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Tower A software alignment

Tower A software alignment. 28 january 2005. Ladder alignment on a tray. MCM side. The ladders alignment is measured with a CMM with optical probe (3 points per ladder) in G&A .

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Tower A software alignment

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  1. Tower A software alignment 28 january 2005

  2. Ladder alignment on a tray MCM side The ladders alignment is measured with a CMM with optical probe (3 points per ladder) in G&A . The small dispersion of the data (s=18mm, planarity ~ 0.1mm) allows to consider the 4 ladders of a tray plane as a single detector. We do not need to introduce ladder per ladder alignment corrections

  3. Tower B ladders alignment

  4. SSD plane Pins plane Tray thickness The tray thickness is also measured. The results are well within the design specs * Distance from the SSD to the alignment pins on the thermal boss

  5. residual/mm x•y orth. coordinate/mm profile histogram residual/mm orth. coordinate/mm Software tray alignment: rotation A parallelism error generates an error which is proportional to the orthogonal coordinate (v) of the event. v has to be extrapolated from the fitted 3-dimensional track. The fit of the profile histogram gives immediately the rotation tan() of the plane (parameter p1). p0 again is a measure horizontal shift, but here at v=0 (the preceeding methods give the shift at the center of the wafer).

  6. x=tg()•z Theoretical SSD height z True SSD height Software tray alignment: vertical In similar way to the horizontal case, it is possible to determine the relative height in the tower of a SSD plane studying the residual distribution as a function of the incident angle  of the tracks. residual/mm cot() profile histogram The fit of the profile histogram gives immediately the vertical shift (parameter p1), and once again the horizontal (p0). residual/mm cot()

  7. shift Software tray alignment: horizontal before after A shift of a plane with respect to the other ones generates a residual distribution not centered around 0 (measured points - reconstructed trajectory). An iterative algorithm allows to align the detectors so that all the residual distributions are 0 centered.

  8. Coordinate shifts X Shipment to SLAC Sidewalls assy TV test Vibe test The tower jigs aligns the pins that have been used to align the ladders (the best reference) When the pins on the alignment wall of the tower jig are removed, the sidewalls partially realign the trays to their external dimensions with a max alignment loss ~0.1mm Sidewall removal

  9. Coordiante shifts Y These trays are aligned on the tower jig on a structural closeout. The relative alignment of the ladders is poorer, but the max loss of alignment after sidewalls assembly is only 0.05mm Reference wall of the tower jig

  10. Ladder parallelism Parallelism for X trays ± 0.1mm Parallelism for Y trays ± 0.2mm except for layer Y2 (light tray 016, top side) with an anomalous parallelism of 0.45mm The general difference in parallelism between X and Y trays can be related with the tower jig. No explanation for the Y2 anomalous parallelism.

  11. Coordiante shifts Z The software determination of the tray position in Z is poor as shown by the differential plot Z error ~±0.2mm

  12. Tower B results

  13. Conclusions • Good data! • Good alignment and parallelism of the trays, typical values in the ±0.2mm range over the whole tower • Very good mechanical stability: • limited alignment loss after sidewalls assy • no alignment loss after vibe, thermo-vacuum, a single sidewall dismounting and shipment to SLAC • Tower B data are slightly better than tower A data

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