1. Spectrometer Solenoid Update Michael S. Zisman Center for Beam Physics Accelerator & Fusion Research Division Lawrence Berkeley National Laboratory MICO Meeting—RAL July 6, 2009

2. MICO:Zisman2 Status (1) MZ and SV have been at vendor for the last several weeks —Bross and Freemire joined us and set up Fermilab cool-down system Cool-down system worked well —eliminates serious risk of getting substantial air or moisture into fill line —provides automated process for LN cooling that maintains acceptable pressure and acceptable temperature difference between cold mass and cover o ABr, BF, MZ, and SV provided 24/7 coverage during cool-down Ran out of LN during cool-down (at ~130K) and cooled the last portion with LHe —would otherwise have switched to LHe at about 90K

3. July 6, 2009MICO:Zisman3 Status (2) After cooling down, we had to wait for replacement cryogens —started magnet training on Thursday, July 2 o operating with all five coils in series (goal: 265 A) o continued each day except for “break” on July 2 –quench history: 182 A, 211 A, 214 A, 218A, 229 A  steady progress but have once again run out of cryogens  waiting for new supplies (hopefully Tuesday) to continue training Issues —shield is cooling, but very slowly (even with LN assist) o down to ~115K now, still need LHe top-ups —power supply controller is finicky o not bipolar, so slow discharge (unacceptable) o dump circuit likely to quench magnet o gets “lost” if parameters input incorrectly o only operates properly at low ramp rate (~1 A/min) PS not ready for prime time

4. July 6, 2009MICO:Zisman4 Quench at 229 A Disperses He rather impressively

5. July 6, 2009MICO:Zisman5 Plans Continue with magnet training to reach 265 A or beyond Evaluate power supplies to assess their usability —replacements would be expensive and also take substantial floor space Decide on need for additional cooling circuit for shield on magnet 1 Continue work on magnet 1 —about 2 months behind magnet 2 at present