accelerator chain (which provides the necessary muon beam), experimental apparatus and techniques;
Chapter 2 contains a detailed description of the Mu2e electromagnetic calorimeter and of its subsystems and components. Technical specifications, mechanics, electronics and cooling descriptions are briefly summarized;
Chapter 3 describes the thermo-fluid dynamic analysis that I have performed, including the assumptions and the results;
Chapter 4 reports the description of the FEM analysis of the "front end unit", which is composed of one cesium iodide (CsI) crystal and the associated front end electronics; this analysis has allowed to estimate the temperature field in different configurations and choose the best one in terms of cost, fabrication technique and thermal behaviour;
Chapter 5 describes my experimental activity. I have designed a setup and performed the necessary tests to validate the analytic model and simulation;
Chapter 6 reports a description of the challenging fabrication process of the backplate which will support the front end electronics and the associated cooling circuit;
Chapter 7 reports the conclusions and the future developments.