tracker qa p. kyberd, m. takahashi 1 quality assurance for scifi tracker (brunel, fnal, ic, osaka) a...

1

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.

2


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

3


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:

4


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)

5


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:

6


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

7


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)

8


Single Fibre Scan

12

5

3

467

First attempt to illuminate single fibre…(400nm LED)

LED

1357

246

9


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

10


Scan film

Prototype station:demonstration of incorrect bundle position identify these faults before potting

11


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

12


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

13


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)

14


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

15


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

16


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

17


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

18


Time Line

19


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 :

tracker qa p. kyberd, m. takahashi 1 quality assurance for scifi tracker (brunel, fnal, ic, osaka) a...

Documents