Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 1 Calibration of the position monitoring elements on the barrel muon chambers for the CMS experiment: First experience The work is supported by The Hungarian Scientific Research Fund OTKA T , T034910, T 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

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 2 Activities carried out for the period of 24 th Jan to 4th Apr 2003 on the Bench ACTION PERFORMEDDATE. TIME BENCH CALIBRATION: LTD, stability measurement, full bench photogrammetry 24 th Jan (stability: Jan 23) stability measurementsJanuary 27,29,31 February 04, 06 Mach 01, 20 Chamber ID: MB2 Photogrammetry Camera measurement April 01 April 02 10:32 Chamber ID: MB3 Photogrammetry Camera measurements April 02 April :06 Stability measurementApril :25 Chamber ID: MB1 Photogrammetry Camera measurements April 03 April :21 Stability measurementApril :24 Chamber ID: MB2 Photogrammetry Camera measurements April 04 April :05 The same MB2 chamber (for repeatibility test)

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 3 LTD Calibration Calibration plates equipped with optical fibers

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 4 Chambers on the bench MB1 MB2 MB3

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 5 Taking photogrammetry pictures (31 March – 4 April 2003) The corner blocks equipped with targets The plate equipped with targets

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 6 Stability 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:

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 7 Stability measurements: the bench is remarkably stable! 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

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 8 Reflections 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 image After processing: The correct spot found The problem is solved.

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 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. 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).

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 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.

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 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.

Chamber Calibration Bench Status Barrel Muon Alignment Group 9 April 2003, J MocholíWorkshop on "LHC Physics with High-Pt Muons in CMS'‘, Bologna, Italy Page 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.