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Status of Forward Pixel Survey

Andrei Gritsan, Mikhail Kubantsev, Nhan Tran*

TB Meeting 16/04/08

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Concept/Formalism• Each surveyed hierarchy consists of a system of

points• By use of rigid body formalism, we can determine

how much each object is rotated and translated. We overlay survey and reference (fiducial) systems to determine ΔR and ΔΩ

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• i = 1…N is the number of substructures per hiearchy• j = 1…n is the number of points per substructure• rij is the position of each point; mij is the mass of each point• drij is the difference between reference and surveyed systems

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Recap of Forward Pixel Survey

Panel SurveyHalf Disk Survey

Half Cylinder Survey

Survey Hiearchy:• Module• Panel• Half Disk (one-side)• Half Disk• Half Cylinder• Pixel Endcap

Software Hiearchy:• Module• Panel• Blade• Half Disk• Half Cylinder• Pixel Endcap

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Half Disk Level Survey• Using CMM measurements of fiducial points on

modules, find displacements of:• Modules on a Panel• Panels on a Half Disk (one-side)

• Used stainless steel balls as reference targets to join two sides of a Half Disk

• “Finger-printing” of panels on half disk using known displacements of modules on a panel to find misidentified panels

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Half Disk Error Analysis• Errors at each hierarchy

propagated by measurement uncertainties

• Using Toy MC analysis, we propagate measurement uncertainties into displacement uncertainties• Module uncertainty is dominated

by time/installation• Panel/Blade uncertainty

dependent on the number of point surveyed

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Panel Toy MC Study

Survey errors used byalignment group

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Results of Forward Pixel Half Disk Level Survey

• RMS values for module, panel, and blade local displacements

• Values considered as placement uncertainty • Given in local frame; rotations given in Euler angles

u (μm) v (μm) w (μm)

(mrad) (mrad)

(mrad)

Module 60.3 46.7 14.3 0.41 1.34 2.08

Panel 46.3 40.9 54.5 3.84 3.66 2.03

Blade 71.4 71.7 71.5 3.56 3.83 2.63

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Recap of Forward Pixel Survey

• Surveyed Panel, Blade, Half Disk hierarchies via CMM measurements at FNAL• Survey of about 200

production panels with CMMmeasurements

• Survey complete of all 8 FPix Half Disks

• Error analysis at all hierarchy levels

http://indico.cern.ch/conferenceDisplay.py?confId=17330

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Half Cylinder Survey• To create a half cylinder system, three sets of

measurements used1. Half Disk CMM measurements of sensor fiducials and

1mm phototargets for each side at FNAL2. Half Disk PHG measurements of 1mm and 3mm

phototargets at FNAL3. Half Cylinder PHG measurements of visible 1mm and

3mm phototargets with half disks inserted at CERN

• In joining measurements (1) and (2), usually are about 30 common targets (next slide)

• In joining measurements (2) and (3), common targets vary between halfdisks (next slide) QuickTime™ and a

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Half Cylinder Survey

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Common targets in creation of Half Disk System

Common targets in creation of Half Cylinder System

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Half Cylinder Survey Results

• Results for each half disk in the half cylinder• Values are presented about a point defined as the

sum of the positions of the daughter modules of each half disk in the CMS global frame

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Forward Pixel Survey Object• A comparison of FPix Survey with Ideal Geometry

• All Survey measurements for each hierarchy are compiled and applied to the CMS geometry• Results are saved to DB• A typical plot: Δr/Δz/rΔ vs. r/z/