Following are the minutes taken at the May 28 teleconference session of the
grounding and shielding working group.  It seems that there are open issues
to keep tabs on:
1.  Trigger supervisor interconnects
	Possibility of ground loops from the connections between the high
voltage inhibit module and the power supply systems in the collision hall -
plug pmt's and svx at the minimum.
2.  Calibration hardware
	Ground loop made by the Xenon flasher high voltage cable.
	Changes in the  Cal Card interconnects due to RABBIT --> VME
	The wall system is a big unknown at present.
	The plug source system is a big unknown at present.

********************************************************************************
From:	SMTP%"nelson@fnal.gov" 29-MAY-1998 08:00:46.32
To:	ELIAS
CC:	
Subj:	Summary of Mike Schmidt's TSI interconnections presentation.

John,

   Below is a summary of Mike Schmidt's presentation on Trigger
Supervisor interconnections.
                                                       -Charlie

==========================================================================

   Mike Schmidt gave a thorough presentation on the TSI interconnections.
Many of these run between crates in the trigger room, and are not of
major concern to the Grounding/Shielding Committee. 

   Of the two interconnections to the collision hall, both go to the
TRACER modules in the front-end crates. One is optical fiber. The other
is copper. It transmits BUSY/DONE/ERROR signals from the TRACERs to the
TSI. The three signals are LVDS levels.

  This link will have a shield, which will be hard-connected to ground
at the TRACER. The upstairs end goes to an interface card in a TSI crate.
There the shield connects to local ground via an (optional) capacitor.
The LVDS termination resistors are split into two, and each middle node
can be connected to the shield with its own series R and C termination.
This is the recommended scheme for shielded copper links between systems
separated by some distance, and especially for links between the collision
hall and upstairs.

   Mike expressed some concern over a coaxial connection to the front
panel of the interface card in the Trigger Supervisor crate. This is the
HV inhibit signal. The connector would be Lemo. Since some of the HV
inhibit signals might be originating downstairs (plug calorimeter, SVX ?),
the link would cause a ground loop unless the coax shield is isolated at
one end. Mike said he could do that at the interface card.

==========================================================================

From:	SMTP%"hahn@fnal.gov" 28-MAY-1998 18:09:47.68
To:	ELIAS
CC:	
Subj:	Re: Thursday Teleconference

Hi, John,

   Here's my summary of the calibration system review:


   * Central:
        o Brief measurements on several wedges showed no ground connections
          (that is, to the wedge steel) from any of  the I/O auxiliary card
          inputs (which are connected to the source motor and limit switches),
          the xenon flasher box inputs, or the LED box inputs.  Good news!
        o The xenon flasher box HV input needs to have its shield connection
          broken at the xenon box via a resistor (if this is not already the
          case).
        o During timing tests, Michele and I observed large radiated fields from
          the HV cable (>10 V with a scope loop) as the xenon bulb was
          discharged.  This may dictate cable routing.  Also, will this feedback
          into signals taken during xenon runs?
        o We should understand how the Run 1 connections for the RABBIT CAL card
          are altered (presumably all through the J3 connector) for the Run 2
          VME CAL card.
   * Endwall:
        o A group responsible for the endwall in Run 2 still needs to be
          identified.  Aesook is working on this.
        o I will try soon to open up an endwall cover and check the connections
          to the CAMAC system upstairs for any connections to detector steel.
   * Plug:
        o We should nominate a system expert - Virgil Barnes?  Alvin Laasanen? -
          to give us run-down of plug source system?  Do we need to worry about
          any other calibration system (e.g., laser)?

Steve

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