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Published June 2020 | metadata_only
Journal Article

Mu2e e.m. Calorimeter: Crystals and SiPMs Production Status


The Mu2e experiment at Fermilab will search for the charged lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus [1] , [2] . The Mu2e detector is comprised of a tracker, an electromagnetic calorimeter, and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities, a fast and online trigger filter while aiding the track reconstruction capabilities. The calorimeter requirements are to provide a large acceptance for 100-MeV electrons and reach: 1) a time resolution better than 0.5 ns at 100 MeV; 2) an energy resolution O(10%) at 100 MeV; and 3) a position resolution of about 1 cm. The calorimeter consists of two disks, each one made of 674 pure CsI crystals readout by two large-area 2×3 array of UV-extended silicon photomultipliers (Mu2e SiPMs) of 6×6 mm² dimensions. A large-scale prototype has been constructed with 51 preproduction crystals readout by 102 Mu2e SiPMs. It has been tested at the beam test facility in Frascati, demonstrating satisfying results compared to the Mu2e requirements. At the moment of writing, the crystals production phase is halfway through the work, while the SiPM production has been completed. An overview of the characterization tests is also reported, together with a description of the final calorimeter design.

Additional Information

© 2020 IEEE. Manuscript received February 13, 2020; accepted April 1, 2020. Date of publication April 16, 2020; date of current version June 19, 2020. This work was supported in part by the U.S. Department of Energy, in part by the Italian Istituto Nazionale di Fisica Nucleare, in part by the Science and Technology Facilities Council, U.K., in part by the Ministry of Education and Science of the Russian Federation, in part by the U.S. National Science Foundation, in part by the Thousand Talents Plan of China, in part by the Helmholtz Association of Germany, and in part by the EU Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant under Grant 690835. The authors are grateful for the vital contributions of the Fermilab staff and the technical staff of the participating institutions. In particular, they thank all the Laboratori Nazionali di Frascati (LNF) mechanical shop for the realization of the support and the beam test facility (BTF) staff for providing the beam time and helping them in getting a smooth running period. They express their warmest thanks to L. Foggetta for adjusting and tuning the beam to our detector needs. This document was prepared by members of the Mu2e Collaboration using the Resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract DE-AC02-07CH11359.

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August 19, 2023
August 19, 2023