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Sarah Lockwitz, 12/06/2015 11:09 AM

Cathode High Voltage - Troubleshooting

What to do if....

The voltage on the pick-off point changes

If the value changes to a new value like this:

Don't worry. This happens regularly:

HV Minor Alarms
Post in the e log. The HV is set to minor alarm if the 5 second pick-off point average differs by more than 0.1 V from the 60 second pick-off point average.

HV Major Alarms

The HV is set to major alarm in the case of a PS going to 0 V when it should be at a drift voltage, and also in the case of the pick-off point being more than 0.2 V from -216.86 V. Call the HV expert. They will monitor the situation.

The HV supply trips

First, call the run coordinator.
If it is not between the hours of 10 pm - 7 am, call the HV expert. Otherwise, call them in the morning. The detector will need a full system checkout -- we will not be ramping the voltage in the middle of the night.

Crash button

If the HV must be ramped down, it is best for an expert to use the expert GUI.

In the rare case where all else has failed and the HV must go down, the power button on the Glassman supply can function as a crash button. This is not the default method to ramp down. It will create a sudden drop in voltage in the entire system stressing components. The power button is highlighted below.