Drawing used for the study:
E0’ drawings:
Height of the
refer
250mm
352mm
ence point with respect to the support frame:
The height of the module above the support point A at the bottom of the support leg
(drawing TD-1024-024) is:
Height = 250 + 40 + 38.1 = 328
Height of the nose of the supercrystal (point B) with respect to the base of the triangular
support:
Height (AB) = 204 – 274sin (10.47) +328cos (10.47) +392sin (10.47) = 343.9
Height (CB) = 343.9 + 204 = 548
According to the survey of 24.06.2003, the table in its horizontal position is at 672 mm
below the beam height. Therefore, the E0’ assembly was placed at a height of (672-548)
=124 mm of the table.
How to move the table to a requested position
When looking from the beam to the module we consider axis x horizontal pointing to the
left and axis y vertical pointing upwards.
The angle created by the horizontal movement of the table is angle β
The angle created by the vertical movement of the table is angle φ
These two angles are measured from the zero-point (βzero ; φ zero) on the module to the
requested point. βzero is expected to have a value near 63.43 °; φ zero is expected to have a
value near 0.
We start from the situation where the beam points to the centre of the four supercrystals
on the table.
In the following we assume that the distance of 3198 mm towards the imaginary
interaction point does not change. This is correct at the 0.5% level.
-For a move on axis x to the new coordinate x1, at first approximation the move will be:
β = sin-1 (x1/3198). This initial value of β is only used in the estimate of the movement in
the vertical direction.
-For a vertical move to the new coordinate y1:
Correction of φ = -sin-1 (y1/sqrt((1430 + x1*cos(90 - β zero - β))2+y12)
While doing this we change the lever arm for the φ movement as viewed in the direction
of the beam and we use this to correct the horizontal position accordingly:
Correction on x: sqrt((1430* cos(90 - β zero - β) + x1)2+y12) – 1430* cos(90 - β zero - β)
towards Saleve, which yields:
Correction on β = -sin-1 ((((1430+ x1/* cos(90 - β zero))2+y12)* cos(90 - β zero ) – 1430*
cos(90 - β zero ))/ 3198)
Survey of the E0’ module
On Monday 24/5 the E0’ module was moved to the beam position and a survey was
carried out.
We collected the following information throughout the day:
At η=1.479, the movement between crystals of EB corresponds to 2115 encoder counts in
vertical direction (0.0175 rad=1 degree) and 3100 counts in horizontal direction
(Δη=0.0175=0.44 degrees at η=1.479). This seems to correspond to 7045 counts/degree.
At its charging position (horizontal level), the vertical encoder indicates 32306 counts.
With the help of the geometers, the 4 external corners of the module were placed
consecutively in the beam:
The corners are denominated as such (seen by the beam):
D
C
B
A
Table coordinates for corner positions:
Corner
β
φ
Offset horiz. (mm)
A
457056
32236
0.3 too much Saleve
B
438370
32465
0.6 too much Jura
C
455663
19821
0.2 too much Jura
D
437022
21066
0.1 too much Saleve
Offset vert. (mm)
0.7 too high
0.4 too low
0.5 too high
0.1 too high
When corner A was in the beam, the vertical angle of the back plate was measured: 10.39
°.
The horizontal angle between the backplate and the beam line was also measured: 12.95