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
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
10
8
6
4
2
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
14
12
10
8
6
4
2
0
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(
10
8
6
4
2
0
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
9
8
7
6
5
4
3
2
1
0
Sen
so
r R
esp
on
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
10
8
6
4
2
0
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