the work is supported by the hungarian scientific research fund otka t 026178, t034910, t 043145

9 April 2003, J Mocholí Workshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy

Chamber Calibration Bench StatusBarrel MuonAlignment

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Calibration of the position monitoring elements on the Calibration of the position monitoring elements on the barrel muon chambers for the CMS experiment:barrel muon chambers for the CMS experiment:

First experienceFirst experience

The work is supported by The Hungarian Scientific Research Fund OTKA T 026178, T034910, T 043145

The Barrel muon Alignment Collaboration:

Institute of Nuclear Research, ATOMKI, Debrecen, Hungary

European Laboratory for Particle Physics CERN,

Geneva, Switzerland

Institute of Experimental Physics of Debrecen University,Debrecen, Hungary

Institute for High Energy Physics,

Vienna, Austria



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Activities carried out Activities carried out for the period of 24for the period of 24thth Jan to 4th Apr 2003 Jan to 4th Apr 2003

on the Benchon the Bench

ACTION PERFORMED DATE. TIMEBENCH CALIBRATION:

LTD, stability measurement, full bench photogrammetry

24th Jan (stability: Jan 23)

stability measurements January 27,29,31 February 04, 06 Mach 01, 20

Chamber ID:351030100500004 MB2

Photogrammetry

Camera measurement

April 01

April 02 10:32

Chamber ID:351020100900006 MB3 Photogrammetry

Camera measurementsApril 02

April 02. 18:06

Stability measurement April 03. 09:25

Chamber ID:351010100100010 MB1

Photogrammetry

Camera measurements

April 03

April 03. 12:21

Stability measurement April 04. 10:24

Chamber ID:351030100500004 MB2

Photogrammetry

Camera measurements

April 04

April 04. 13:05

The same MB2 chamber(for repeatibility test)



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LTD CalibrationLTD Calibration

Calibration platesequipped with optical fibers



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Chambers on the benchChambers on the bench

MB1

MB2

MB3



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Taking photogrammetry pictures (31 March – 4 April 2003)Taking photogrammetry pictures (31 March – 4 April 2003)

The corner blocks equipped with targets

The plate equippedwith targets



GroupStability measurementsStability measurements

1.Every camera on a plate is facing the LEDs on the opposite plate of the bench.2.Automatic measurement of the centroids of the images of the LEDs on the

opposite side by each camera. 3.The data is recorded in the database with date, time, temperature, amounting to

112 measurements altogether.

Measurement of the stability of the bench:



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Stability measurements: the bench is remarkably stable!Stability measurements: the bench is remarkably stable!DISPLACEMENTS OF A PLATE IN X

198.14

198.16

198.18

198.2

198.22

198.24

198.26

198.28

198.3

1 2 3 4 5 6 7 8 9 10

Measurements along a three months period

X a

vera

ged

( in

pixe

ls)

DISPLACEMENT OF A PLATE IN Y

133.375

133.425

133.475

133.525

133.575

1 2 3 4 5 6 7 8 9 10

Measurements along a three months period

Y a

vera

ged

(in p

ixel

s)

The Bench has shown a remarkable stability along the three month period.

>The displacements in X ~ 0.02 pixel

>The displacements in Y ~ 0.03 pixel

Within the resolution of the measurement

Line 0 plate 1 Line 0 plate 1



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ReflectionsReflections

One LED “ON” on the “6” side

All LEDs “ON” on the “6” side

One LED “ON” on the “4” side

All LEDs “ON” on the “4” side

The camera imageAfter processing:

The correct spot found

The problem is solved.

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Chamber measurement: summary of the first experienceChamber measurement: summary of the first experience

1. Time needed: crane + feet operation: ~2 hours, 4 people needed for the operation. Photogrammetry + camera measurement: 2 hours.

2. Repeatability of a fork installation (repositioning error): within the error of the camera measurement less than about 0.03 pixel.

3. Repeatability of a chamber calibration: the MB2 chamber has been measured twice, the data is still to be analyzed.

5. Several problems have been detected.

4. Repeatability of the positioning of the chamber is OK with the present feet idea (about 1 or 2 mm).



GroupProblems (I)Problems (I)

1. Feet: the principle is OK but a new design is needed to ease the operation (to be discussed). 2. Corner blocks: the hole diameter (nominally L=11 mm Ø8 H7) is often short and/or tight). A temporary solution was found by asking for shorter photogrammetry targets to be made. 3. Pins: In some chambers the pins where the forks are to be fixed are missing.



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Problems (II)Problems (II)

4. Labels:a) Sometimes not readable by the barcode reader.b) Double labels (A and B type) on the same chamber

5. Cabling: The available information is not enough to allow us to define the length of the cable.



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Status - summaryStatus - summary

1. The calibration measurement is done for 1 chamber (out of 250).

2. MB1, MB2 and MB3 chambers have been tested on the bench.

3. The bench is ready to make measurements (stability, camera and photogrammetry and store the data in the database).

4. The analysis program for the reconstruction of the geometry is being finished.

the work is supported by the hungarian scientific research fund otka t 026178, t034910, t 043145

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