12 GeV Upgrade
Excellent progress continues to be made on the work planned for the shutdown period. All dipole magnet rework and re-installation into the arcs has been completed. Checkout of the first 12 GeV cryomodule, C100-1, is near completion. In the early stages of that checkout, a new CEBAF record of 22 Megavolts per meter was set for a phase- and amplitude-locked cavity in the tunnel. Since then, all cavities have been operated simultaneously at 18 MV/m. Refinement of the RF control algorithms is proceeding. Six cavities have been phase and amplitude locked at 15 MV/m simultaneously, which will improve as the resonance control algorithms are refined. The second new radiofrequency zone is almost ready for powering the second new cryomodule, C100-2, when it arrives in the tunnel. Testing of C100-2 is underway in the Cryomodule Test Facility.
In Hall A, the target platform arrived and was installed. The local beam dump should arrive soon. Installation for the g2p experiment is basically on track.
The holiday made for a short week last week. RF pedestal mounting and magnet shim checks were completed. Commissioning was suspended for the holiday but resumed Tuesday. Tuner work on 2L24, work on the MCC air conditioning system, and low-conductivity water system work continues. LCW system water is now circulating in the beam switchyard, and the north linac has been filled and the water is cycling for deoxygenation. The MYA archiver has been restored. The road between the North Linac Service Building and the MCC is closed to allow trench work required to hook Hall D to the MCC electronic equipment room.
This week, the FEL team made a cathode and re-established beam in the machine, using it to check the new components in the injector region.
Center for Theoretical and Computational Physics
In a recent paper, the axial couplings of mesons and baryons containing a heavy quark have been calculated using lattice QCD. These couplings determine the leading interactions with pions in heavy hadron chiral perturbation theory and are central quantities in heavy quark physics, as they control strong decay widths and the light-quark mass dependence of heavy hadron observables. Using these results, the strong decay widths of Σb(*) baryons have been computed, finding agreement with recent determinations by the CDF collaboration at Fermilab, and upper bounds have been presented for the decay widths of the Ξb′(*) baryons.
The RF group has supported SRF in commissioning the first C100 cryomodule installed in the tunnel. The RF team also has been commissioning the second RF system, zone SL25, into waveguide shorts and continuing RF installation in three other south linac zones. Much work has been done on calibration, data collection and system optimization for these first two 12 GeV RF systems, while the other three zones are worked on. Both the DC Power and Instrumentation and Controls groups have been busy preparing Hall A for the g2p experiment to run in the fall and restoring systems in the accelerator that were disturbed during 12 GeV installation or machine maintenance. The Personnel Safety System group re-certified the south linac protection system in August, completed other upgrades and performed maintenance activities. The EES Support Group has spent much of the summer fabricating sub-assemblies used by all the other EES groups. Electricians within the support group have been involved in a myriad of infrastructure upgrades that go along with new 12 GeV installations. These include power outages, cable pulls, cable tray work, and installation or modification to AC services for accelerator equipment.
Environment, Safety, Health and Quality
Cuts, Lacerations and Punctures
The nature of the work at JLab is often very hand-intensive, and many of the materials used present sharp edges or thin protrusions. JLab provides a variety of gloves to protect workers' hands. When approaching a task, workers should review their safety equipment, including any gloves that they have, to make sure the equipment is appropriate for the task. If a different type of glove is needed or other equipment is needed, the worker should contact the Stockroom to obtain the appropriate equipment.
Computing and Networking Infrastructure
CNI Maintenance Period Planned
Onsite TIAA-CREF Counseling Offered
American Red Cross Blood Drive
Lost and Found
Tracking Thomas at JLab
Congratulations to Jason Willoughby, David Fazenbaker, Linda Ceraul, Ron Bartek and Tonya Evans, who were the first to correctly identify the Sept. 7 location. Honorable mentions go to Michelle Shinn, Jodi Patient, Doug Higinbotham, Sue Witherspoon, Stephen Wood, Rob Mahurin, Paul Reimer, Lisa Kaufman, Ryan Bodenstein, Lori Zukerman, Harry Fanning and Marty Hightower. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.
JLab Calendar of Events
Sept. 26: Safety Shoe Vendor onsite