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Published August 2018 | public
Journal Article

Design and Status of the Mu2e Crystal Calorimeter

Abstract

The Mu2e experiment at Fermilab searches for the charged-lepton flavor violating (CLFV) conversion of a negative muon into an electron in the field of an aluminum nucleus, with a distinctive signature of a monoenergetic electron of energy slightly below the muon rest mass (104.967 MeV). The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. Any observation of a CLFV signal will be a clear indication of new physics. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter, and an external veto for cosmic rays surrounding the solenoid. The calorimeter plays an important role in providing particle identification capabilities, a fast online trigger filter, a seed for track reconstruction while working in vacuum, in the presence of 1-T axial magnetic field and in a harsh radiation environment. The calorimeter requirements are to provide a large acceptance for 100-MeV electrons and reach at these energies: 1) a time resolution better than 0.5 ns; 2) an energy resolution <10%; and 3) a position resolution of 1 cm. The calorimeter design consists of two disks, each one made of 674-undoped cesium iodine crystals read by two large area arrays of UV-extended silicon photomultipliers (SiPMs). We report here the construction and the test of the Module-0 prototype. The Module-0 has been exposed to an electron beam in the energy range around 100 MeV at the Beam Test Facility in Frascati. Preliminary results of timing and energy resolution at normal incidence are shown. A discussion of the technical aspects of the calorimeter engineering is also reported in this paper.

Additional Information

© 2018 IEEE. Manuscript received December 31, 2017; accepted January 3, 2018. Date of publication January 8, 2018; date of current version August 15, 2018. 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 through the Marie Sklodowska-Curie Agreement under Grant 690835. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023