1. NA62 Collaboration Meeting – Anacapri 1 September 2009 Massimiliano Fiorini CERN

2. Data samples and reconstruction NA62 Monte Carlo only Gigatracker enabled: all other detectors excluded 2 data samples: Multiple Coulomb Scattering (MSC) switched ON MSC switched OFF ~200 M events generated for each sample Reconstruction for the Gigatracker hit information  pixels  clusters from cluster position extract kaon kinematic variables (p K, θ X and θ Y ) overlay implemented in MC but still needs some check: for the moment just single track in “trigger” time window

3. New classes added (1) class GigaTrackerPixel gathers all the hits’ energy belonging to the same pixel sensitive volume methods implemented: AddEnergy(Double_t) GetNHit() GetEnergy() SetTime(Double_t) GetTime() GetPixelID() GetPositionX() GetPositionY() SetClusterID(Int_t) GetClusterID()

4. New classes added (2) class GigaTrackerCluster collection of adjacent pixels (side-side, corner-corner) in a C++ vector methods implemented: AddPixel(GigaTrackerPixel) GetNPixels() GetPixelVector() GetDistance(GigaTrackerCluster) GetEnergy() GetTime() GetPositionX() GetPositionY() GetWPositionX() GetWPositionY()

5. Beam Spectrometer Layout pπpπ pKpK pυpυ pυpυ θ πK 13.2 m9.6 m 60 mm GTK2 GTK3 GTK1 2 nd achromat 3 GigaTracKer (GTK) stations 4 bending magnets (vertical view – above picture) plus 1 trim magnet (horizontal view) GTK geometry, materials, pixel structure and magnets implemented in Monte Carlo by Simone B. (see his presentation on April 1 st 2009, Physics Sensitivity WG)

6. Single Gigatracker Station 60 mm × 27 mm station dimensions 300  m × 300  m pixel cells 18 k pixels per station GTK station materials and thickness: Si sensor (200  m thickness) Sn-Pb bump bonds (15  m thickness, 10  m diameter cylinder) Si read-out chip (100  m thickness) carbon fiber support (100  m thickness) foreseen modifications: add rectangular 300  m × 400  m pixels (according to final sensor design) include geometry and materials of cooling system(s)

7. Beam line geometry

8. Vertical view (1) Δ 12 = 13.2 m 60 mm GTK2 GTK3GTK1 Δ 23 = 9.6 m Δ 13 = 22.8 m Δ bend = 3.6 m θYθY (BL) bend = 4.1695 Tm

9. Vertical view (2)

10. Error estimate ( θ Y ) ~5.4  rad ~13  rad~7.5  rad total contribution ~16.0  rad

11. Error estimate (p K ) 0.06%0.08%0.15% 0.12% total contribution ~0.22%

12. Horizontal view (1) Δ 12 = 13.2 m GTK2GTK3GTK1 Δ 23 = 9.6 m Δ 13 = 22.8 m Δ trim = 625 mm θXθX (BL) trim = 0.3002 Tm

13. Horizontal view

14. Error estimate ( θ X ) ~5.4  rad~2.6  rad ~13  rad~7.5  rad total contribution ~16.2  rad

15. Reconstructed kinematic variables

16. Kaon momentum (p K ) mean: 75 GeV/c r.m.s.: 0.773 GeV/c tails (mean ± 3 r.m.s.) amount to ~1.3 × 10 -4 of total

17. Kaon horizontal ( θ X ) angle mean: -1.2 mrad r.m.s.: ~92  rad

18. Kaon horizontal ( θ Y ) angle mean: 0 mrad r.m.s.: ~98  rad

19. Resolutions

20. Resolution on p K r.m.s.: 0.156 GeV/c (δp/p ~ 0.21 %)

21. Resolution on θ X r.m.s.: 16.3  rad sigma (gaussian fit): ~12  rad

22. Resolution on θ Y r.m.s.: 15.9  rad sigma (gaussian fit): ~12  rad

23. Multiple Scattering (MSC) switched off

24. Resolution on p K (1) r.m.s.: 0.141 GeV/c (δp/p ~ 0.19 %)

25. Resolution on p K (2)

26. Resolution on θ X (1) r.m.s.: 11.6  rad

27. Resolution on θ X (2)

28. Resolution on θ Y (1) r.m.s.: 11.1  rad

29. Resolution on θ Y (2)

30. Cutting on reconstructed momentum

31. Kaon momentum (p K ) mean: 75 GeV/c r.m.s.: 0.773 GeV/c cut distribution tails (mean ± 3 r.m.s.) reject ~1.3 × 10 -4 of events

32. Resolution on p K (1) r.m.s.: 0.150 GeV/c (δp/p ~ 0.20 %)

33. Resolution on p K (2) r.m.s.: 0.150 GeV/c (δp/p ~ 0.20 %)

34. Resolution on θ X r.m.s.: 15.9  rad

35. Resolution on θ Y r.m.s.: 15.5  rad

36. Conclusions and To Do List GTK (single) track reconstruction implemented resolutions as expected: δp K /p K ~ 0.21 % (r.m.s.) δθ X ~ δθ X ~16  rad (r.m.s.) complete reconstruction will be included when MC track overlay will be checked To Do list careful study of distribution tails include track quality parameter study correlations between variables use different PhysicsList simulate (and parametrize) charge sharing in nearby pixels update GTK MC description according to latest modifications

37. SPARES

39. Cutting on reconstructed p K, θ X and θ Y

40. Kaon momentum (p K ) cut distribution tails (mean ± 3 r.m.s.) for the three distributions reject 2.0 × 10 -3 of events

41. Kaon angles ( θ X and θ Y )

42. Resolution on p K r.m.s.: 0.150 GeV/c (δp/p ~ 0.20 %)

43. Resolution on θ X r.m.s.: 15.7  rad

44. Resolution on θ Y r.m.s.: 15.5  rad