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STT & SMT Assembly Precision

STT & SMT Assembly Precision. Method Results no in situ alignment w/in situ alignment Conclusions. Stress difference between assembly precision and knowledge of assembly. Simulation Method. Tests Generate tracks with “true” (non ideal) geometry

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STT & SMT Assembly Precision

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  1. STT & SMT Assembly Precision • Method • Results • no in situ alignment • w/in situ alignment • Conclusions Stress difference between assembly precision and knowledge of assembly Hobbs, Silicon Mtng

  2. Simulation Method • Tests • Generate tracks with “true” (non ideal) geometry • Reconstruct with different(ideal) geometry • Simple simulation • Correct SMT geometry (RECO) • Intersect helices and ladders • STT will use alignment • f, every cluster (zL=0) • r, avgs. in matrices (look up) Caveat: STT group not approved this yet... Hobbs, Silicon Mtng

  3. Move detector in X by 30 mm Tilt detector about X by 100 mrad Code Sanity Checks • Look at b(reco)-b(true) vs. ??? Hobbs, Silicon Mtng

  4. Result I: No in situ Alignment This relies completely on assembly precision…* • True, non-ideal for generation • Assume ideal geometry for reco 300 mrad 300 mrad 250 mm 100 mm *This also limits uncertainty on alignment knowledge for positions Hobbs, Silicon Mtng

  5. Result II: Perfect f This relies on assembly knowledge • True (non-ideal) for generation • For reconstruction • true f from true geometry & • matrices(radii) from ideal no problems if dr < 200 mm and tilt < 250 mrad Hobbs, Silicon Mtng

  6. 1 (1+2 )*(1 + )2 1 rc2 df2 = * * (dx2 + drc2) + dfc2 x rc x rc ( ) 2 ( ) 2 x rc ( ) 2 drc = 100 mm drc = 50 mm One line/layer smaller radii, larger effect f Precision (df) • Do we really know df well enough using alignment? • Alignment goal: Doesn’t effect hit resolution by more than 10%... • Look at (limited) effects http://sbhepnt.physics.sunysb.edu/ ~hobbs/alignment/align.pdf X = SMT position (local) rc = Radius at ladder center fc = f at ladder center Layer 1 Layer 8 Hobbs, Silicon Mtng

  7. Conclusions • Assembly requirements interplay with alignment status • Constraints • Knowledge, offsets ^beam 25 mm • Knowledge, radial offsets: 70 mm • Assembly tol., angles 200 mrad • Not met, require in situ alignment. • Time dependence? • Systematics in alignment (CDF)? • Absolute tolerances only on angles Hobbs, Silicon Mtng

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