2025/01/09 by Ricci, Alessandro Maria
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Instrumentation and Detectors (physics.ins-det)
paper · doi:10.48550/arxiv.2501.05492
The Mu2e experiment, under construction at Fermilab, will search for the neutrino-less coherent μ-N→ e-N conversion in the field of a 27Al nucleus. Such a process violates lepton flavor conservation. About 60% of muons stopped by an 27Al nucleus will undergo nuclear capture, while about 40% will decay in orbit. To quantify the conversion probability, we define Rμe, which is given by the ratio between the μ-→ e- conversion rate and the nuclear capture rate [1]: Rμe= (Γ(μ- + N(Z,A)→ e- + N(Z,A)))/(Γ(μ- + N(Z,A)→ ν-μ+ N(Z-1,A))) . The upper limit on Rμe is 7⋅ 10-13 at 90% CL, set by the SINDRUM II experiment~\citeSINDRUM II:limit. The goal of the Mu2e experiment is to reach a sensitivity on Rμe of 8⋅ 10-17 at 90% CL. This represents a four-order of magnitude improvement over the current experimental limit. Mu2e will take its first data in 2027. The signature for the muon conversion is a monochromatic electron of 104.97~\si\mega\eV/c, an energy slightly below the muon rest mass. While the main experiment goal is to reconstruct the conversion electron, i.e., an event with a single track, there are motivations to develop an efficient tracking algorithm for reconstructing more simultaneous tracks. This could better constrain the background generated by pp-annihilation in the Al target and to search for other Beyond the Standard Model processes. In this paper, we present an algorithm designed to reconstruct multi-particle events.