1. π 0 search N.Kitagawa Flab Nagoya University OPERA Emulsion Workshop 2008/01/22-23

2. Pi0 search strategy Additional NetScan data taking 1.Select segments extrapolated to VTX point allowed 50mrad angular difference by using 0 skip linklet 2.Check the all candidate tracks 3.Display all selected tracks and judge whether they are electron or not 4.Manual scan check.. VTX plate 1x1cm 2 2x2cm 2 5 plates 10 plates

3. Event 180277945 CC Mu+ 8.7 GeV/c HPT SM1 Not workin g Ev18027794 Brick#33540

5. CS scan an SB results Scanning Area (40mm x40mm) and (122mm x 95.5mm) 4 hold selection Prediction angle: 0.038, 0.220 Difference from prediction angle: -0.025,0.011 Difference from prediction positions: (3.1, -1.4) mm. Scan location  Stopping at pl 56 Ev18027794 Brick#33540

6. Track found on CSd (Blue thick line) Ev18027794 Brick#33540

7. X Z Y After 1st step (select segment pointing to VTX)

8. X X X X X Y Z After 3rd step (select correct tracks) Muon (p=2610 +979-485 MeV/c) partner trk1 (p=234 +96-49 MeV/c) partner trk2 partner trk3 (p=932 +235-101 MeV/c)

9. Manual Scan results 3 tracks +1 black track at 1ry vertex. 1 track stop at pl54 decay or 2ndry!!. 2 electron pairs have been found –@pl51 0.2238 -0.1117 57046.1 40539.9 0.2216 -0.1186 57048.1 40536.5 –@pl50 0.0731 -0.0819 56180.9 40611.9 0.0628 -0.0945 56178.2 40608.9 Ev18027794 Brick#33540

10. 1ry vertex positions x: 55633.7 y: 41267.8 z: -424.8 e-pair vertex positions @PL51 x: 56965.7 y: 40580.0 z: 359.1 opening angle: 7.24mrad e-pair vertex positions @PL50 x: 56162.6 y: 40632.3 z: 247.7 opening angle: 28.0mrad

11. Momentum of electrons (measured by angular method) p=244 +40-36 MeV/c p=467 +76-91 MeV/c p=201 +61-38 MeV/c p=160 MeV/c PL50 PL51