J.-C

. Bar

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ePRAXIAL ALIGNMENT SYSTEM (barrel)

posi

tion

ing

cali

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ion

calibration of PRAXIAL part

ATLAS Align. PDRJ.C. Barrière (Saclay)

calibration of AXIAL part

PRAXIAL activeoptical elements

Platform positioning duringMDT construction

Tool for the platformpositioning

QA/QC: in production site and at the CERN X-ray tomograph

conclusion

Top view

PRAXIAL ALIGNMENT SYSTEM Principle

The PRAXIAL system is used to unite a layer of chambers (about 6 MDT) to form a single “rigid” layer. It is composed by two systems:

the axial system (overlapping Rasniks // to beam axis – z –),the proximity system (2 short crossed Rasniks).

The requirements for the axial are: ±5 m, for the proximity system: ±5 m and ±30 rad.

The precision on the positioning of both systems are: ± 25 m

3D view

Top viewaxial Rasnik

axial Rasnik

2 proximity Rasniks

MDT chambers

Reference system

Toroid rib

ATLAS Align. PDRJ.C. Barriere (Saclay)

X

Z

Atlas axis

MDT- n MDT- n+1

installation of PRAXIAL platforms(on each production site)

calibration of the PRAXIAL

positioning tools

J.-C

h. B

arri

ère

PRAXIAL ALIGNMENT SYSTEM (barrel)po

siti

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gca

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Calibration of PRAXIAL part

final QA/QC with the CERN X-ray tomograph

ATLAS Align. PDRJ.C. Barrière (Saclay)

calibration of AXIAL part

Principle

PRAXIAL ALIGNMENT SYSTEM Caliprax

ATLAS Align. PDRJ.C. Barrière (Saclay)

HARDWARE:•6 axis motorised table with end-switches,

range ± 5 mm, ± 10 mrad.•stiff mechanical structure,•displacement sensors (rasnik/linear encoders)

= 1µm,•temperature probes,•1 PC computer for control and calibration.

SOFTWARE:•ICARAS (rasnik readout),•MINUIT routines (fit),•C++ (general program).

ACCURACY•± 5 µm,•± 30 µrad.

PRAXIAL ALIGNMENT SYSTEM Calibration of proximity part.

ATLAS Align. PDRJ.C. Barrière (Saclay)

A u tom atic ca lib ra tionO p tion 1

G eom etrica l recon s tru c tion :3 0 /3 6 p aram eters

A u tom atic ca lib ra tionO p tion 2

lin ear ap p roxim ationTran s fe rt m atrix: 4 8 p aram eters

Z erop raxM ech an ica l b en ch (m arb le tab le ) a t

th e n om in a l p os it ion

2

2

2

2

1

1

1

1

matrix tansfert : T

Yccd

Xccd

Yccd

Xccd

Z

Y

X

dZ

dY

dX

Z

Y

X

Z

Y

X

Z

Y

X

Masks & CCD:

Lenses:

2

2

2

2

1

1

1

1

Yccd

Xccd

Yccd

Xccd

1 movement: 2*4 known parameters

1 movement: 6 know parameters

Zd

Yd

Xd

dZ

dY

dX

8N > 36N: number of measurements

Known withlinear encoders Measured with

praxial rasniks

At least 66 movements

PRAXIAL ALIGNMENT SYSTEM Manual calibration.

ATLAS Align. PDRJ.C. Barrière (Saclay)

1st step: 40 movements for calibration.

2 nd step: 140 movements:55 pure movements95 combined movements.

installation of PRAXIAL platforms(on each production site)

calibration of the PRAXIAL

positioning tools

J.-C

h. B

arri

ère

PRAXIAL ALIGNMENT SYSTEM (barrel)po

siti

onin

gca

libr

atio

n

Calibration of PRAXIAL part

final QA/QC with the CERN X-ray tomograph

ATLAS Align. PDRJ.C. Barrière (Saclay)

Calibration of AXIAL part

Principle

ATLAS Align. PDRJ.C. Barrière (Saclay) PRAXIAL ALIGNMENT SYSTEM

Calibration of axial part.

1st STEP (manual operation):

Calibration of 3 cubes containing Rasnik elements (mask, Lens, CCD)

7 measurements (X, Y, & ) to control the position of the rasnik elements in the cubes and the bench geometry.

2nd STEP:

Calibration of the axial elements.One of the cubes is replaced by the axial element to be calibrated.

1 measurement/ axial optical element5 m long marble

2x

ATLAS Align. PDRJ.C. Barrière (Saclay) PRAXIAL ALIGNMENT SYSTEM

Conclusion: status & schedule.

PROXIMITY CALIBRATION (2*1250 units, 6 different gaps):

Status: 6 axis motorised tables, endswitches, linear sensors are available. Software is under construction. Mechanical structure is studiedSchedule: first calibration in september 2001.

AXIAL CALIBRATION:

Status: principle of the calibraton has already been tested.Sofware exists and has to be adapted. Schedule: first calibration at end of 2001.

POSITIONNING & CONTROL TOOLS:

The tools are now understood (4*6 positioning tools delivered + control towers). Many error sources are possible.Differential sag between tubes and wires has to be checked.Next X-tomo control end of april 2001 (4 masks delivered).

Chambers A or C Sectors17,5 18,1 18,3 18,6 18,8 18,9 19 19,8 32,2 32,8 32,9 33 50,5 198,8 343,3 388,3 452* 489* 1266,4* 1302,4*

BIS Standard (x16) 1 5BIL Standard (x10) 3 1 1BIL S13 (x2) 2 2 1BIM S11 or 15 (x4) 4 1BIR S11 or 15 (x4) 1 1 1 1 1 1

BMS Standard (x12) 1 1 1 1 1BML Standard (x16) 3 2BMF S12 or 14 (x4) 1 1BOS Standard (x12) 5BOL Standard (x12) 4 1BOF S12 or 14 (x4) 5 3

Total (all sectors) 108 72 12 32 66 12 98 10 24 4 4 4 12 2 12 12 4 4 4 4

Distances between chambers (mm)

Chambers A or C Sectors17,5 18,1 18,3 18,6 18,8 18,9 19 19,8 32,2 32,8 32,9 33 50,5 198,8 343,3 388,3 452* 489* 1266,4* 1302,4*

BIS Standard (x16) 1 5BIL Standard (x10) 3 1 1BIL S13 (x2) 2 2 1BIM S11 or 15 (x4) 4 1BIR S11 or 15 (x4) 1 1 1 1 1 1

BMS Standard (x12) 1 1 1 1 1BML Standard (x16) 3 2BMF S12 or 14 (x4) 1 1BOS Standard (x12) 5BOL Standard (x12) 4 1BOF S12 or 14 (x4) 5 3

Total (all sectors) 108 72 12 32 66 12 98 10 24 4 4 4 12 2 12 12 4 4 4 4

Distances between chambers (mm)