tracker qa paul kyberd quality assurance a status report: a procedure for ensuring the quality of...

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


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


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


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)


Picture of scanning system


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


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.


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


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


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?


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


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


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


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.


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.


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


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.


High precision fibre launcher

Light injection


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


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

tracker qa paul kyberd quality assurance a status report: a procedure for ensuring the quality of...

Documents