SCT X-ray Alignment Software

1. SCT X-ray Alignment Software …and First Results James Loken – Oxford University

2. James Loken – Oxford University

3. Hardware Layout • Head ess. as for complete system • X-ray tube • Collimation system, ~80m and ~330m wide beams • Rotary stage, precise to 0.36’’ James Loken – Oxford University

4. Two Dimensional X-rayTriangulation Scheme Parameters: R, Ψ1 andΨ2 Measured: Φ1and Φ2 Result coordinates: r and φ Measuring tool: AEROTECH Rotary Stage, σ(φ) = 1’’ Accuracy achieved with the XTomo2D (at r ~ 500mm) : σ(rφ) = 5 μm σ(r) = 20 μm [see NIM, A457 (2001) 43-51] James Loken – Oxford University

5. X-ray Alignment • Current Methods • Simulation (of Hits) • HitToStrip • (real data could enter here) • StripToHit • Reconstruction (from Hits) • Analysis • Future • Incorporate Position and Tilt sensors • Diagnostic tools for Problem Solving • Calibration of X-ray Gun CopyHits (for debug) James Loken – Oxford University

6. Simulation • Loop over all 12 z positions •  Generate beams (4) at 231 phi values (1/5 of dPhi of beams) • Loop over barrels 3 – 6 •  Intersect 4 beams with barrel radius • Find appropriate detectors and intersect with beams • Write accurate strip hits (and gun z/phi) to hit and calib lists •  Write modules hit and calibration scanNo to scan list dPhi James Loken – Oxford University

7. HitToStrip • Read Scan list for modules hit • Read hit list for hit and gun pars • Generate 10K strips with Gaussian for r-phi and u/v-phi dets (beam 0.5 mrad x 20 mrad (?)) • Add 20% (?) random background strips •  Generate 2K hits per strip for Calibration beam (20 mrad) •  Include Strip Efficiencies for all strips (+/- 10% rms dist) •  Use Gaussian function value, and Random for errors • Store as histogram(s) • Save histograms (8+) as root file • Repeat for each Scan (231 x 12) James Loken – Oxford University

8. Module Strip Data James Loken – Oxford University

9. StripToHit • Read Scan list for modules hit • Find Root file • Find Histogram for each module • Search histogram (in each half) for largest peak •  Find scan and histo for Calibration data •  Correct strip histograms for Strip Efficiency • Fit limited range around peak to Gaussian • Extract peak value as accurate hit • Write accurate strip hit (and gun z/phi) to hit list • Repeat for each module • Repeat for each Scan (231 x 12) James Loken – Oxford University

10. Fit to Strip Data James Loken – Oxford University

11. Reconstruction Equations James Loken – Oxford University

12. …getting lazy now… James Loken – Oxford University

13. …and now… James Loken – Oxford University

14. Reconstruction Equations James Loken – Oxford University

15. Some Results James Loken – Oxford University

16. …and with Banana Distortions James Loken – Oxford University

17. X-ray Gun off centre James Loken – Oxford University

18. Recon Gun Shifted James Loken – Oxford University

19. Results forNo Effic, No Calibration James Loken – Oxford University

20. Results forWith Effic, No Calibration James Loken – Oxford University

21. Results forWith Effic, With Calibration James Loken – Oxford University

22. …and Barrel 4 James Loken – Oxford University

23. …and Barrel 5 James Loken – Oxford University

24. …and Barrel 6 James Loken – Oxford University

25. Conclusions • A good start has been made •  More work has been done • Some of the remaining work to be done: • A good Calibration of the Gun is needed • First attempts at a new method not good enough. • A good method must be found, H/W built, LabVIEW S/W written, data taken (DAQ working) – June 2004 • Laser & Tilt Sensors used – Sept 2004 • Integration of Online S/W (LabVIEW, DAQ, Sensors) – Nov 2004 • EndCap, full H/W & S/W programme – May 2005?? • Extraction of Detector positions – a few hours later! • Other work (Diagnostic tools, tests, studies) – in between times James Loken – Oxford University

26. Calibration Setup 25 cm phi0 R (x0, y0) phi1 35 cm 45 cm James Loken – Oxford University

27. Calibration Method • Start with 3 Dets at known Posn (+/- 30 microns) • Gun Params (R, phi0, phi1) unknown (3) • Gun Posn (x0, y0, phi00) unknown (3) • Chisq from Det fit + Det Posn  6 ind constr • (2 beams, 2 phi -> 4 x 3dets – 6 unknown = 6) • With best fit, fix gun Posn, and remove Det Pos constr • Chisq from Det fit only  0 constr • (4 x 3 dets – 3 x 3 dets – 3 unknown = 0) • Try many different errors added to Det Posn • Try many different starting values for Gun Param James Loken – Oxford University

28. Results for Detswith 20 micron error James Loken – Oxford University

29. Results for Detswith 2000 micron error James Loken – Oxford University

30. First Conclusions • The Gun Calibration method looks good • Implementation has started, results soon… • If it works, it will test most of the X-ray software and ideas James Loken – Oxford University

31. Peaks in Data James Loken – Oxford University

32. Peaks in Data James Loken – Oxford University

33. Fits to Peaks James Loken – Oxford University

34. Residules James Loken – Oxford University

35. James Loken – Oxford University

36. James Loken – Oxford University

37. Distortions James Loken – Oxford University

38. Surprises from Data • X-ray arms not symmetric • Narrow and wide beams swapped on arm 1 • Gives an offset of ½ beam separation = 0.0645 • Detectors in box not aligned in r-phi • Module rotated by 0.026 • r-phi = 0.026; stereo = -0.014 • Calibration changed by 1/cos(0.026) = 1.00034 or 37 microns for arm of 110 mm. James Loken – Oxford University

39. Results • Data gives good convergence • Independent of starting values of • Detector positions • X-ray gun parameters (armR, gunPhiAbs, gunPhiCen) • Best Values are • armR = 109.989 • gunPhiAbs = 1.68426 • gunPhiCen = -0.0686 James Loken – Oxford University

40. Conclusions • Calibration looks good • However… • Would like to check detector rotation • Should move X-ray gun in z • Would like to check calibration results • Need some (2 or 3) accurate detector positions • Otherwise, method looks very powerful James Loken – Oxford University