Electron Veto Counter Masashi Kaneta 2006/4/13 K0 meeting Masashi Kaneta, Tohoku Univ.
The Main back ground: e+e- pair • e+e-:Photon conversion is the main background in the NKS2 experiment • Trigger will be made by (IH_Hits2 OH_Hits2) • Those tracks will be on a plane • e+e- direction is almost same with photon • bended in a magnet field • Need to remove them on a trigger level Masashi Kaneta, Tohoku Univ.
Trajectory of e+e- • 0.0-1.2GeV/c of electron/positron • Bremsstrahlung photon energy is up to 1.2GeV • Energy sharing Ee/Eg is 0 to 1 • Hits on both IH and OH 108 [eV] 109 [eV] Rev. Mod. Phys. 13 (1941) 240 107 [eV] 0.0 1.0 Trajectories of electron as a function of momentum (0.2–1.2 GeV/c with 0.2 GeV/c step) Ee/Eg Masashi Kaneta, Tohoku Univ.
Hit distributions at OH position e+e- • Monte-Carlo studies are done by Kenta Futatsukawa • Hits information from OHH and OHV • there is a overlap around 55 degree p+ from K0S p- from K0S z [cm] p from L p- from L q [degree] Masashi Kaneta, Tohoku Univ.
Design • 5 cm height • same with Previous experimet (NKS) • Hybrid counters • Plastic Scintilator counter (1cm thickness) • Lucite Cherenkov counter (2cm thickness) • will place on the same plane • Separated as 4 counters • to avoid absorption of light in the counter • but can not have so many counters • PMT’s used in NKS will be recycled Masashi Kaneta, Tohoku Univ.
Design Masashi Kaneta, Tohoku Univ.