Takashi Matsushita Imperial College T. Matsushita 1 Station 5 status

T. Matsushita 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

T. Matsushita 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

T. Matsushita 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 ( or ) for one connector

T. Matsushita 5 Bundling - ii comb

T. Matsushita 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

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

T. Matsushita 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

T. Matsushita 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

T. Matsushita 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 frames/seconds => 50 micron/frame Trace sum of CCD intensity for 9 pixels around fibre centre Bottom fibre signal distorted by the top fibres and glue Top fibres Bottom fibres UV LED

T. Matsushita 11 QA – 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

T. Matsushita 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 => micron agrees with measured mold pitch of 426/2 micron

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

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

T. Matsushita 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

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

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