Search for CP violation in the lepton sector

1. GUT D2 CP violation in the quark sector CP violation in the lepton sector D1 D1’ magnet D2’ ⇒ CP violation o-Ps→3γ o-Ps o-Ps γ o-Ps γ e- e+ γ detector D2 detector D2 detector D1 detector D1 137Cs spectrum 511-511 coincidence If we assume ,　・・・ Our Goal ΔCCP～10^-2 φ[°] M.Skalsey and J. Van House, Phys. Rev. Lett. 67 (1991)1993 Search for CP violation in the lepton sector ICEPP Univ. of Tokyo Kazuyuki Nishihara Physics Motivation Detector Setup CP violation in the quark sector has been established, but there is no evidence in the lepton sector. We optimized the configuration of the detectors. ・CKM matrix ・B physics ・MNS matrix ? ・neutrino oscillation ? violated at ~ 10^-3 invariance confirmed at only 10^-2 Ortho-Positronium System The ortho-positronium(o-Ps) provides a good system for the CP violation search. Statistics Results of the geant4 simulation In this setup, we can store 1.1×10^8 events / 3 months (22Na 100kBq) CP violating angular correlation enough to realize 10^-3 sensitivity To reduce systematic errors 1) LYSO crystals LYSO crystals provide the good energy and time resolution. Detection Principle Experimentally we can derive CCP by measuring the following asymmetry LYSO crystal samples (2mm×2mm×10mm) ⇒reduction of the background ⇒stable against the pileup 2) 2 pairs of the detectors Preparing 2 pairs of the detectors enables us to correct the position of the source. • Rotation of the Magnet • By rotating the magnet, we can check whether the observed A is • a real asymmetry or not. (depends on the detector configuration) ⇒N+,N－depends on the direction (φ) of an external magnetic field. If CCP =0, N+= N－= N0 magnet ratio