IR-2 Configuration Download System
INFORMATION FOR DIRC OPERATIONS
This note gives some information concerning the solenoid and bucking
coils, and describes the monitoring of the fringe field using the
DIRC magnetic probes.
I. Solenoid and bucking coils: demagnetization of DIRC shield
The nominal operating currents of these coils are 4600A and 200A,
respectively. They can be ramped together minimizing the
magnetization of the DIRC shield. However, the power supplies
cannot ramp down together all the way to zero, thereby magnetizing
the shield each ramp down.
Normal operating procedures is to ramp up the solenoid and bucking
coils together, and then to demagnetize the DIRC shield via a
cycle (available on cryo display) which ramps down the bucking coil
to 0A in 2 minutes and then up to 260A in 2 minutes, and then down to
200A in 2 minutes. This cycle ends with the bucking coil at the operating
current AND with the shield demagnetized.
There is also a demagnetization cycle with the solenoid off. This cycle
requires the frequent reversal of the bucking coil power supply and
takes about 30 minutes.