For the purposes of the shifter, there are two parts of the MicroBooNE TPC that are of importance when monitoring things. This is the Wire Bias Voltages/Currents and the ASIC low voltage/current. While there are many other systems which interface with the TPC (e.g. Drift High Voltage, DAQ readout, etc...) the monitoring and performance of those aspects of the TPC are left for other sub-systems.
There is a basic principle which we attempt to operate the TPC by:¶
Have the system change its state as little as possible and in only graceful ways
What this means is that we have chosen operating parameters and slow control behaviour such that the likelihood the system will suddenly change from energized (meaning having applied wire bias and ASIC low voltage) to off as little as possible. This also means that the ramp speeds and turn-on procedures are chosen such that if the system must change state, it does so slowly and in a controlled way.
1) Wire Bias Voltages and Currents¶
As of 09/22/15 the operating voltages for the TPC wire bias are:
+230 Volts for the collection plane (Y-Plane)
-110 Volts for the induction plane (U-Plane)
These values are now optimally chosen for 70kV with an optimized transparency obtained from DocDB 4708:
This is the bias voltage applied to the collection plane (Y-Plane) and the first induction plane (U-Plane). The second induction plane (V-Plane) has no bias applied to it and is at detector ground
2) ASIC Low voltage and currents
This is the low voltage power which powers the service boards (external boards on the feedthroughs which communicate with the motherboards), and the ASICs on the motherboard. The voltage applied is +/- 3.3 Volts for the various ASICS
The ASICs on the motherboard are shown in schematic form below