Takashi Matsushita

t.matsushita@imperial.ac.uk

Imperial College

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Quality Control of Station Assembly

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Stations built so far Prototype stations 1 – 4; had problems:

Did not know which channel is the centre of the station Lots of problems on channel mapping Light loss due to hole mis-alignment at optical connectors

Fifth station – the first production version for trackers Built with new procedure that incorporates quality control to

rectify any errors occurred during manufacturing. Improvements:

Centre fibre clearly marked during ribbon production Optical connector hole alignment checked Number of bundles in a connector checked Number of fibres in a bundle checked Sequence of fibres checked

Should have rectified problems encountered for stations 1 – 4, yet to be confirmed

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Station assembly overview First doublet-layers are manufactured at FNAL

350 m diameter fibres are laid-out on a mold with groove pitch of 426 m;1491 fibres used per doublet-layer

Then make bundles of seven fibres, put them through optical connectors, then layers stacked and glued

Quality Control before gluing them together

Centre fibre

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Bundling - i Make bundle of seven fibres starting from the centre fibre

Seven fibres held together with rubber tube => single read-out channel

“comb” is used for bundling and QC procedure; bundles are stacked in grooves of the comb, channel map defined

bundles of four columns (5-6-5-6 or 5-6-5-4) for one connector

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Bundling - ii

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Connectorisation - i A 22 way optical connector mates seven

scintillating fibres with one clear fibre waveguide;

alignment of connector holes at scintillating fibres and clear fibres sides are checked with ‘go/no-go gauge’

The scintillating fibre bundles are threaded through one of 22 holes of optical connector

Connectorisation mapping for view X

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Connectorisation - ii

“Bridge” a tool for QC

Fibre radius guide isused for connectorisation

Bridge with connectorsin place

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QC - setup Bundling/Connectorisation most labour intensive, source of errors We perform QC step after bundling/connectorisation with the setup

shown

Translation stage

LED (20 mW, = 405nm) / optics

Doublet layer

CCD

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QC– counting - i First number of bundles for a connector as well as number of fibres

in a bundle are checked after bundling and connectorisation CCD images of one connector worth of bundles are taken

Fibre bundles in comb Fibre bundles in connector

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QC – counting - ii Then software identifies bundles and fibres in the CCD image taken

Notifies operator if there are any failures

Twenty two bundles identified for comb/connector Seven fibres in a bundle identified with different colours

Analysed comb image Analysed connector image

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QC – scanning - i If counting QC was OK, move on to fibre

sequence check by LED scanning Scan fibre plane with UV LED at 1250

micron/seconds Capture image at 24.98 frames/seconds

=> 50 micron/frame [movie]

Trace sum of CCD intensity for 9 pixels around fibre centre

Bottom fibre signal distortedby the top fibres and glue

Top fibres

Bottom fibres

UV LED

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QC – scanning - ii Find frame # of intensity “peak” of each fibre;

Frame # of leading edge = maximum intensity * 0.5 Frame # of trailing edge = maximum intensity * 0.5 Frame # of ‘peak’ = (leading edge + trailing edge)*0.5

Plot frame # of intensity ‘peak’ of each fibre;

As frame # increases bundle # (channel number) increases, no overlaps of X

Fibre sequence as well as bundle order should be OK before gluing a ribbon

Max.

“peak”

Each X corresponds to ‘peak’Seven X in each bundle

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QC – scanning - iii

Samples of errors identified during assembly

Fibre swap between bundles17&18 and 19&20

Wrong bundle order

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QC – scanning - iv Time interval of each ‘peak’ checked as well Negative interval if there is fibre swap between bundles

mean = 4.24 frames => 212.17 micronagrees with measured mold pitch of 426/2 micron

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Point of no return - gluing Fix vacuum chuck, carbon-fibre station frame to gluing jig

Then glue them together

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Potting & polishing Pot fibres to connectors, then apply glue to stiffen fibres then cut

and polish

Apply glue Cut fibres

After polishing

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Summary

New station assembly procedure with QC process incorporated worked out to overcome problems seen in prototype stations

Station 5 built with new manufacturing procedure, which proven to work

4473 350 micron fibres successfully bundled and connectorised by hand

Ready for test with read-out

Station assembly is underway with the new assembly procedure