Far Detector Grounding

  • Proposal for Far systems
  • Details of MUX Box electrical isolation

Near Detector grounding

No documentation, but the Alner phototube boxes do not need to be isolated in the manner which the Far MUX boxes do

DAQ Grounding

Slides on DAQ grounding from the DAQ Review, July 2000; 5 pages, PDF format

DAQ Grounding Summary - July 2000

The FEE is not foreseen to be adversely effected by the DAQ system, in particular by the DAQ components in the readout crate. The PVIC inter-crate connection system has been specifically designed for applications like the one used in the MINOS readout and by careful attention to other subsystems in the readout crate any risk of creating ground loops or noise injections can be minimised.

  • DAQ system components which may effect the FEE
    The only DAQ system components which are close to the Front End Electronics are the ROP (6U VME Readout Processor) and the PVIC (6U carrier and 2 mezzanine cards plugged on this card). These two cards are "joined together" by a side connector which joins the two cards together (through PCI bus) and for our purposes can be viewed as one unit.
    The ROP and PVIC together have the following external connections:
    • LV power (+5v) and ground connections to the crate power supply.
    • Ethernet port (10 base-T).
    • Two RS232 connections - one to a closeby converter (RS232 to Ethernet) and another to the Timing Receiver Card which is situated inside the readout crate.
    • Electrical PVIC (shielded differential PECL multi-core cable which is being connected to three other neighbouring crates).
    • Optical PVIC connection to the Farm.
  • Differentiation between Shield and logical grounds
    The front panel of the ROP (RIO2 VME processor and PVIC) modules is separated from the Low Voltage ground by a 'jumper and two resistors in series' connection. In other words the front panel ground can be entirely isolated from the LV (logical ground) by removing this jumper. However the front panels of all the VME cards in the readout crate will be connected to the crate chassis which is connected to the ac ground (earthed) as a safety measure. Provided the earthing is done well in the power distribution to all the crates there should be no adverse effects to the LV grounds when these four crates are connected together through the cable shields.
  • Other system considerations
    The front panels of the other cards in the readout crate namely the VARC and TRC should also be isolated from the LV grounds so that there are no adverse effects.
  • Full Optical interconnection
    It should be noted that a possible (but not yet proven) second option being considered is to replace all electrical PVIC connections with optical ones. Until this is proven it remains only a possibility but we are actively investigating such an option.