After digging my way in to the interior of the glacier I noticed that I was beginning to sound like My favorite duck so I climbed back down to see if there was another fool in here on a nice sunny saterday that I could rope into pulling my body out if the cave if I passed out.
Enter Jack But with his bad knee he couldn't climb the drift so we hooked a chain to his golf cart and to my harness and off I went with a torch in one hand and and my trusty ice ax in the other.
After clearing away most of the snow I located the source of the problem. One of the lead isolators has sprung a leak (the left one) and was spewing out He and liquid air faster that I could heat it up and chip it away with my ax. I climbed back down the drift to swich the 04 and 16 valves to local and close them, expecting this to stop the plume.
But no, this didn't stop it. at a loss I called the guard in order to get permition from the cryo on call to switch from cold to warm return. In no time I got a call from Buddy Carlton with clown music in the background ( the only thing more fitting would have been a yodeler's covention). He said to go ahead so I did and noticed that there seemed to be a LOT more flow than normal going through the warm return line but I thought it might have been the thin air and didn't consider it(first clue).
As the sound of high presure gase receded from the warm return line so did the leak in the lead isolator( second clue) along with the pretty blue ice (third clue). I climbed down the ladder and asked Jack to look at the !@#$%^& liquid level meter to see why the level had over filled the magnet through the leads (way off base), and went to see how much ground we had lost on the cooldown to prepare myself for the !@$$ chewing I was going to get on monday from the person (Heidi) doing the cooldown.
I found that all flow to the hall had stopped. All of the magnets were warming up and that ESR was "just fine honny". Needless to say I was perplexed and called to talk to Buddy again. He decided that he would come in before I distroyed anything and was here in no time. After taking time to study the situation Buddy determined that there was nothing wrong with ESR and all of the valves between ESR and Hall A were open. He was also conserned that the magnets and transfer lines were warming up and thought that we should do something in case the blockage should open. We decided to switch all of the magnets to warm return in order to protect ESR. We noticed that when we switched the Quads to warm return the flow to the Hall returned and the supply transfer line cooled. (fourth clue)
Because of this, we determined that it was the cold return transfer line that was blocked (fifth clue, did you get it yet). we set up the left Q2, Q3, and dipole to 5% open on the 16 valve to try to keep in somewhat cold over the weekend and deal with it on monday hoping that the blockage would be taken care of by good gnomes.
I believe that the blockage preceded the isolator blowout, and that the
Q2, Q3, and the dipole were using the return path through the
spectrometer transfer line to the dipole to the dipole leads(the only
leads open in the hall. the first stage relief on the dipole was also
cold and this may have been another path. this would also explain why it
was so hard to get liquid in the magnets. This blockage may have been the
for some time.
A copy of this log entry has been emailed to: fansler@jlab.org, folts@jlab.org