sPHENIX discussion of the superconducting solenoid

["Yip, Kin" <kinyip AT bnl.gov>]

Hi,

Today, early in the morning, Nicola (CERN) noticed that the mapper stopped after 6:24 am.  He drove to 1008 from hotel.  Though he initially got it going for 11 minutes or so, it stopped again.   Nicola at that point went to hotel to bring his technician colleagues to 1008.   They concluded that we had to open the pole-tip doors and so I ramped down the magnet.  The doors could be opened after 10 am or so.

When the doors were opened, it's found that the edges of the mapper arms were hitting some tubes and surfaces of the EMCAL.   EMCAL experts helped remove the tubes.  The Survey Team later (11:20 am) came and determined that the rails didn't actually move.   Apparently, the surface of the bottom EMCAL module(s) near the northern end seems to be slightly higher.   CERN team technicians (Raphael and Francois) did quite a bit shimming while Nicola controlled the motion of the mapper.

The CERN team finished the work around 1:30 pm or so but the sPHENIX technicians didn't come back from their late lunch after 2:30 pm or so.  after the doors were closed, I could start ramping at about 3:26 pm and reached the full field at 5:10 pm.   We started mapping at 5:12 pm and it ended around 10:58 pm (just now !).   Finally, we completed the 44-hour run (more fine/detailed mapping). 😁

Now, I'm ramping down the magnet to 0 A and then ramping it to half field.   I didn't go to half field from the full field but go to 0 first because people were worried about the hysteresis, as the B-H state from 0 to 2310.15 A may not be the same as the B-H state when we go from 4620.3 A to 2310.15 A.

It'll be after 1 am before I will finish this ramping-down and ramping-up processes.    John Haggerty will take over after that.     I'll come back at 8 am to "release" him.

Kin