User name S. Sirca
Log entry time 11:16:31 on November 5,2007
Entry number 212653
keyword=Report on cryotarget recovery
JP managed to recover the LHe target.
Reconstruction of events leading to the target vent:
Channel 1 of the Loop 1 cryo controller (corresponding to the
bottom-most temperature sensor in the LHe loop) freaked out.
The temperature value passed on to the PID failed to update
i.e. it got stuck at 7K, and the heater power was driven up.
Ultimately the pressure exceeded about 220 psia (this is
the last value we saw on the screens) and the target vented.
(Vent valve limit presently set to about 200 psia.)
Obviously, the Loop 1 cryo-controller was power-cycled prior to the recovery.