Determining Charge Breakdown

Charge breakdown measurements are important because they help us decide what the highest bias can be applied to the signal before the charge signal breaks down from the electric ﬁeld. There will be multiple tests between charge inner and charge outer tests on the same side of a detector and across the detector as well. A bias sweep will be performed to determine at what point charge breakdown begins to occur.

Make sure all of the boards are set up and powered properly.
The detector should have been ﬂashed for at least an hour and settled at base temperature.
The number of tests you must perform depends on the number of charge channels and dibs the detector has. Click here to look at an example of charge breakdown results. This detector had an inner and outer charge channel on both sides of the detector (thus, 2 dibs). The same type of tests must be performed on the detector you are testing.
To conduct the charge measurement tests, you will use both the detector control and readout vi. Make sure you are viewing all channels at the same time.
On the FrontEnd settings tab on the control vi you will apply 1 V (for one of the electrodes) to the appropriate charge channel and observe to see if there is any ﬂuctuation in any of the channels’ signal baseline. To apply the correct bias on the control vi, go to the charge bias calibration section here. Each DCRC board has been calibrated with a DMM in order to get the proper bias delivered to the charge electrodes. Make sure to scroll down to the table that has DCRC30, 33, and 32 listed together. Those are the current values we wish to use.
After applying the initial bias, if there is no charge breakdown, increase the bias by 1 V. Again, reference the table for what 2 V requires. You will continue to apply bias and check for charge breakdown. If you detect a small hint of charge breakdown, then lower the bias steps to 0.5 V. Make sure you take notes on what you see.
Once you complete a bias sweep for one charge bias conﬁguration, set all of the charge channels back to 0 V and ﬂash the detector for a few seconds.
When the base temperature has stabilized from the ﬂashing, select a new charge bias conﬁguration to continue with the charge breakdown tests.
Summarize the results you found on the run summary page, as done in the example referenced.