1. Spectrometer Solenoid Update Steve Virostek Lawrence Berkeley National Lab MICE Video Conference 120 May 7, 2009

2. 2 Second magnet assembly including all fixes and modifications has been completed Second magnet had been cooled to 5K (cold mass) and transfer of LHe was under way An internal leak developed between the cryostat and the insulating vacuum (1 week ago) Magnet has been warmed up and leak checking is under way Leak is likely in either the cryostat fill or vent lines LN cooldown system developed at FNAL has been installed Temperature logging system developed at LBNL is working First magnet is completely disassembled and fixes are well under way in preparation for reassembly Additional cryostat penetrations and extra vent line added Modifications to vent line are nearly complete Summary

3. 3 LN Cooldown of Magnet Cooler He lines Transfer line

4. 4 LHe Transfer into Cold Mass Fill line turret Transfer line Vent line turret

5. 5 Steps Leading up to Leak Magnet had been cooled to 5K (cold mass) and transfer of LHe was under way LHe dewar was changed, and no flow through the system could be attained Vendor suspected an ice blockage and attempted to thaw out fill line with heated helium gas Blockage remained, so vendor attempted to transfer LHe through the vent line containing an unprotected bellows An internal leak developed between the cryostat and the insulating vacuum causing the cold mass temperature to rise and the external vacuum vessel surfaces to frost Leak is likely in either the cryostat fill or vent lines A leak near or in the vent line bellows is the easiest repair

6. 6 Possible Leak Locations Conflat seal Al/SS transition Weld joints Bellows

7. 7 FNAL LN Cooldown Control System Heaters Thermocouple Control system chassis Flow control valve LN System was successfully operated during cooldown Modifications to control circuitry under way to optimize performance

8. 8 Temperature Logging System in Use System now operating 16 channels being logged User can specify logging time increment

9. 9 Temperature Logging System Screen Shot

10. 10 First Magnet Cold Mass Modification

11. 11 Power Supply Racks Two power supply racks have arrived from RAL Installation of power supplies and discharge circuits are under way Spec supplied by RAL dictates locations of components

12. 12 Locate exact location of vacuum leak (today or tomorrow) Develop plan to make necessary repairs (depends on the accessibility of the leak location) Make the repair while maintaining the integrity of the magnet insulation (subject to review by LBNL) Initiate cool down of the magnet (~1.5 week process) Run the system at operating temperature for ~24 hours to ensure recondensing system is functional Power the magnet and train coils Warm up for shipping to FNAL Upcoming Tasks