1. NC like event location 9 th /Dec/2006 OPERA Emulsion Work Shop T. Fukuda, K. Morishima, N. Kitagawa @ Nagoya univ

2. NC like event In OPERA case, CCev:NCev ~ 3:1. In nu tau CC ev, 1mu ev : 0mu ev ~ 1:4. So, in NC like ev, event rate of nu tau CC ev is ~10 times than CC ev. NC like event is very important. No mu prediction, for event location. We must scan back all picked up trks on CSD. Idea to locate NC like event OPERA film is very precision 3D tracker. By extrapolating scan back trk before stopping, human eyes can recognize 1ry VTX position. I developed a monitor program helping this recognition (called “VTX monitor”).

3. Trial of scan back using VTX monitor Test Sample → PEANUT BL040 CSD Scan → pl01, pl02 56cm 2 (S-UTS) picked up 903 CSD trks Using SFT information, reject Cosmic rays and Rock muons (next Nonoyama talk). → 165 trks Scan back 165 trks by point scan using UTS. Scan back procedure pre scan (for alignment) → prediction scan → eye check Now PL18 No trk found in 3 consecutive plates → trk is Stop. 96trks is stop (/165). CSD (PL1,2) PL18 BL040 ν

4. VTX monitor Demonstration

5. Summary To study of NC like event location Developing VTX monitor. Reject low energy electron(CSD-pl03). Upto PL18 scanning, I found 3 nu-int candidates. Future Plan ・ Polishing VTX monitor. pi/e separation, e-pair judgment,,, ・ Analysis of found VTX ・ Using only CSD trk data can be useful for Brick finding.