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Ancillary Requirements
The following is the specification of the HV generator that we are considering as the HV source for RICH PMTs.
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This means that we need to have DAC card with > 6 Volts output and better than 10 bits resolution to control the High Voltage. Also we need ADC card that accept > 1.8 Volts with 10 bits or better resolution to monitor the output voltage.
The current plan for RICH High voltage controll system is the following:
We will use the COM20051 chip from SMC as ARCNET controller + micro-controller for the High voltage control board.
One controller controls 16 to 32 HV generators. The control setpoints and readback is through DACs and ADCs respectively. The high voltage generator has a voltage contol input and a monitor output (1/1000 of output high voltage). The controller reads the monitor voltage, and adjusts the DAC output so that the HV output is at the "set-point". We have 640 HV generators to control, each of which supply 8 PMTs. Therefore we have 20 to 40 controller (ARCNET node) for the RICH HV control.
The HV control commands (set points, tolerance, turn-on/off, etc. The format of the commands and its functionality is to be defined) are sent through ARCNET from a "host" computer. We will program the com20051 processor so that it interprets the command, and control the HV generators through ADC/DAC connected to the chip.
Yasuyuki Akiba email: akiba@ieux01.ins.u-tokyo.ac.jp