Power Supplies and Electronics Procedures

The power supplies and readout electronics associated with the HRS VDCs are all commercially designed. The reader is directed towards the manuals made available by the manufacturer for the detailed information not provided here.

The Bertan 377N HV power supply provides -4.00 kV nominal to each of three HV planes in a given VDC detector package via a 10M Hammond splitter box (see Figure ). The power supply is located in the detector hut in a NIM bin on the upper level of the space frame. This unit may be controlled either manually or remotely via the EPICS control software, and also provides a monitor of the current drawn (nominally 70 nA) by the VDCs to which it is attached. Connections from the power supply to the Hammond splitter box, as well as from the Hammond splitter box to the VDCs are made using standard SHV connectors mounted on red RG-59/U HV cable good to 5 kV.

The Kepco ATE 15-3m discriminator power supply provides +2.5 V (46 cards draw 2 A) and the Kepco ATE 6-100m pre-amp power supply provides 5 V nominal to the 26 LeCroy 2735DC pre-amp/discriminator cards used to instrument each chamber via a heavy-duty fuse panel. The precise voltages provided are +5.0 V (46 cards draw 22 A) and -5.2 V (46 cards draw 58 A). These LV supplies are located in the detector hut on the main level of the space frame. Complete connection schematics and instructions for making or breaking the connections are located on the aluminum Faraday cage protective plates covering the respective interface nodes between the power supplies and the VDCs.

Each VDC wire plane consists of 400 20m , Au-plated tungsten wires. The first 16 wires on each end of the wire plane are connected to ground for field-shaping purposes. There are 368 wires per wire plane which act as signal wires. Thus, each spectrometer is instrumented with 1472 channels of LeCroy 1877 multihit FASTBUS TDCs. These TDCs are located in a Bira 8000 FASTBUS crate located on the main level of the spectrometer space frame in the detector hut. The connections between the pre-amp/discriminator cards mounted on the VDCs and the TDCs are made with 16-conductor twisted-pair cables. Clip-on ferrites are used to filter noise. A connection schematic is posted on the side of the rack holding the FASTBUS crate on the space frame in the detector hut.