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Tracker QAP. Kyberd, M. Takahashi
Quality Assurance for SciFi Tracker(Brunel, FNAL, IC, Osaka)
A status report:
A procedure for ensuring the quality of the finished tracker has been designed following our experience with the construction of the prototype and advice from D0.
The various components of the system have been individually validated, or the problems identified and we have confirmed that suitable solutions exist.
A plan exists to provide a working system in time for the delivery of the fibre doublets and the construction of a fifth station.
The construction of the fifth station will be undertaken at a speed that will allow the QA procedures to be optimised.
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Tracker QAP. Kyberd, M. Takahashi
are collected into bundles of 7 fibres
Fibres run from the doublet layer
20 or 22 bundles are bought into a station connector
Clear fibres run from several station connectors. (internal clear fibres)
Connector to the VLPC cassettes
Problem:
As soon as the fibres are glued into the connectors no further corrections to errors, omissions or faults is possible
External clear fibres
Fibres arrive their properties having been measured at FNAL and Osaka
(Transmission tests for clear fibres and property measurements for scifi using coupons)
Patch Panel
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Tracker QAP. Kyberd, M. Takahashi
Bundles may have too many or two few fibres
Fibres incorrectly positioned in connector
Or fibres may be crossed over
Misalignment between connectors
Clear fibres incorrectly positioned in connector
All fibres susceptible to cracking leading to unacceptable light loss
External clear fibres
Patch Panel
QA Gauge
Objective:
Identify faults before it is too late to correct them OR reject the component before too much time has been spent on it.
Make visual records (photos/videos) at every step
Possible Faults:
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Tracker QAP. Kyberd, M. Takahashi
Assembly Setup:
Carbon-fibre station holder
Bundling Comb - QA
Connectorisation bridge - QA
Vacuum chuck
Alignment jig
OLD
NEW
Change of comb design after the last CM
Doublet layers arrive from FNAL(sample fibres packed with the doublets to act as “telltales”)
Perform QA at each step of the assembly procedure• comb to hold bundles
check bundling and sequence• connectorisation bridge to hold the connectors
check bundle position before potting
Station Assembly and QA(details of the station assembly given at the tracker parallel
session)
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Tracker QAP. Kyberd, M. Takahashi
Count # of fibres under yellow light• fibres visible by eye
– important to keep the fibre ends aligned
• one photo per column (11 bundles) or two columns (one connector)
1 station connector worth of bundles (7 fibres) held together with rubber sleeve, placed in grooves
Check bundling:
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Tracker QAP. Kyberd, M. Takahashi
Mirroring of the fibres prevents injection into the rear of the plane (check again later with the new doublet layers for station 5)
Illuminating the plane will also allow measurement of the light loss from the mirrored end of the fibres
comb
Fibre bundles
Light source(illuminate single fibre or a bundle of fibres)
Cameras
Light leak
Setup for the final scan for bundling:
Identify crossover fibres
Can measure < 5% of the nominal output
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Tracker QAP. Kyberd, M. Takahashi
Scan over the doublet layer using LED • Need to determine which LED (wavelength, intensity,
collimation…) also depends on the UV damage on SciFi (later in the talk)• Optimise CCD (focal length, exposure, comb coverage…)
Ideal to illuminate single fibre to identify any crossover but very difficult especially for the bottom layer
(movie taken with 400nm LED on next slide) We may consider illuminating one bundle at a time
Test Scan:
Will be using a micro-positioning table (brought in from Brunel) for a fully automated scanning
system
potted, cut & polished
held in rubber sleeve (370nm LED)
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Tracker QAP. Kyberd, M. Takahashi
Single Fibre Scan
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5
3
467
First attempt to illuminate single fibre…(400nm LED)
LED
1357
246
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Tracker QAP. Kyberd, M. Takahashi
Fibre bundles
Light source
Camera
connectors on
bridgeScan after placing bundles in connectors
• Check bundle sequence before potting
• Optimum design of bridge will be determined
Sideview
Suitable bend radius
LED
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Tracker QAP. Kyberd, M. Takahashi
Scan film
Prototype station:demonstration of incorrect bundle position identify these faults before potting
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Tracker QAP. Kyberd, M. Takahashi
Wavelength
Currently using 370nm & 400nm LEDs to test QA methods.
D0 have used longer wavelengths
MICE have ordered longer wavelength LEDs and we will use the longest wavelength which gives satisfactory results.
D0 also pulse their UV LEDs and we will implement this if it is necessary
UV damage
UV light damages the scintillation fibre – need to minimise damage and quantify the dangers.
Test
measure the damage and set a limit of 1/10 of a photo-electron for the maximum damage
make sure the total illumination for normal checking is less than 1/5 of this dose
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Tracker QAP. Kyberd, M. Takahashi
Hitachi U4100 sample compartment at Brunel
Measure effect of UV irradiation on the fibres (single or a bundle).
Using high performance photometer
High precision fibre launcher
Status: • Purchased narrow pass filter to absorb scintillation light• Measurements starting presently• A couple of % measurement possible now and <1% later with optimisation • The same setup will be used to check the “telltales” arriving from FNAL with doublets
Detectors & integrating sphere
Aperture
Compartment modified to take optical rails and other components
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Tracker QAP. Kyberd, M. Takahashi
Clear Fibre Waveguides
Fibre runs:
Manufacturer puts the connectors and check the fibre runs will be checked again at Osaka• Injection of LED light done by hand from one end and visual
inspection on the other end (video)• Misplacement of fibres can be corrected in the analysis
Bad Channels:A number of methods exist to identify bad channels(following slides)
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Tracker QAP. Kyberd, M. Takahashi
Methods for finding bad channels(presented by Osaka at pc191)
• 2 kinds of method are applied.Method (1): Taking pictures by a digital camera with flash from the
surface of D0 connector ( or Inner connector). Some bad channels seems shining, which are considered as a reflecting light from bad surface inside the fiber.
Method (2): Looking fibers by eye with injecting light from the connector and finding bad fibers where light is leaking.
• And confirming that bad channels found at (1) and (2) are same or not.
(1) Reflecting light (2) Leaking light
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Tracker QAP. Kyberd, M. Takahashi
Transmission Test (presented by Osaka at pc197)
Rolled
Digital cameraND filter
Green LED
DC Power Supply
Diffuser
~ 20cm~ 20cm
Black Box
Old-type waveguideOld-type waveguide
MICE connector
D0 connector
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Tracker QAP. Kyberd, M. Takahashi
Measured luminosity (presented by Osaka at pc197)
• Right picture shows that channels of small amount of luminosity corresponds to those found by reflecting light check.
• Converting Raw data into ascii file in order to estimate quantitatively. (not yet finished)
Transmission test
#1 #2 #3
#8#9
#10#7#6
#5#4
Reflecting light checkReflecting light check
#10
#7
#6
#5
#4
#1
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Tracker QAP. Kyberd, M. Takahashi
Station Acceptance TestAssembled stations will then be irradiated for a final check
• Co-57 as a radiation source (122keV photons) on XY scanning table
• Full readout chain (VLPC, AFEs)
Measurements will be made on station 4 first
compare with testbeam results for validation
patch panel
to stagecontroller
toVLPC
garage position station holder
XY stage
Light tight box
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Tracker QAP. Kyberd, M. Takahashi
Time Line
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Tracker QAP. Kyberd, M. Takahashi
100% correct fibre runs
Light loss from all sources : bend, cracking, misalignment : < 10%.
Light yield measurements good to better than 10%
Systems will be ready for assembling and testing of the 5th station when the first doublet layers arrive (mid-August).
Steady construction of a station 5 to validate the system.
By end-September the validated QA system will be in place. Ready to start production.
Once the planes have been constructed they will be geometrically characterised with a CMM.
Summary :