1. Spectrometer Solenoids MICO 197 Steve Virostek LBNL August 15, 2012

2. Current Status and Plans As of last Friday morning, the magnet temperatures had reached their normal operating condition. The cold mass heater power was running nominally at the same level as during the previous cooldown, indicating that the excess cooling power is now the same (at a constant 1.05 bar pressure). The cold mass helium level dropped to 41% on the upper gauge during the stabilization process. The remainder of the partially full 250 liter LHe dewar was used to increase the level to 78% on the upper gauge. The magnet training will likely resume today, once we have resolved the power supply issue (see next page). We currently have 500 liters of LHe on hand and an additional 1000 liters is scheduled to arrive on Thursday. Each magnet quench requires approximately 500 liters of LHe to cool back down and refill the cold mass.

3. Power Supplies A third Xantrex power supply was installed in the rack so that the power supplies could be connected in the nominal configuration (one for M1, one for M2 and one for E1/Center/E2). A series of current ramps to 20 amps were carried out in order to test the supplies and measure the voltages across the HTS leads. We found that the voltages were approximately the same as compared to that observed in the previous training runs. The HTS lead that replaced the burned out lead had a voltage drop that is two orders of magnitude lower than before. At this point, the worst case HTS lead effective resistance is an order of magnitude lower than that seen on the failed lead (for two of the units) while the other four are much lower than that. There was a performance issue noted with the newly installed power supply that will be explored this morning.

4. 2 nd Magnet The second cold mass/shield assembly is now being installed into the vacuum vessel Next steps will include: installation of the cold mass supports, initial assembly of the cryocooler tower, and installation of the shield ends and application of MLI Mechanical technician help being provided by LBNL at Wang for the assembly of the second magnet has been discontinued until FY13 due to budget constraints – this will likely have some impact on the delivery of the second unit