Applying High Voltage to a Segmented (Clover) HPGe Detector

1. With power off, connect the cables in the following order:
• Preamp cable
• High Voltage cable
• other cables
2. Check that the HV shutdown (inhibit) is plugged from the preamp power supply to the HV supply.
3. Make sure HV supply is set to zero then turn on NIM bin/Preamp power supply.
4. Check LED on the detector, it has three conditions:
• Off:  Detector is cold and ready to accept HV.
• Continuous On:  Detector is too warm

Ø If it was cold, one must wait until detector is warm before cooling again

Ø If it was not yet cold, one must continue to fill detector and wait longer

Ø Blinking:  Detector is at room temperature at it is safe to cool down again

Ø If case 1 is met above:  recorded the peak-to-peak noise on the central contact preamp, preamp currents, etc.

5. Before applying power check that there is noise on all the segment preamps.  If there is no signal from one of the preamps, do not apply high voltage!
6. Check that the HV setting is Positive and the Shutdown signal is Ortec type.
7. While monitoring the preamp signal with the oscilloscope, slowly increase the voltage on the detector. The oscilloscope has to be setup on 200 mV energy scales and ~50us time scales.  The preamp signal will initially “move up” but later recover.  Do not allow the baseline to jump more that 200 mV when you increase the HV. When it recovers it is safe to apply more voltage.
8. Verify the maximum operating voltage for the detector from the individual specification sheets and check if it will hold this bias.