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12 GeV Updates

18 January 2017

In-place assembly and testing are proceeding on Hall C's three newest superconducting magnets in the Super High Momentum Spectrometer (SHMS). The Q2 quadrupole magnet has reached 106 percent of the current required for the maximum SHMS momentum (11 GeV/c). Stable operation for 11 GeV/c physics has been demonstrated, and final acceptance tests are underway. Welding of the cryogenic helium pipes between the dipole magnet and its service can has been finished and leak-checked, and the first-pass weld of the nitrogen lines is done. The dipole helium circuit has passed its pressure test. Leak-checks of the Q3 magnet vacuum system are underway. Pressure-testing of the Q3 helium and nitrogen circuits will come next. At the same time, connection and checkout of the Q3 and dipole instrumentation systems are moving forward.

With all but one of the SHMS detectors in place, a cosmic-ray trigger has been set up to collect signals from the detectors and exercise the data-acquisition hardware and the event-reconstruction software. Stands for the beam pipe downstream of the recently installed target are in place, and much of the vacuum pipe has been erected. Limit switches and wiring to allow remotely controlled rotation of the SHMS is being prepared.

12 January 2017

The Torus magnet for CLAS12 has been parked at a temperature of 80 Kelvin for the past two months awaiting the upcoming beam run in Hall B. t will be brought back down to liquid helium temperature at the end of January to prepare for the run. The drift chambers have all been suspended from the Torus cryostat and had their services attached, and the Forward Carriage has been rolled upstream to its operating position next to the Torus.

The five coils of the Solenoid magnet have now been spliced into one continuous circuit, and the resulting magnet "cold mass" has been covered with reflecting aluminum foil. The radiation shields are now being fit to the outer circumference of this assembly. After this step, the multi-layer insulation blankets will be added and then the entire assembly will be suspended inside the cryostat outer shell; eight suspension links are welded to the cryostat and then attached to the cold mass by insulating links in this step. The conical end regions and the bore tubes of both the radiation screen and the cryostat were prepared earlier and will be attached after the cold mass is suspended from the cryostat outer shell in order to close the cryostat. Planning for shipping the Solenoid to Jefferson Lab is well underway, including the final steps in the design of the shipping cradle and isolation springs needed for the road trip to Virginia.

4 January 2017

As the 12 GeV upgrade project nears the commissioning phase for Halls B and C, the last of the scheduled modules of the Accelerator Readiness Review (ARR) is scheduled for Jan. 9 and 10. The ARR committee is charged with determining if Jefferson Lab is prepared to deliver beam for the commissioning and operation of Experimental End Stations (Halls) B and C, and the experimental equipment associated with the 12 GeV Upgrade Project, in a safe and efficient manner. To this end, both halls are continuing with the installation of the remaining magnets, detectors, beamline components and associated infrastructure/services.

In Hall B, the Central Time of Flight has been placed on the mock-up support stand, and installation is underway. Hall B also continues working the various detectors' gas delivery systems and remaining utilities. Hall C has installed the beamline supports and continues with hookup of the Q3 and dipole magnets.