ACIS Threshold Plane Latch-up
The latch-up situation was discussed at some length by the ACIS Science operations group. They have proceeded along 2 parallel courses of action:
- Power-cycle the FEPs before every run that computes fresh bias maps.
- Figure out why the BEP trickles bias maps; develop a S/W patch.
#1 is now fully implemented: the FEPs are recycled before each run in which a bias map is updated. This ensures that a T-plane latchup will only affect a limited number of science runs. Since we have implemented this, we have not observed a single T-plane latchup.
#2 (see ACIS team report).