1. Automatic Track Follow Program A program to trace a given set of tracks automatically –Event location for PEANUT and OPERA –DONUT “not-located” events Koichi Kodama Aichi University of Education DONUT meeting 2005/05/28

2. low noise  require existence of micro tracks on both sides ( base track ) high efficiency  scan at lower PH threshold Base Track Recognition Low PH scan takes time restricted scan in position and in angle space

3. At least a micro track should be detected in one of 2 sides of a sheet by Normal PH scan. The other side are checked with LOW PH threshold scan for its existence if it is not found by Normal PH scan Idea for base track recognition in a plate

4. Algorithm for Point Scan Input : position and angle of a track to be found Scan on both surfaces with Normal PH threshold A Base Track exists ? ( allowed distortion < 50mrad ) A Micro Track exists in either side ? Found Not Found Scan on the other side with LOW PH threshold A Base Track exists ? ( allowed distortion < 50mrad ) YES NO YES NO Found Not Found NO YES

5. Test with OPERA emulsion sheet 1mm Pb 2GeV pi- 5x10 3 /cm 2 Point scan with this algorithm Normal PH threshold = 8 Low PH threshold = 6 Sample : 537 tracks found in 4 sides ( pl.51A & pl.50A ) 4mm x 3mm area pl.51A pl.50A

6. Micro Tracks UP side

7. Micro Tracks Down side

8. Base Tracks

9. Efficiency @ sqrt(chi2/ndf)<3 This algorithm0.985 ( 527 ) U only0.933 ( 501 ) D only0.944 ( 507 ) Both U&D0.881 ( 472 ) evaluated with 537 tracks

10. Base Track PH

11. Plate to Plate Connection 1.A set of tracks to be followed are given. 2.Find alignment between plates 200micron x 200micron area scan for DONUT Choose 10 tracks among given tracks and require >5 tracks to match 3.Check existence of all tracks Connection judged at Z in the middle Multiple candidates are kept

12. Test with OPERA type brick 1mm Pb 2GeV pi- 5x10 3 /cm 2 follow down 1mm Pb Sample : 537 tracks found in 4 sides ( pl.51A & pl.50A ) 4mm x 3mm area skip follow down search window +/- 16micron +/- 20mrad for 1 plate jump

14. Last Found Plate by OXX rule Plate #515049484746454443424140 Last found plate 003122012338512 For 1mm thick Lead, int ( high energy protons ) = 0.6% thus … int ( high energy pions ) ~ 0.6% x 2/3 = 0.4% 537 x 0.4% = 2.1 search window +/- 16micron +/- 20mrad for 1 plate jump

16. Multiple Connection

17. Test with DONUT not located event Scan Back 5246 tracks found on CS ( both sides ) & SS ( down only ) 16mm x 15mm  < 200mrad ECC200

20. Last Found Plate by OXX rule Plate #12345678 Last connected plate 27019548652311053821 search window +/- 16micron +/- 20mrad for 1 plate jump Problem in Scanning

21. search window +/- 16micron +/- 20mrad for 1 plate jump

23. Multiple Connection

24. Summary Base Track recognition algorithm works. –Efficiency ~ 0.98 possible for OPERA type sheet Track follow program works. –~1 sec/track for Point Scan –1000 tracks corresponds to ~30 min/sheet Good filter program is needed to suppress grow up of paths to follow.