Prsentation PowerPoint

1
Status of the Alignment 17/12/04 Dario Autiero
2
Measurements taken so far 13/9 TT8 On the
mounting arch 12/11 TT7 Standalone in the
target 19/11 TT7 Standalone with some
improvements 7/12 Tuning for wall 1 (light
conditions) 8/12 Tuning for wall 1
(targets) 9/12 Wall 1 TT7 10/12 TT 8
after wall1 15/12 Wall 1 Standalone 16/12 TT
8 Standalone
3
Coordinates System in measurements with
photogrammetry
The Y axis is along the beam direction (The zero
is on the magnet, Borexino is negative) The X
axis is horizontal going from the rock to the
gallery The Z axis is vertical, going from bottom
to top
All the results are give in an absolute frame of
the magnet, which is measured in Each set of
pictures So we can compare absolute positions in
X,Y,Z among different measurements and
verticality or horizontality

• Units are mm, be careful since the scale of the
  histograms is self normalizing on the range of
  the points
• The position in XZ of the magnetic targets is not
  the same in the two measurements, they had to be
  moved on the end-caps during the cabling, the
  pin targets by construction cannot move
• Each type of Target (magnetic, adhesive, pins)
  has its own offset perpendicularly to the TT
  plane due to the tickness of the Target holder.
  These ticknesses are not subracted from the
  measured values (unless explicitely indicated in
  some plots).
• The long scale calibration with the 4 reference
  point on the magnet is not included (wating for
  the fine direct measurement with a laser tracker)
  it is anyway an effect of the order of 1.5/10000
  which will be negligible for the considerations
  shown in all the next pages. All measurements
  have been checked to be consistent with the 4
  points on the magnet at the mm level.

4
Definition of an absolute  magnet  coordinate
system for the measurements Set 1 and Set2

• We take the points 200-203 measured in both Set1
  and Set2 with the photogrammetry at the same time
  as all the other targets on the TT
• These 4 points are sligthly off the surface of
  the magnet, with an equal offset for the 4
• We define a plane with the 3 points 200,201,203
• We define the origin of the new coordinate system
  in 200
• We take as Z axis (203-200) and as X axis
  (201-200)
• These two axes are orthogonal, a very small
  deviation from 90 degrees is corrected by
  rotating (201-200) staying on the plane
  200,201,203
• The Y axis perpendicular to the magnet is defined
  by the vector product of the Z and X

Z
Y
X
After computing the 3 versors we have an
orthonormal system centered on 200 with the XZ
plane passing for the points 200,201,203
(parallel to the surface of the magnet), and with
the Z axis defined by (203-200) and the X axis
(201-200)
5
Long scale calibration sources installation of
Target holders on the XPC supports, 4 point will
appear systematically in all the measurements.
These 4 points have to be measured once forever
with the laser tracker in order to provide 6 long
distances for the calibration of all the
measurements (replacing the 4 holes made on the
mounting arch) We should also measure with the
laser tracker the 4 holes on the mounting arch in
order to perform a reanalysis of the pictures
taken on plane 8
6
The long distance calibrations are not available
yet, so the results should be considered
preliminary since are based only on the
extrapolation of the local scales, the analysis
will be redone with the long range scales
TT
mm
No significative syst. effects (up/down,
left/rigth) visible on the external control frame
Some latest news from Friday afternoon discussion
with Mario about the position of the bolts on
the magnet that we want to use in order to
provide the long range calibration for the
photogrammetry. See next page
7
The bolts were positioned with the laser-tracker
already with 0.1 mm precision and these positions
are known. In principle they should not have
changed during the assembly of the magnet and
also the M16 hole and the support for the
photogrammetric targets should not have
introduced a significative bias (they should be
both more precise than 0.1 mm). So while waiting
for the occasion to remeasure directly these
positions with the laser-tracker we can already
use this information from Mario. These 6 distance
informations will be introduced in the analysis
in order to calibrate exactely the scales.
Meanwhile, it is quite interesting to compare
Mario's distances with the ones measured with the
photogrammetry by extrapolating the short scale
bars.This use of the short scale gauges is
something that we do temporary in the analysis
just to have a fast result but the final result
in XZ will have to rely on the long distance
calibration. Targets Mario
Photogrammetry with
local gauges 203-202
Horizontal top 8125.0-0.1
8123.7 200-201 Horizontal bottom 8125.0-0.1
8123.8 200-203 Vertical left
5750.0-0.1 5749.9 201-202 Vertical
rigth 5750.0-0.1 5751.5 It is good
to see that the photogrammetry with the last
improvements, even with a scale defined as the
extrapolation of the short scale bars, is already
able to find over long distances the correct
values at the level of about 1 mm.