CMS Tracker Hardware Alignment A Ostaptchouk RWTHAachen Goals

CMS Tracker Hardware Alignment A. Ostaptchouk, RWTH-Aachen Goals of TK hardware alignment Concept General layout Internal TK alignment External TK alignment (LINK) Hardware Conclusions 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki

Goals of Hardware Alignment External alignment: 100 m measurement of TK position w. r. t. MS 20 rad measurement of TK orientation w. r. t. gravity both for joint TK+MS track fit Internal alignment: 100 m measurement of Si-module relative positions for track pattern recognition (recent H. Voss and B. Schwering results: 1000 m ! t. b. c. ) 10 m monitoring of Si-module positions stability for track parameter reconstruction 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 2

Concept of Hardware Alignment 1. No dedicated optical sensors Collimated laser beams with ~ 1060 nm produce signals directly in the TK Si-modules 2. No external reference structures All the elements of the alignment system are mounted directly on the TK parts 3. No precise positioning or aiming of beam collimators Number of measurements redundant enough to reconstruct detector positions without knowledge of laser beam initial parameters 4. Minimal impact on the TK layout and production technology The effected tracker parts are as uniform as possible 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 3

General Layout of Alignment System External alignment: six Ray 1 beams per TEC align TK w. r. t. MS Internal alignment: eight Ray 2 and eight Ray 3 beams per TEC align forward wheels, monitor 50% of petals eight Ray 4 beams align end-caps and barrels w. r. t. each other 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 4

Internal Alignment Implementation Laser beams through End-Caps holes in supports (petals, wheels) holes in back-side metallisation of Si-sensors (2500/24000) Laser beams through Barrels structure gaps in TOB inner shell alignment tubes inside these gaps fixed on TOB support discs 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 5

Internal Alignment Simulation Track residuals in End-Caps TEC: before applying alignment corrections RMS = 1. 1 mm TEC: after applying alignment corrections RMS = 27 m Track residuals in Barrels TOB: after applying alignment corrections RMS = 49 m TIB: after applying alignment corrections RMS = 85 m 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 6

External Alignment Concept of External Alignment System position of TK w. r. t. MS is determined by precise measurement of continuous laser beam positions inside TK and MS (LINK) On TK side it requires: 2 D-sensors on TEC petals periscopes inside TEC back-disc orientation of TK w. r. t. gravity is determined by precise measurement of TEC back-disc orientation w. r. t. TEC wheels and gravity It requires back-disc instrumentation with Si-modules at radius of ray 2 and tiltmeters 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 7

External Alignment Elements Instrumented TEC back-disc Periscope mounted inside TEC back-disc 2 D-sensor made of two Si-modules 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 8

External Alignment Simulation TK-MSpos - precision of TK position w. r. t. MS is defined by measurements of 6 laser beams (ray #1) inside the TK volume: • r -positions of laser beams w. r. t. TK • r 20 m • -orientations of laser beams w. r. t. TK • 20 rad (characteristic distance between TK and MS L 5 m) TK-Gori - precision of TK orientation w. r. t. gravity is determined by two independent factors: • back-disc orientation w. r. t. TEC (measured by 8 laser beams, ray #2) • BD-TEC 10 rad • back-disc orientation w. r. t. gravity (measured by 4 tiltmeters, requires their calibration w. r. t. back-disc fiducials) • BD-G 10 rad 1 June 2002 pos TK-MS ori TK-G Workshop on b/tau Physics at LHC, Helsinki = r L 100 m = BD-TEC BD-G 20 rad 9

Hardware: Experience from AMS-1 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 10

Hardware: Experience from AMS-1 Si-module transparency (@ = 1064 nm) is about 20 – 25 % Beam spot position resolution is better than 10 m 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 11

Hardware 1 D Si-Modules (Ray 2&3) 1 D Si-modules for Ray 2&3 are the standard Si-modules of the TEC Rings 6&4 (both sides polished plus hole) 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 12

Status of LINK Elements 2 D Si-Modules (Ray 1) 2 D Si-modules are made out of two standard Si-modules from Ring 1 & Ring 2 (wafers W 1 & W 2) 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 13

Hardware Optical Wafers Production of optical wafers: Table of optical wafers Wafer type Total number of TEC wafers (+5% cont) Additional alignment wafers Specially treated wafers Comments W 6 b 1008 (50) 18 140 Hole 10 mm Both sides polished W 6 a 1008 (50) 18 0 W 4 1008 (50) 0 420 Hole 10 mm Both sides polished W 2 576 (29) 30 30 Hole 28 mm Both sides polished W 1 288 (14) LINK wafers 1 June 2002 30 30 ______ Hole 28 mm Both sides polished Additional alignment wafers are included to the general order for Hamamatsu The company will polish their both sides and will produce holes in metallisation Prototypes will be delievered in July 2002 If they are OK (transparency, electrical properties), all the optical wafers – in Fall 2002 Internal alignment wafers Workshop on b/tau Physics at LHC, Helsinki 14

Status of LINK Elements Periscope mounting scheme: 3 very hard balls 2 CFC platforms 3 hardened Al inserts 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 15

Status of LINK Elements Periscopes Two options for the periscope design: Hollow CFC body with mirrors glued on it (Aachen) Single piece of quartz with mirror coated edges (Spain) Requirements for the periscope mounting/housing: Reproducibility: position 20 m orientation 100 rad Cold-warm transition: inside TK volume -10 o C outside TK volume +20 o C 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 16

Status of LINK Elements Tiltmeters Current choice: Wendor: Serie: Total range: Resolution: Repetability: Environmental: Sensors: Dimensions: 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki Applied Geomechanics 756 (Mid-Range) 10 degrees 1 rad 2 rad -25 o C to +70 o C, 0 to 100% hum. 2 tilt , 1 temp 41 x 51 x 25 mm 3 17

Test Plans Test of Optical Si-Modules Stage Responsibl e Date Hamamats u Sep 2002 Alignment Bonding, mechanical modules & electronical assembly Aachen Nov 2002 Laborator Transmittion, reflectio y n, tests resolution Aachen May 2003 Beam tests DAQ, combined particle & optics data analysis Aachen Oct 2003 Optical wafers 1 June 2002 Comments Both sides polished Hole in metallisation Workshop on b/tau Physics at LHC, Helsinki 18

Test Plans Test of Periscopes Stage Comments Responsible Date Prototype option I Hollow CFC body with two mirrors glued Aachen Islamabad March 2002 Prototype option II Solid transparent body with two edges coated Spain 2002 Mounting platforms Suitable for both options Aachen Summer 2002 Tests Cold-warm transition, 4 sensors, support Aachen Spain Spring 2003 Periscopes calibration Phogrammetry method CERN facility Spain Aachen Summer 2003 1 June 2002 Workshop on b/tau Physics at LHC, Helsinki 19