Positron transport system for muonium-to-antimuonium conversion experiment

Muonium-to-antimuonium conversion experiment (MACE) aims to detect the charged lepton flavor violation (cLFV) process. A key component of MACE is the positron transport system (PTS) to collect and transport atomic positrons from antimuonium decays, which consists of an electrostatic accelerator and a solenoid beamline. Through field simulations in and particle transport simulations based on eant4, the PTS can achieve a geometric acceptance of the signal of 65.81(4)% along with a position resolution of 88 ( 1 ) μ m × 102 ( 1 ) μ m . The system achieves a transit time of 322.4(1) ns with a spread of 6.9(1) ns, which allows for a TOF-based rejection of internal conversion backgrounds by a factor of 10 − 7 . These promising results pave the way for new physics signal identification and background rejection in MACE and offer a novel paradigm for an internal transport system in high-intensity frontiers.