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

Calibration of the position monitoring elements on the barrel muon chambers for the CMS experiment: First experience. The Barrel muon Alignment Collaboration:. Institute of Nuclear Research, ATOMKI, Debrecen, Hungary European Laboratory for Particle Physics CERN, Geneva, Switzerland

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

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  1. Calibration of the position monitoring elements on the barrel muon chambers for the CMS experiment:First experience The Barrel muon Alignment Collaboration: Institute of Nuclear Research, ATOMKI, Debrecen, Hungary European Laboratory for Particle Physics CERN, Geneva, Switzerland Institute of Experimental Physicsof Debrecen University, Debrecen, Hungary Institute for High Energy Physics, Vienna, Austria The work is supported by The Hungarian Scientific Research Fund OTKA T 026178, T034910, T 043145

  2. Activities carried out for the period of 24th Jan to 4th Apr 2003 on the Bench The same MB2 chamber (for repeatibility test)

  3. LTD Calibration Calibration plates equipped with optical fibers

  4. Chambers on the bench MB1 MB3 MB2

  5. Taking photogrammetry pictures (31 March – 4 April 2003) The plate equipped with targets The corner blocks equipped with targets

  6. Stability measurements Measurement of the stability of the bench: 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.

  7. Stability measurements: the bench is remarkably stable! Line 0 plate 1 Line 0 plate 1 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

  8. Reflections After processing: The correct spot found The camera image  All LEDs “ON” on the “6” side One LED “ON” on the “6” side All LEDs “ON” on the “4” side One LED “ON” on the “4” side The problem is solved.

  9. Chamber 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. 4. Repeatability of the positioning of the chamber is OK with the present feet idea (about 1 or 2 mm). 5. Several problems have been detected.

  10. 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.

  11. 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.

  12. Status - 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.

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