The Mu2e experiment at Fermilab is designed to search for charged lepton flavor violation (CLFV) by looking for the rare, neutrinoless conversion of a muon into an electron in the field of a nucleus. The goal of the experiment is to reach a sensitivity four orders of magnitude beyond the current limit, by means of a sophisticated system of superconducting solenoids and high-precision detectors. The solenoid system comprises production, transport, and detector solenoids. Inside the production solenoid, a proton beam hits a target, producing pions that subsequently decay into muons. These particles are filtered through the transport solenoid, which selects only negatively charged muons. The resulting beam is then stopped in a muon stopping target housed within the detector solenoid. Downstream of the stopping target, two detectors, a straw tracker and a crystal calorimeter, measure the momentum and energy of the outgoing conversion electrons. To reject possible background events, a cosmic ray veto system surrounds the last section of the transport solenoid and the entire detector solenoid. This paper describes the current status of the experiment, from the proton beam to the solenoid and detector systems, and discusses the milestones leading up to the initial data collection scheduled to begin in 2027.

The Fermilab report number for this document is: FERMILAB-CONF-26-0360-PPD.