November 11 SESAPS 2006 Samir Guragain 1 Calibration, Installation & Commissioning of Sensors for the Alignment of Muon Endcap Chambers in the CMS Experiment S. GURAGAIN, M. HOHLMANN Dept. of Physics, Florida Institute of Technology, Melbourne, FL 32901

November 11 SESAPS 2006 Samir Guragain 2 An Overview Introduction of the system Sensor calibration method and result First commissioning results Summary & conclusion

November 11 SESAPS 2006 Samir Guragain 3 CMS Detector of Magnetic field 4 Tesla The CMS solenoid 13 m long with an inner diameter of 6 m Total weight t The largest superconducting solenoid ever made Overall diameter 15 m 3 Endcap disks and 4 layers on each side. Overall length 21.6 m -Z

November 11 SESAPS 2006 Samir Guragain 4 Transfer plate R-sensors Z-sensors Note: only small sample of analog sensors shown Clinometers Transfer plate DCOPS ME Alignment System The system monitors the positions of Cathode Strip Chambers relative to each other and to the MABs. The alignment uncertainty should be comparable to the chamber resolution and it is defined as 75  m for ME1/2 and 150  m for the others stations.

November 11 SESAPS 2006 Samir Guragain 5 Calibration method & result Linear mover Prec. dowel pins Precision Reference Bar Distance (cm) Typical Z sensor Response (ME1) Sensor Response (V) Results Sensor response vs distance & Ratio of sensor response to ref. Volt vs distance are linear. Slope = V/cm Error in slope = V/cm Acceptable Error Proximity sensor

November 11 SESAPS 2006 Samir Guragain 6 Installation & Commissioning at CERN Cross hair Laser adjustment to pass it through four CCDs in each DCOPS on Straight Line Monitor (SLM)

November 11 SESAPS 2006 Samir Guragain 7 First commissioning results In summer 2006, all the sensors and readout were installed and commissioned on four positive endcap layers. The detector was closed up and the huge 4 T solenoid magnet of CMS was turned on for the first time ever in Aug-Sep, Data during the magnet test phase I & II were logged successfully at different B-field plateaus and have been analyzed.

November 11 SESAPS 2006 Samir Guragain 8 Z sensor data analysis & Results on axial chamber displacement P1 P2 P3 P6 P5 P4 Z1 Finite element analysis predicts a distortion in Z-direction of endcap disks (outer edges) for about 6 mm that is in good agreement with Z1 laser displacement sensor data for upper point 2 but for lower point 5 and 6 the disk bend deformations are less than predicted. Quadratic dependence with magnetic field was observed 6 laser displacement sensors were mounted on theYE+1 disk but only 3 MABs on YB+2. Z B(T) Displacement (mm)

November 11 SESAPS 2006 Samir Guragain 9 Wire extension potentiometer At 4.0 T: The largest displacement between chambers (ME+1 station) does not exceed ~ 700  m Chamber displacement relative to transfer plates at outer edge is small (  m) Displacements between inner/outer chambers: ME+1: neg. sign => disk face compressed ME+2: pos. sign => disk face expanded ME+3: neg. sign => disk face compressed P1 P2 P3 P4 P5 P6 R2 R3 R sensor data analysis & Results on Radial displacement

November 11 SESAPS 2006 Samir Guragain 10 Capacitive fluid level monitor The bending angle for station ME+1 is larger closer to the center (~ 4 mrad) than at the outer edge of the ME+1 disk (~2.5 mrad). Inclinometer data analysis & Results on tilt angle displacement Z-stop Disk Deformation: The current under- standing of yoke disk deformations due to magnetic forces based on these clinometer measurements

November 11 SESAPS 2006 Samir Guragain 11 B (T) Proximity Sensors monitor the distances between the outer ring of muon chambers on station 1. This is the only ring where chambers do not overlap and tracks cannot be used to interpolate between SLMs. Distances between these chambers increased with magnetic field and reached up to 700  m at 4.0T. Azimuthal displacements vs. B: Proximity sensors PX sensor data analysis & Results on azimuthal displacement

November 11 SESAPS 2006 Samir Guragain 12 DCOPS beam profile 2048 pixels per CCD 14 μm pixel pitch 2048 pixels per CCD 14 μm pixel pitch Digital linear CCD-based Optical Position Sensor (DCOPS) with 4×1-d CCDs CCD 2 CCD 4

November 11 SESAPS 2006 Samir Guragain 13 Summary & conclusion About 400 analog sensors were calibrated precisely at Florida Tech and shipped to CERN for the installation. The performance of the sensors up to 4T solenoid magnet during the test was good and they clearly indicated the flexing of the large absorber disks.The results are in good agreement with the finite element analysis predictions. Now half of the system is ready to go into the underground cavern for final position of the detector.