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User name gomez
Log entry time 14:38:35 on October15,2000
Entry number 50472
keyword=Left Q2 current oscillations
Current oscillations of order several tenths of a percent were observed since about
8 AM today. Login into the Left spectrometer magnet control IOC (hallasc14)
did not show any errors (dead processes or communication problems).
Visual check of the Q2 power supply and DVM downstairs did not show
anything abnormal either. A reboot of hallasc14 was attempted which gave one error:
the Left dipole current DVM had lost its assigned GPIB address.
This is a sign of radiation scrambling the internal memory of the DVM
(these DVMs are located next to the power supplies and not shielded).
Since no problems were otherwise found, we are left to speculate that Q2 DVM
may have also being affected by radiation (like the filter mode).
Recall that in the case of the Quadrupoles Q2 and Q3, the DVM readings are used
in an active feedback loop to control the power supplies output.
Consequently, wrong readings of the DVMs will affect the power supply output.
One could use the Hall probe readings for cross check.