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Spectrometer Solenoid Update

Spectrometer Solenoid Update. MICE VC 149 May 31, 2012. Steve Virostek - LBNL. 1st Magnet Progress. After the extended pump and warm N 2 purge, the insulating vacuum reached 5.8x10 -6 Torr ( RGA water peak = 3.5x10 -6 Torr, rate of rise = 1.08x10 -8 Torr/sec)

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Spectrometer Solenoid Update

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  1. Spectrometer Solenoid Update MICE VC 149 May 31, 2012 Steve Virostek - LBNL

  2. 1st Magnet Progress • After the extended pump and warm N2 purge, the insulating vacuum reached 5.8x10-6 Torr ( RGA water peak = 3.5x10-6 Torr, rate of rise = 1.08x10-8 Torr/sec) • LN2 pre-cooling began on May 22nd and lasted ~3 days, using 12 each 240 liter dewars and reaching ~100K • After 5 cold mass pump/purges, LHe cooling began on May 25th; 1500 liters of LHe were used in <1 day to cool down to <5K and fill the cold mass 2/3 full • Initial problems with the LHe level gauges and the Cernox temperature sensors at <5K have been resolved

  3. 1st Magnet Progress • With no current in coils and at steady state, the cold mass pressure dropped to <0.4 bar absolute, indicating a closed system with excess cooling capacity • The cold mass heater is currently being used in a feedback loop to maintain 1.2 bar absolute pressure • The exact level of heater power is not known at this point, but we are working on this • The radiation shield is significantly lower in temperature than in previous testing: 40 to 42K compared to previous 90 to 100K

  4. Cooler operating LN2 Cooling LHe Cooling Cold Mass sensors Second stage head First stage Cooler LN2 Dewer Change

  5. 1st Magnet Progress • Training runs will proceed after delivery of additional LHe; short supply of helium is now delaying the process • Our supplier and LBNL contract rep has indicated LHe should be available tomorrow or early next week • We are also exploring borrowing LHe from other local labs (LLNL, SLAC); short LHe supply could be an ongoing problem for the Spectrometer Solenoid testing as well as MICE operation at RAL • Actual quantity of LHe needed will depend on the number of training runs required

  6. 1st Magnet Progress • Off line power supply tests were completed yesterday • The actual magnet coils will be ramped up to ~10 amps and back down today as a further test of the power supplies and control system • Based on the preliminary results of the cooldown, the changes to the magnet design appear to have had the desired effect on performance

  7. 2nd Magnet Progress • All sensors and heaters have been installed on the cold mass, which has been wrapped with MLI • The radiation shield has been assembled around the cold mass • The vacuum chamber is having some grinding work done to prepare for the welding of the support feet • All 8 cold mass supports have been wrapped with MLI and are ready for installation • The additional 6 two-stage coolers at Wang have had their new hardware installed; the sensors will be installed after calibration at Fermilab

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