The BLS (Base Line Subtractor) system electrically sits between the Preamps and the ADCs in the Calorimetry electronics. The system has a total of twelve 3-rack units that are located below the cryostat. There are four units in each section, CC, ECN and ECS.
Each BLS system is wired in the following manor. Cabling view from the back of a three rack system.
Each 3-rack unit contains six BLS crates, three in the left rack and three in the right rack for a total of 72 BLS Crates.
The center rack contains the BLS power supplies, AC distribution and the Calibration Pulser. The three rack system is protected by a conventional smoke detector, VESDA , water flow and leak/drip detection. A fault from one of these detectors will disable the power supplies.
Each BLS Crate contains the following Cards
|1-Crate Bus Controller Card 3740.412-ED-255715 Page 1
2-Analog Driver Cards 3740.412-ED-255716
1-Crate Monitor Card 3740.412-ED-255874
16-BLS Cards Stony Brook HEP
1-Crate Bus Terminator Card 3740.412-EC-255711
The BLS Cards are new and documented separately. The BLS card (Mother Board) document provides details of the card with tests conducted to verify the safety aspects of the card. All other cards are unchanged from Run I and referenced for completeness.
The BLS Crate will have a new P2 backplane along with a change in the DC power harness as described in this documentation. The P2 back plane construction was designed to handle the fused currents available from the power supply. Information about the design is documented in the BLS Back Plane.