Optical alignment for BOL 05, BOS 04, BOS 06 and BOS 16 Egge van der Poel, Nikhef on behalf of the M

1
Optical alignment for BOL 05, BOS 04, BOS 06 and
BOS 16 Egge van der Poel, Nikhefon behalf of
the Muon Barrel Alignment group
Fitting chamber positions with praxial
sensors ASAP absolute mode fit
2
We have very few geometer tags for the
barrel Therefore a mode of study different from
endcap methods is needed The presented work
(i.e. using praxial sensors) is part of this
study Extension is expected by adding other
sensors (e.g. axial, projective)
3
Reminder praxial sensors
x
RASNIK coordinates
y
z
Atos An Aramys tool to show Setups
Modified for Asap
4
Procedure for debugging praxial sensors
1) Put large measurement errors perform first
fit 2) Plot histograms of the residuals after
first fit (measurement simulation) estimate
RMS values 3) Put these RMS values into second
fit as measurement errors 4) Compare chamber
positions from this second fit to manually
measured chamber positions in the pit 5)
Investigate discrepancies
5
Step 2 Residuals after the first fit (BOS 06)
residuals for praxial x measurement
x
y
z
residuals for praxial y measurement
gt dispersion of 260 microns along y (along
tubes) has to be understood
6
Step 2 Residuals after the first fit (BOS 06)
residuals for praxial mag measurement
x
y
z
residuals for praxial rotz measurement
7
Step 2 RMS of the residuals after first fit
BOS 06 BOLC05 BOSA16 BOSC16 BOS 04 sigma(x)
mm 0.083 0.075 0.048 0.039 0.052 sigma(y)
mm 0.258 0.172 0.120 0.170 0.095
sigma(rotz) rad 0.00044 0.00074 0.00046 0.00054
0.00062 sigma(mag) 0.0011 0.0042 0.0048 0.002
5 0.0018
sigma(mag) 0.0011 0.0042 0.0048 0.0025 0.0018 sig
ma(z) mm 0.138 0.526 0.602 0.313 0.226
8
Step 3 result of second fit
9
Step 4 compare interchamber distances from
second fit with pit reality
Z
X
x
Y
BOS5A06 and BOS3C06 are known to have a tilt
around the tubes on RO side to be fixed soon
10
Step 4 compare interchamber distances from
second fit with pit reality
observed discrepancy between fit and pit reality
Sector 06
Sector 16
Sector 04
unknown problem with BOS2C16_BOS3C16_HV
missing sensors CCD not connected
11
Step 4 compare interchamber distances from
second fit with pit reality
discrepancy (cut lt 1mm) between fit and pit
reality
12
From here on
To reduce the RMS for the discrepancy between
absolute alignment fit and pit reality i)
recent optical data is needed current problems
with DAQ need to be solved ii) (recent) MDT
interchamber-distance measurements are needed (-gt
contributions are very welcome!) new (accurate)
measuring device ordered needed to measure below
current 1 mm accuracy iii) observed
discrepancies need to be investigated further