1. Relative alignment of LXE and DCH using AIF
Tae Im Kang and William Molzon
Oct
MEG Coll Meeting

2. Outline AIF event selection Analysis of relative alignment using AIF
Results
Relative alignment for 2009, 2010 data
Relative alignment stability check for 2011 data by W. Molzon
Comparison
Relative alignment using Cosmic ray for 2009 data by T. Iwamoto etc.

3. motivation Annihilation in Flight (AIF) is background event of MEG
AIF pattern recognition by G. Lim and W. Molzon
AIF event from reconstructed data
Good resolution
Relative alignment of LXE-DCH using AIF

4. analysis Run number Reconstructed data (open) Oldkalman used
2009 data : 51xxx – 64xxx (all statistics)
2010 data : 73xxx – 92xxx (all statistics)
Reconstructed data (open)
Oldkalman used
MEG trigger (Trigger = 0)

5. Looking for AIF ievent=315 of run73999 aif candidate ★ gamma position
★ projection on LXE from last Hit using px, py, pz
At last hit : Δθ = θϒ – θ aif , ΔΦ = Φϒ – Φ aif
At projected position on LXE : ΔX = Xϒ – X proj, ΔY, ΔRphi (on circumference), ΔZ

6. Looking for AIF Positron track selections
Best chi-square (GhostRank = 0)
Time from DCH (TICIter = 0)
single hit at last chamber of the track
aif candidate

7. Cuts : dT -> dZ

8. Cuts: … dZ -> dRphi, dE, Eϒ, Ee
1hit + dZ + dT

9. Cuts : no wire# 0 wire # 0 - 8 integrated in chamber all 288 wire

10. Selected AIF

11. Gamma correction Gamma (from Target) AIF gamma (not from Target)
Correction for reconstructed gamma position by Y. Uchiyama
Assuming gamma coming from Target
Xgamma, Ygamma : correction not needed
Zgamma in reconstructed data : already corrected
Correction parameter : cm/rad by Y. Uchiyama (MC)
AIF gamma (not from Target)
different incident angle in XY and ZR plane
Using correction parameter cm/rad

12. AIF incident angle correction in XY plane
UVW position
gamma from target
incident angle wrt. Perpendicular = 0 deg.
gamma from AIF
incident angle is about 17 deg.
AIF incident angle correction
1.855 cm/rad = L / incident angle (rad)
L ~ 0.55 cm for incident angle of 17 deg. (0.30 rad)
rotation about theta’ = L / gamma radius L
Aif incident angle
theta’
target
aif position
gamma radius

13. AIF incident angle correction in ZR plane
Zgamma_Target, corrected by cm/rad * incd_Target
Vertex Z
Incd_Target
aif positon
Zgamma_uncor ~ Ugamma,
uncorrection
Incd_AIF
Zgamma_incd_AIF,
corrected by
1.855 cm/rad * incd_AIF
Zgamma_Target
Zgamma_uncor
LXE
UVW position (reconstructed info) R

14. Zϒ – Z proj (= ΔZ ) of AIF event with different incident angle correction
Zgamma_AIF
Zgamma_Target
Zgamma_uncor

15. alignment check if LXE shifted by + 1 mm in Y-axis, (ΔY > 0)
Xg – X proj
gamma
aif projection
phi angle ΔY
Yg – Y proj 
180 deg  
phi angle
Rphi g – Rphi proj Y
gamma radius X
phi angle

16. alignment check if LXE shifted by - 1 mm in Y-axis, (ΔY < 0)
Xg – X proj
gamma
aif projection
phi angle ΔY
Yg – Y proj
180 deg   
phi angle
Rphi g – Rphi proj Y
gamma radius X
phi angle

17. alignment check if LXE shifted by + 1 mm in X-axis, (ΔX > 0)
gamma
aif projection
Xg – X proj
phi angle ΔY
Yg – Y proj
180 deg   
phi angle
Rphi g – Rphi proj Y
gamma radius X
phi angle

18. alignment check if LXE shifted by - 1 mm in X-axis, (ΔX < 0)
gamma
aif projection
Xg – X proj
phi angle ΔY
Yg – Y proj
180 deg   
phi angle
Rphi g – Rphi proj Y
gamma radius X
phi angle

19. 2010 data Y = 1 ± 0.8 mm, Rphi = - 1 ± 0.6 mm at phi = 180
Fitting range : 140 ~ 220 deg.

20. 2010 data: Yϒ - 2 mm
ΔY slop => ΔX < 0

21. 2010 data: Xϒ + 2 mm, Yϒ – 2 mm

22. 2010 data
ΔZ = - 3 ± 1 mm, at Zϒ = 0

23. 2010 data: Zϒ + 4 mm

24. 2009 data Y = - 1 ± 0.6 mm, Rphi = 1 ± 0.6 mm at phi = 180 deg.
Fitting range : 140 ~ 220 deg.

25. 2009 data: Yϒ + 2 mm
ΔY slop => ΔX > 0

26. 2009 data: Xϒ – 2 mm, Yϒ + 2 mm

27. 2009 data: Xϒ + 2 mm (wrong dir), Yϒ + 2 mm

28. 2009 data
ΔZ = - 4 ± 1 mm, at Zϒ = 0

29. 2009 data: Zϒ mm

30. Cosmic ray and AIF for 2009 data
Cosmic ray, technical note by T. Iwamoto etc.
Δ V = -1.9 ± 0.7 mm
Δ Z = -6.1 ± 0.3 mm
AIF (preliminary results)
Δ Y = ± 0.5 mm
Δ Rphi = - Δ V = 1.0 ± 0.5 mm
Δ Z = ± 1 mm
Consistent results in sign and value within 2 mm error

31. Resolutions of ΔY, ΔRphi and ΔZ
Typical resolution of 25 mm for ΔY and 18 mm for ΔZ
Broaden distribution due to the gap of 3 mm between planes
if AIF happens in two foils with same probability
3 mm / 14 mm = 0.2 deg = 3.7 mrad

32. Stability During 2011 Run W. Molzon beginning end X residual
Y residual

33. Residuals for X Offset Changes
W. Molzon
Xϒ + 20 mm
0 mm
Xϒ - 10 mm dY dX

34. Conclusions AIF event can be used for relative alignment research
Sign determination and relative alignment value within 1 mm error (stat.)
Relative alignment (preliminary)
2009 data
ΔY = - 1 ± 0.8 mm, Δ Rphi = 1 ± 0.6 mm at phi = 180 deg.
Δ X > 0 from ΔY slop
2010 data
Δ Y = 1 ± 0.6 mm, ΔRphi = -1 ± 0.6 mm at phi = 180 deg.
Δ X < 0 from ΔY slop
Cosmic ray and AIF show consistent results for 2009 data
Same sign and consistent value within 2 mm error
Outlook
reanalysis of data with newkalman
technical note in 1 month
how to incorporate in MEG analysis

35. backup

36. geometry effect in cosmic ray
TN 69 by T. Iwamoto etc.
geometry effect in cosmic ray
November
June
November
June

37. TN 69 by T. Iwamoto etc.
Cosmic ray by T. Iwamoto

38. TN 69 by T. Iwamoto etc.
cosmic ray shower different from gamma in general, but deltaZ at Z= 0 should be same
18.5 deg
72.5 deg
(deg)
displacement of delta rphi (red) due to geometry
= cm /deg * 18.5 deg = cm
(deg)
slop = 4cm / (113 deg – 64 deg) = cm/deg
= 4.87 cm / rad.

39. 2009 data : geometry effect aif suppresed All gamma AIF event
Y g – Y proj
aif suppresed

40. 2010 data: geometry effect
All gamma
AIF event
aif suppresed