Particle identification in the TREK/E36 experiment at J-PARC

The TREK/E36 experiment conducted at J-PARC in Japan aims to test lepton universality by a precise measurement of the ratio of decay widths of the decay channels Κ_e2 and Κ_μ2, R_K =Γ(Κ_e2)/Γ(Κ_μ2), and to search for exotic Κ⁺ decay modes accompanied by light neutral bosons, by utilizing a Κ⁺ beam stopped in a scintillating fiber target, a highly segmented CsI(Tl) photon calorimeter covering 75% of 4π, charged-particle tracking through a 12-sector toroidal magnet, and particle identification systems. Since the R_K value is of order 10^-5, the e⁺ discrimination from other particles is one of the most important issues. Three independent detection systems: time of flight between TOF1 and TOF2, an aerogel Cherenkov detector (AC), and a lead glass Cherenkov detector (PGC) were used for particle identification (PID). In this talk the status and approach of the PID analysis will be presented.