# Presentation: 234064

## Results of EMU Alignment Test June-Sept 2000 at CERN ISR Tunnel

**Goal :****  **
- Setup the EMU alignment prototype, take data, analyze data, and compare the reconstructed positions with the surveyed positions.
- The goal is to achieve an order of 200 m resolutions.
- Demonstrate System Redundancy       (stability and reproduciblity).
**Test Setup :**
- 1 SLM Line (2 lasers, one from each end)
- 1 Transfer Line (one laser)
- 1 Transfer Plate
- Analog Sensors (Temp, Proximity)
**Analysis :**
- 1500+ Events Reconstructed

**Results of EMU Alignment Test** ***June-Sept 2000 at CERN ISR Tunnel***

- EMU Meeting, UCLA
- March 24, 2001
- Kaori Maeshima (FNAL)

## Prototype Test SetupJune-Sept 2000 at CERN ISR Tunnel

- Assumptions :
-   Sensors et2, et3, and es10 are known
-   Transfer Plate definition is defined
-   Rotations of sensors are known within error
-     limits of photogrammetry

- Prototype Test Setup***June-Sept 2000 at CERN ISR Tunnel***

## RAW CCD Centroids

- _RAW CCD Centroids_

- typical Laser signal profiles (es6, L303)

- fitted centroid positions vs. time (es6, L303)
- Over a few days period, sigma(rms) is order of 1 pixel (= 14 m)

## Fitting Procedure:Signal(gaussian) + Background

- CCD Peaks in es9 from laser 302 ...

- CCD Peaks in es9 from laser 303 taken *immediately* after laser 302 data...

- Background shape depends on the signal.
- Simple signal fitting after subtracting background (laser off data) does not work.

## COCOA Reconstruction Stability(ISR Test Results – es9 Reconstruction)

- Sample September Laser 302 Results (1 sensor)

- Sample September Laser 303 Results (1 sensor)

**COCOA Reconstruction Stability***(ISR Test Results – es9 Reconstruction)*

## Laser Jumping andIndependence in Reconstruction

**Distribution of raw CCD means in es4 during the July/August Run.  Jump of 30 pixels = 420********m **** **

**Distribution of COCOA Reconstructed location of es4 in the ISR hall during the July/August Run.**** (********y**** = 10 ********m, ********z**** = 8 ********m)**** **

*Conclusion : Shift in Laser not seen in Reconstruction*

- 30 pixels

**Laser Jumping and****Independence in Reconstruction**

## COCOA Reconstruction Results(ISR Test Results – es10 Reference)

**SLM  Line (Laser 302) Results of COCOA Reconstruction for **
**July/August and September Runs** **Using es10 as the Final **
**Reference Sensor**

**SLM  Line (Laser 303) Results of COCOA Reconstruction for **
**July/August and September Runs** **Using es10 as the Final **
**Reference Sensor**

**COCOA Reconstruction Results***(ISR Test Results – es10 Reference)*

## COCOA Reconstruction Results(ISR Test Results – es9 Reconstruction)

**SLM  Line (Laser 302) Results of COCOA Reconstruction for **
**July/August and September Runs** **Using es9 as the Final **
**Reference Sensor**

**SLM  Line (Laser 303) Results of COCOA Reconstruction for **
**July/August and September Runs** **Using es9 as the Final **
**Reference Sensor**

**COCOA Reconstruction Results***(ISR Test Results – es9 Reconstruction)*

## COCOA Reconstruction Results(ISR Results – es9,  March 2001 Analysis)

**SLM  Line (Laser 302) Results of COCOA Reconstruction for July/August and September Runs** **Using es9 as the Final Reference Sensor**

**SLM  Line (Laser 303) Results of COCOA Reconstruction for July/August and September Runs** **Using es9 as the Final Reference Sensor**

**COCOA Reconstruction Results***(ISR Results – es9,  March 2001 Analysis)*

## Results The Bottom Line (March 2001)

- We have demonstrated reconstruction of sensor positions within 200-300 m of CERN PG.
- The measurements results are stable and show consistency between july/sept & L302/L303 data within the expected uncertainties.
- Real CMS data can be better than March 2001 Results:
- 3 CCDs only on Reference Sensors
- 	(4 CCDs improve results)
- Calibration Errors larger than expected, no calibration prior to installation
- 	(better results with better calibration)
- More Constraints on COCOA Fits
-     (Calibrated X-Hair Laser, Inclinometer
-  	  Data on Transfer Plate)

## ResultsGeneral Remarks

- Large survey errors
- 60 m local  120 m global
- ~ 180 m Systematic Errors
- < 15 m Statistical Errors
**General Conclusions :****  **
- _4 CCD measurements on reference Sensors are critical_
- Reconstruction is roughly independent of laser choice (within error)
- Reconstruction is independent of laser motions.

**Results***General Remarks*

**From the CERN Alignment workshop (March, 2001), it was concluded that we continue to use and farther develop  **
**COCOA simulation software**** (Link+EMU). **
**Robert Lee and Pedro Arce have been working jointly in COCOA.**

## COCOA Reconstruction ResultsThoughts on COCOA

- Comparison of COCOA Results to ‘Hand Calculations’
- We have verified operation in simple EMU type systems to < 100 m
- We cannot verify in ISR EMU system to <400 m (rotations, calibration errors, transfer plate errors)
- Evidence of COCOA Accuracy
- Prediction of et3 dowel location direct from PG agrees within 10 m from CERN PG group determination
- Prediction of et1-es1 separation on Transfer Plate within 30 m of CMM determination (full EMU simulation)
- Concerns
- Convergence of fit to local minima (false solutions)
- Degenerate rotations possible