GEM Alignment Z Szillasi On behalf of GEM

GEM Alignment Z. Szillasi On behalf of GEM Alignment group November 15, 2017

The general concept of GEM alignment The aim of the GE-alignment: to locate the strips of the read-out boards in the CMS coordinate system and monitor their movements. The general alignment concept: • • • 9/6/2021 The strips are sealed during the production and not observable. Therefore the strip positions have to be transferred to the observable (outer) part of the chambers during the construction The chamber bodies have to be equipped with the necessary elements for position monitoring. The alignment readout+control should provide the operation of the system. The opto-geometrical data analysis provides the position data. Track-analysis can improve the final accuracy. GEM Alignment 2

Phase II Muon Detector Must be aligned to precision ~ spatial resolution 9/6/2021 GEM Alignment 3

Alignment elements on the chamber - recap Survey target holder (S) Z R-measurement S S R Also sensors between the chambers and the base-plate are considered (z-measurement) 9/6/2021 φ-measurement φ The total number of align. elements per chamber and their locations are still under discussion GEM Alignment 4

Study with simplified model A s the first step a simplified arrangement (see on the picture) has been studied to gin experience with such a system. The „chambers” contain survey targets and a pair of distance sensors on both edges. The model seems to work and converge to correct results. The next step is to describe the real system and substitute the survey measurement by the R and Z measurements. Distance sensors Survey targets The opto-geometrical modelling will give the final answer to the question of the achievable alignment precision and helps to optimize the configurtion of the alignment elements on the chambers (super-chambers). 9/6/2021 GEM Alignment 5

Calibration of the readout boards - 1 Readout board of the long chamber (strips on the back side) R-sensors Phi-sensors Sensors on the readout board of the long chamber p. 6

Fiber Bragg Grating (FBG) Concept TEMPERATURE CHANGE Thermal expansion for Termo-optic effect for STRESS Where: neff is the effective refractive index of the fiber, Λ is the grating pitch and λB is the reflected Bragg wavelength. 9/6/2021 GEM Alignment Elasto-optic effect for Direct Strain for 7

Fiber Bragg Grating (FBG) Concept STRAIN AND TEMPERATURE Sensitivity : FBG Spectral Response (Temperature) FBG SPECTRAL RESPONSE: Temperature Shift Temperature Sensitivity ≈10 pm/°K @ λB=1550 nm 9/6/2021 GEM Alignment T 8

Fiber Bragg Grating (FBG) Concept STRAIN AND TEMPERATURE Sensitivity: FBG Spectral Response (Axial Strain) FBG SPECTRAL RESPONSE: Axial Strain Shift ε Strain Sensitivity ≈1 pm/με @ λB=1550 nm 9/6/2021 GEM Alignment 9

The sensor Two FBGs in a sensor: Optical fiber Glued under tension Strain (S) sensor Glued under tension Temperature (T) sensor Glued with no tension p. 10

Sensor on the readout board 17 mm x 50 mm cutout requested on the GEB for long chambers 9/6/2021 The sensor holder (bracket) glued on the readout board GEM Alignment The sensor fixed to the bracket after the GEB installation 11

MECHANICAL DESIGN 9/6/2021 GEM Alignment 12

LINEAR MOTOR DRIVES & RAILS GEM-PLATE INTERCHANGEABLE BASE-PLATE CAMERA LINEAR MAGNETIC ENCODER LINEAR GUIDE 9/6/2021 GEM Alignment OPTICAL TABLE 13

POSITIONONG BRACKET 9/6/2021 GEM Alignment 14

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Positioning Bracket Reference point 9/6/2021 GEM Alignment 16

Reference point of Sensor Reference Edge Bracket 9/6/2021 GEM Alignment 17

Measuring and technological order 1. Determination of the inner reference points from the outers with coordinate measuring system. (Calibration of the base plate) 2. Optometric check of the base plate with the designed measuring and bonding system. 3. Fixation of sensor brackets onto the base plate 4. GEM plate bonding to brackets 5. Determination of the position of strips from the outer references with optometric method. 6. Calculation of the positions of strips from the bracket’s references 9/6/2021 GEM Alignment 3 4 2 1 18

Scanning table in the lab 9/6/2021 GEM Alignment 19

Displacement Sensor Force(N) d. Y Fiber sensor Fixed side d. X 9/6/2021 GEM Alignment 20

Displacement Sensors 9/6/2021 GEM Alignment 21

Displacement sensor Force Spring Sensor Head 9/6/2021 GEM Alignment 22

Displacement Sensor 9/6/2021 GEM Alignment 23

Displacement Sensor 9/6/2021 GEM Alignment 24

Displacement Sensor 9/6/2021 GEM Alignment 25

SLICE TEST CHAMBER 9/6/2021 GEM Alignment 26

Sensor – finite element analysis 5 mm here 20 micrometer here 9/6/2021 GEM Alignment 27

Slice test chamber with Alignment sensors Alignment sensor body without spring (for reference measurement) ST 2 Alignment sensor bracket for R sensor ST 1 ST 3 9/6/2021 Alignment sensor body with spring GEM Alignment ST 4 28

Slice test chamber in CMS • Chamber name where the alignment sensor is installed: – – – • This chamber is installed on position YE-1 GE 1/1/28 • • SCL-01 super chamber Barcode on patch panel: GE 1/1 -SCL-001 / 306300011000001 Name on chimney: GEII-VII-L-CERN 0002 (Top chamber) Continuous data taking and monitoring of the peaks during sensor installation on chamber and also before and after the installation of the chamber in P 5. As soon as the final optical cable installed the chamber connected to the FOS readout optical system. Since then it is included in the FOS DCS system. 9/6/2021 GEM Alignment Each peak on this spectrum represents either a strain (distance) sensor or a temperature compensator sensor 29

Sensor behaviors during the first magnet ramp up 2017. 05 -07 sensor response vs. magnetic field sensors are not calibrated! 2017. 05. 06. ST 3 S and ST 4 S are the strain sensor part and they equipped with spring and the temperature change is compensated 2017. 05. 07. 2017. 05. 08. ST 3 S sensor show correlation with magnetic field while ST 4 S not very much ST 3 S and ST 4 S show correlation something witch is induced by a temperature change (see next slides) 9/6/2021 GEM Alignment 30

Sensor behaviors during the first magnet ramp up 2017. 05. sensor response vs. magnetic field sensors are not calibrated! ST 3 S and ST 4 S are the strain sensor part and they equipped with spring and the temperature change is compensated 2017. 05. 06. Magnified view, clear correlation of ST 3 S with magnetic field 9/6/2021 GEM Alignment 31

Sensor behaviors during the first magnet ramp up 2017. 05 -07 sensor response vs. LV VFAT status sensors are not calibrated! ST 3 S and ST 4 S are the strain sensor part and they equipped with spring and the temperature change is compensated LV VFAT ON Magnetic field is stable in this period ~0. 1 nm LV VFAT OFF 2017. 05. 06. 2017. 05. 07. ST 3 S and ST 4 S sensors show correlation with the LV switch on of the chamber heat dilatational movement between chambers This is Δλ = ~0. 1 nm 9/6/2021 GEM Alignment 32

ST 3 S sensor delta 0 T vs 3. 8 T (LV ON) comparison sensors are not calibrated! ST 3 S and ST 4 S are the strain sensor part and they equipped with spring and the temperature change is compensated ~0. 1 nm 2017. 05. 06. 2017. 05. 07. 2017. 05. 08. ST 3 S sensor response to magnetic field: Δλ = ~0. 1 nm 9/6/2021 GEM Alignment 33

Observed movements of the chambers Chambers fixation is a pin in a rail in inner R ST 3 magnetic field response heat dilatation of the chambers X ST 4 Chambers fixed with screw in outer R 9/6/2021 GEM Alignment 34