Calibration of Analog Calibration of Analog Sensors for the Alignment Sensors for the Alignment of Muon Chambers in the of Muon Chambers in the

CMS experimentCMS experiment

Marion Ripert, Georgia Karagiorgi, Thomas Moschoutis Dr. L. Caraway, Dr. M. Hohlmann

Department of Physics and Space SciencesFlorida Institute of technology

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

LLargearge H Hadron adron CColliderollider

• pp machine (mainly) 7 Times higher than energy in the Tevatron at Fermilab.

•Bunches of protons collide in CMS every 25 ns

s = 14 TeV

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Endcap disks

Outer barrel rings

Central barrel ring

The CMS solenoid will be 13m long with an inner

diameter of 6m – the largest superconducting

solenoid ever made!

The Muon DetectorThe Muon Detector

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Installation of muon Installation of muon chambers on ME+2 endcap chambers on ME+2 endcap

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

R – SensorR – Sensor

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Z - SensorZ - SensorLinear motion potentiometer

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Clinometer

R-sensorsZ -sensor

Calibration of R , Z Calibration of R , Z sensors and clinometerssensors and clinometers

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Recent ActivitiesRecent Activities

• Calibration Bench finished for R sensors, Z sensors, and Clinometers

• Understanding & reducing uncertainties:

-Reference bar accuracies-Mechanical Tolerance on dowel holes &

pins-Mounting procedures

• Calibrating production sensors for ME+3

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Line Up Reference pointsLine Up Reference points

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

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Sen

sor R

espo

nse

(V)

313029282726Distance (cm)

Plate ME+2/2/3-HV-OR with R-sensor R2TP1sens-22_03>OUTSensor Response vs. Distance

(5 out of 30 trials shown)

• remove plate from stand• reestablish initial absolute distance with R-bar• remount plate • remeasure

Results for R-sensorsResults for R-sensors:

Mean Fit line (30 measurements): y(x) = -51.3923 + 2.00482x σ(slope) = rms = 0.00047σ(Y-intercept) = rms = 0.0314

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

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FR

EQ

2.0522.0512.0502.0492.0482.0472.0462.0452.0442.0432.0422.0412.040SLOPE (V/cm)

Test1 : Histogram of 30 measurements of the slope (V/cm) of the linear curve ( Sensor Resonse (V) vs distance (cm)) of the extension of the R sensors ( LX-PA-2 S/N 3310410;PLATE me+2/2/8-AN-OR) with old holes.

mean: 2.04529 V/cmrms : 0.00166V/cm

Measuring relative changes in Measuring relative changes in distancesdistances

<slope> = 2.0453 ±0.0003 (stat) V/cm

0.015%slope

) slopeσ(

Corresponds to σΔx = 8 μm over full range (50 mm)

5 calibration measurementsper sensor will be sufficient toachieve σΔx = 20 μm over 50mm

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Measuring absolute distances : need new Measuring absolute distances : need new dowel holes.dowel holes.

V061.0)intcpt( holesdoweloftolerancewithproblemm 300)x(

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Fre

q

-47.60 -47.55 -47.50 -47.45 -47.40 -47.35 -47.30 -47.25 -47.20 -47.15 -47.10Y-intercept (V)

Test1: Histogram of 30 measurements of the Y-intercept (Volts) of the linear curve ( sensor response (Volts) vs Distance (cm)) of the extension of the R-sensors ( LX-PA-2 S/N 3310410;plate ME+2/2/8-AN-OR) with old holes.

Hist : mean = -47.311V; rms = 0.0609 V G-FIT:mean = -47.278V;sigma = 0.0682V;

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Checking the Calibration methodChecking the Calibration method : : No dismounting and remounting of No dismounting and remounting of

plates between measurementplates between measurement10

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Sen

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r R

esp

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se (

V)

28.027.527.026.526.025.525.024.524.023.523.0Distance (cm)

'scan1' scan2 scan3 scan4 scan5 'Mean Fit Line'

σ(intcpt) = 0.0032 V corresponding to σ(x) = 16 μm

=> It’s the holes, not the calibration method !

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Results with new holesResults with new holes

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FR

EQ

-47.60 -47.58 -47.56 -47.54 -47.52 -47.50 -47.48 -47.46Y intercept V

mean = -47.4861 Vrms = 0.0276 V

Histogram of 30 measurements of the Y intercept (Volts of the Sensor Response vs Distance cm)

G-Fitmean = -47.4894 Vsdev = 0.00071 V

mVGauss 75)x(015.0)intcpt(

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

• Random uncertainties: (Dowel hole/pin tolerances, Initial absolute

distance with reference bars) ± 75 μm

• Systematic uncertainties: (including calibration of stepper motor. Mechanical accuracy of reference bars. Non –parallel mover axis and line

connecting R -post and dowel hole ) ≤ ± 150 μm

Current uncertainties in Current uncertainties in absolute R calibrationabsolute R calibration

Total ≤ ± 150 μm

Required: < ± 430 μm (from simulations)

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

Future PlanFuture Plan

• ME+2 : R and Z sensors ready for shipping and installation.

• Start mass calibration for R sensors and Z sensors, Inclinometers for ME+3,+4…

Marion Ripert Florida Academy of Sciences, Tampa, March 18, 2005

ReferencesReferences

• CMS, The Muon Project Technical Design Report. The CMS collaboration, CERN/LHCC 97-32

• Dick Loveless, EMU meeting at Carnegie Mellon, 2003

• http://bulletin.cern.ch/