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Emulsion scanning: present status and plans for the coming run

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  1. Emulsion scanning: present status and plans for the coming run Giovanni De Lellis

  2. CS scanning

  3. CS scanning at LNGS

  4. Improvements in the Compton alignment of CS

  5. Tagging of CS tracks to reject physics background

  6. Analysis of the 2nd extracted brick • Sample of 65 analyzed second bricks • 29 with a positive result after CS scanning and analysis • 13/29 were actually 2nd extracted according to the probability map • 4/29 are now the 1st predicted brick according to the new version of the software (mu-shower, …) • The remaining 12/29 were extracted according to the scanning results and display of electronic detector hits • With the software version (not yet available in the Analysis follower) we have 20/29 events among the first and second most probable brick

  7. Brick finding • Including 4 events found with new software the finding rate is 17/65 = 26±5%  brick finding with 2 bricks 12 ~ 75% • Including new software release (not yet available on the analysis follower) 20/65 = 31%  12 ~ 77% • While currently (29/65) is 12 ~ 81%

  8. A look at the 12 events with the algorithm developed by the Dubna group • 5 are predicted as 1st brick • 5 are predicted as 2nd brick • 1 is predicted as 3rd brick • 1 is wrongly predicted

  9. 1st brick according to Dubna algorithm R11 C24 W11 R11 C24 W12

  10. 2nd brick according to Dubna algorithm R35 C11 W10 R36 C11 W9

  11. Wrongly predicted also by the Dubna algorithm R17 C26 W6 SIDE -1 R17 C26 W7 SIDE -1

  12. What about the other 17 events? • 10 are 1st brick • 5 are 2nd brick • 1 is 3rd, 1 is wrong 15 are among the 2 most probable 25/29 = 86% are among the 2 most probable

  13. Finding efficiency with the Dubna algorithm on already located events • Number of processed events: 317 located events • Wall finding efficiency: 0.880126 • Wall finding including the second brick: 0.996845 • Brick finding efficiency: • 1 brick extraction: 0.788644 250 • 2 bricks extraction: 0.962145 55 • 3 bricks extraction: 0.977918 5 • Number of extracted bricks: 375 • Number of not found bricks: 7

  14. Joint effort for brick finding • Set up a group with the involved people from scanning (Giovanni, Sato, Luillo) and electronic detector reconstruction (Dario, Anselmo, Antoine, Artem, Sergei) • Further studies on already located events to define a strategy for extraction

  15. Summary of the event location in Europe Upper limit in the event location NC: 91% CC: 95% Lower limit NC: 70% CC: 84% Dead material 8/369 = 2.2%

  16. Vertex location as a function of timein Europe achieved ~ 90/month in October

  17. Vertex location (all)

  18. Task of the scanning lab • Event location (priority) • CS to brick connection • Track scan-back or direct vertex search • Vertex confirmation by volume scan (11 plates) • µ finding for CC events • matching of emulsion tracks with TT • for NC events, the primary VTX is defined by the most upstream stopping point  important to check TT hits • Decay search • Measurement of all track segments in the plate immediately downstream of the vertex (important to improve the impact parameter determination) • Topological reconstruction • Daughter tracks of secondary vertices (when neutral) to be followed down for CS matching • Simulation needed to check the long flight charm efficiency (accounting for the track inefficiency) and possibly enlarge the scanning volume • Event publication

  19. IP reconstruction µ IP Pb Pb Missing segments make IP larger Important to measure the closest segment

  20. CS and brick assignment to the labs • CS are shared among Europe and Japan in equal parts • Bricks are shared among Europe and Japan in equal parts at the moment • Within Europe there is a dynamical approach with an initial value computed according to the number of microscopes

  21. Dynamical approach in the brick assignment in Europe Initial value Current brick sharing

  22. Event location in Europe (as of March 5th) Lab Assigned Received Located Passing Dead mat MF(%) MF = (Located + passing through + dead material)/Received Frascati and Rome started recently, statistics is not enough yet

  23. Current assignment fractions The fractions are revised periodically (every 1-2 months) The expected rate is 80  90% If lower  reduce to restore the expected rate (lab overloaded) If above  increase to speed up the analysis

  24. Continuous feedback between CS and brick analysis New predictions from CS with the ¾ method First reconstruction from CS double base-track predictions Vertex in ECC

  25. Additional scanning activities for Monte Carlo validation • Collect a sample of CC events (fully reconstructed) to check the Monte Carlo event simulation • Our ultimate goal is to collect ~ 1000 events • Medium term goal: ~200 events by the end of this year • Start with the calibration for momentum measurements • low energy µ for independent measurements and cross-calibration • event selection is ongoing (~30 events estimated…) • Then, measure primary tracks • select only upstream events  on average ~40 films to be scanned + event analysis  2 days/event (rough estimation) • Scan-forth of all tracks attached to the primary vertex done at same time of momentum measurement • For scan-forth measurements already collected  need momentum measurement for Pt analysis

  26. Track multiplicity at primary vertex

  27. QE-like events Scattering angle Transverse momentum Spectrometer momentum

  28. 0µ fraction