Tracker QAPaul Kyberd
Quality Assurance
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 is being undertaken at a speed that will allow the QA procedures to be optimised.
The final procedure will have been defined by the collaboration meeting at RAL
Tracker QAPaul Kyberd
are collected into bundles of seven
Fibres run from the doublet layer
20 or 21 bundles are bought into a station connector
Clear fibres run from several station connectors to
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
Tracker QAPaul Kyberd
Bundles may have too many or two few fibres
Fibres incorrectly positioned in connector
Incorrect positioning of the fibres to the VLPC not part of tracker QA
Possible Faults:
Or fibres may be crossed over
Misalignment between connectors
Clear fibres incorrectly positioned in connector
Misalignment between connectors
All fibres susceptible to cracking leading to unacceptable light loss
Tracker QAPaul Kyberd
Objective:
Identify faults before it is too late to correct them OR reject the component before too much time has been spent on it.
Method: Inject light.and track its pathSilvering of the fibres prevents straightforward injection into the rear of the plane
Solution illuminate the plane with a UV LED
Picture of fibre fluorescing
Picture of illumination system
Question of damage to the scintillator
(considered later)
Tracker QAPaul Kyberd
Picture of scanning system
Tracker QAPaul Kyberd
Bundle fibres up into sevens – do about 10 bundles.
Illuminate
Picture of comb
Hold the fibres together with a rubber sleeve (already used to make the prototype. Place the bundles in a “comb” to hold them together and in place
For these pictures 370nm was used throughout
Tracker QAPaul Kyberd
Bundle fibres up into sevens – do about 10 bundles.
Illuminate
Clearly observe the twoLayers
Counting seven is easy
Unfibre and repeat ifproblems
Number determined by experiment – to minimise the total construction time.
it takes n minutes to make a bundle we check every G bundles which takes a time of (G*m + s) minutes.
If the probability of making a mistake is p% (known empirically to be <1%). Total time for a plane is
~ [G*n + (G*m + s) + p*(G+1)*n/2]*T/G
with T bundles per plane.
Tracker QAPaul Kyberd
A
B
A BIntegral Integral
26326 4853845327 49872NA 3919748720435964890725881 Centre 45559
Circle radius of 12 pixels used, Integral intensity in arbitrary units. Background “black” is effectively 0 Automatic Measurement:
An astronomical program confirmed
• we can identify individual fibres
• we can measure their light output
In this picture no attempt was made to control the illumination
Tracker QAPaul Kyberd
Final scan:
Final scan to check
Second camera is looking at rear of fibres for excessive light leaks.
Can measure < 5% of the nominal output
Tracker QAPaul Kyberd
Scan after placing bundles in connectors
Frame mounted to take connectors and bundles placed in the correct place in each connector
Scan across the full plane to check that bundles are correctly placed in connectors
Does Geoff have an drawings of this?
Tracker QAPaul Kyberd
Status:
All fibres in their correct bundle
All bundles in their correct station connector
Ideally we would also check light out put at this stage but until the fibres are glued into the connectors and the ends polished a reliable measurement of the light output is not possible
Silvering OK
Tracker QAPaul Kyberd
Light Output:
Picture of glued and polished system
At this`stage we measure light output.
We will also make this measurement on the old stations which have been disassembled – this will allow us to validate the UV measurements against the test beam results
Tracker QAPaul Kyberd
Check “wiring” of clear fibre runs
Picture of clear fibre bundles and the connectors at each end Inject red light and measure output
fibre.
Injection done in order by hand – photographs taken of the output and the two cross correlated subsequently.
The experimenter will record the input connector/fibre number, the programme will determine the “correct” input connector/fibre number from the output fibre number.
The experimenter will not be able to influence the comparison in order to combat the “see what you expect” effect
Tracker QAPaul Kyberd
Final check
Connect up final station and scan checking light output at the end of the clear fibre run
This is a final cross check and is not strictly necessary. Given that the fibres of the two other views will also receive a UV dose this measurement will only be made if the safety margin on the damage is significant.
Tracker QAPaul Kyberd
Charged particle tests
The station will then be irradiated by a …. Source to check response to charged particles.
Any variation of light output observed at this stage can be referred back to the UV measurements and the discriminating power of the method determined.
Ken - do you want this covered in QA?– if so do we have any drawings/pictures or other information which should be included.
These measurements will also made on existing stations and the test beam results used to validate the measurements.
Tracker QAPaul Kyberd
Wavelength
Currently using 370nm LEDs which give good results.
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
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
Tracker QAPaul Kyberd
Compartment modified to take optical rails and other components
Aperture
Detectors & integrating sphere
Hitachi U4100 sample compartment
Measure effect of UV irradiation on the fibres.
Tracker QAPaul Kyberd
High precision fibre launcher
Light injection
Tracker QAPaul Kyberd
April 24 - May5 Determine UV wavelength
May 1 –May11 Measure UV damage for 3 wavelengths
1st Week June Ship scanning table to IC from Brunel
???? Delivery of comb from Liverpool
???? Fibre table ready (including connector holders)
???? Ship old plane from Brunel (same as comb delivery)
???? Check of fibre procedure
April 24 – June 26 Complete test rig software
June 26 – July 7 Assemble the old plane and verify the procedure
Tracker QAPaul Kyberd
System to be ready by end June for the delivery of the first doublet layers.
Slow construction of a plane to shake down the system and sort out any problems.
By the September collaboration meeting - the final QA system will be in place. Ready to start production
April 24 - May5 Determine UV wavelength
May 1 –May11 Measure UV damage for 3 wavelengths
1st Week June Ship scanning table to IC from Brunel
???? Delivery of comb from Liverpool
???? Fibring table ready