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Station 5 status

Station 5 status. Scintillating fibre tracker. The scintillating fibre tracker reconstructs muon tracks before and after the MICE cooling section in 4 T magnetic field to measure the relative change in emmitance of the muon beam The tracker consists of five planar scintillating-fibre stations

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Station 5 status

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  1. Station 5 status

  2. Scintillating fibre tracker • The scintillating fibre tracker reconstructs muon tracks before and after the MICE cooling section in 4 T magnetic field to measure the relative change in emmitance of the muon beam • The tracker consists of five planar scintillating-fibre stations • Each station is composed of three planes of scintillating fibres laid out with 120 degrees radial spacing • Each fibre plane is comprised of a ‘doublet-layer’ in which the fibres in the first layer of the doublet are interleaved with those in the second

  3. 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 • Station 5 – 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

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

  5. Bundling - ii comb

  6. 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

  7. Connectorisation - ii Fibre radius guide is used for connectorisation “Bridge” a tool for QA Bridge with connectors in place

  8. QA– counting - i • Bundling/Connectorisation most labour intensive, source of errors • 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 then analysed by software Fibre bundles in comb Fibre bundles in connector

  9. QA – 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/bridge • Seven fibres in a bundle identified with different colours

  10. QA – scanning - i • If counting QA 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 • Trace sum of CCD intensity for 9 pixels around fibre centre • Bottom fibre signal distortedby the top fibres and glue UV LED Top fibres Bottom fibres

  11. QA – scanning - ii peak • 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. Each Xcorresponds to peak Seven X in each bundle

  12. QA – scanning - iii • Time interval of each peak checked as well • Negative interval if there is fibre swapped between bundles • Mean = 4.24 frames => 212.17 micronagrees with measured mold pitch of 426/2 micron

  13. Gluing • Fix vacuum chuck, carbon-fibre station frame to gluing jig • Then glue them together

  14. Potting, cutting • Pot fibres to connectors, then apply glue to stiffen fibres then cut them before polishing Apply glue Cut fibres After cutting Ready for polishing

  15. Polishing • Polish connector surface with diamond fly cutter • We had problems not seen in prototype stations • Scratches • Broken cladding layer • After applying optical grease, will not cause transmission problem • Will use new diamond fly cutter • Cutter can degrade over time

  16. Plans • Test with cosmic ray • Polish with new diamond fly cutter • Measure uniformity of height (z) of station

  17. Summary • Station 5 built with new manufacturing procedure, which proven to work • Ready to be tested o view X - mold4#X / 22 aug 206 - 1491 fibres o view W - moldX#X / 17 aug 2006 - 1491 fibres o view V - mold4#1 / 15 aug 2006 - 1492 fibres; one extra! • 4474 350 micron fibres successfully bundled and connectorised by hand!

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