[Halld-tracking-hw] CDC Ground Connections

[Curtis A. Meyer]

Hi Everyone -

     a couple of points on the grounding connection.

    Sometime ago, we had proposed "continuing" one of the legs that 
supports
the connectors for the HV-boards through the gas plenum to the endplate. 
This
standoff would then serve to both support the HV connector and provide a 
solid
ground connection to the end plate. The one concern is that it might not 
be possible
to place one support for each connector such that the feed through can 
carry through
to the end plate.

    Assuming that the above is not possible (which we still feel would 
be the best grounding
and support scheme), then we are worried that there are not enough stand 
offs in the current endplate, there are only eight as far as we can tell 
in the current design.

    We are very concerned that there are not enough standoffs to support 
the swiss cheese
plate, particularly during insertion and removal of the high-voltage 
cards. What we see with
the models that we have at CMU is that the force needed to insert and 
pull the card is
sufficient to actually compress or pull-out the plastic plates. The way 
the connection
scheme now goes. This distortion becomes a force either directly on the 
crimp pin,
or on the glue joint that seals the chamber. These have the potential to 
break wires
in the straws or break the gas seals every time a HV board is changed.  
It is important
that additional standoffs be added, either during or after manufacture 
of the Al endplate.

    Finally, assuming that we adopt Fernando's connector, we need to 
know if there is a
source of the .020 male part that can be soldered to the .040 wire and 
is inserted in the
press-fit hole. The connector itself is quite slick and the 60gm force 
needed to engage
it seems fine. But the male part is equally important to this working.


     -- Curtis

  

-- 
Prof. Curtis A. Meyer		Department of Physics
Phone:	(412) 268-2745		Carnegie Mellon University
Fax:	(412) 681-0648		Pittsburgh PA 15213-3890 
cmeyer at ernest.phys.cmu.edu	http://www.curtismeyer.com/