It is anticipated that for some Pisa runs, for example those for
embedding studies, it will be necessary to be able to shift the VTX a (small)
distance away from its ideal position at (0,0,0). I added variables to
phnx.par:
sili_br_par
...
vtx_shiftx = 2.22,
vtx_shifty = 1.11,
vtx_shiftz = 0.0,
$end
so that the whole vtx can be shifted in x,y,z. In the example, by 2.22 cm
in x and 1.11 cm in y.
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| Top view, where the shifts are (10.0, 0.0, 10.0) cm. | 
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| Beyond this, the VTX does not currently allow for fine adjustment of individual ladder placement. The problem with the implementation of this feature is that the elements that make up a single ladders are not grouped into a single mother volume, making this very hard to do. What needs to be done is to build up a ladder with all its bits and pieces inside a single mother volume, here shown in blue. | 
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| Next, the boxes are assembled into a layer, as shown here. You see that the ladder boxes ovelap. This is allowed, but they need to be declared 'MANY' instead of 'ONLY". These volumes then must enclosed in a holder volume. | 
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| Here is the holder volume for barrel 3. The same is done for barrels
1,2 and 4. The barrels are placed in the green West half barrel, which are
finally placed in the yellow enclosure.
This hierarchy allows for the efficient fine adjustment of ladders, barrels and half-detector placement. | 
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Hubert Van Hecke Last modified: Sat Feb 8 11:53:13 MST 2014