[Dsg-rich] RICH assembly

[Marco Mirazita]

Hi all,
here we try to answer to the questions raised in the last couple of days 
on the RICH assembly.

1) Winch load
The weight of the RICH fully assembled is about 1000 kg, including the 
stiffening elements. This would be the number to be consider if we had 
to lift the RICH from the floor with the winch.
Instead, we want to use the winch to rotate the RICH on top of the 
assembly structure. Thus, the maximum pull force that the winch must 
apply has to be calculated in this conditions. This has been done time 
ago, as you can see in the two attached slides. The resulting maximum 
pull force is about 7750 N, with a 25% safety margin we reach 9700 N, 
that is a weight of 990 kg, lower than 1000 kg.
The procedure for the load test should be defined based on the foreseen 
usage of the winch.

2) Eye bolt
We agree to use the hoist ring as suggested by George. The depth of the 
threaded hole in the aluminum angular element of the RICH is 50 mm. The 
bolt is screwed to the RICH passing through the bar of the stiffening 
element, which is 10 mm thick, 15 mm if we consider also the washers. We 
need to screw the M24 bolt at least for a depth of 35 mm in order to 
have a grade 8 connection. Thus the bolt should be at least 35+15=50 mm.
If JLab can provide them, it would be great.

3) Assembly structure
We thank DSG to have volunteered to continue the assembly of the 
structures. We agree that the early completion of the assembly will save 
time for the many other tasks we have to do, so please go on. We suggest 
you to perform a preliminary planarity check of the base plates before 
mounting the vertical posts. A final alignment check of the structure 
can be done when Dario and Sandro will be at JLab on march 6, and then 
you can proceed together with the assembly of the rotation elements. 
Please don't hesitate to contact us in case of doubts or troubles.

4) Documentation
We are preparing the documentation for the assembly procedure of the 
electronic panel support. We will also include the description of the 
mechanical assembly of the boards on the panel.
The assembly of the mirrors will not be done before few months. In 
addition, we planned in the next weeks a test of the assembly of the 
aerogel on the planar mirrors. The results of these tests may impact the 
procedure of the mirror assembly, thus we will work on the procedure 
documentation after these tests.
For the electronics tests, it is up to the electronic group.

Dario, Marco, Sandro, Vincenzo
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