Jefferson Lab Weekly Briefs
May 11, 2011
12 GeV Upgrade
The 2011 six-month shutdown starts on Friday, May 13. The 12 GeV project installation schedule has been integrated into the lab-wide schedule. All transportation and material-handling equipment to support the effort is on site. The 12 GeV Upgrade project goals for the shutdown include the civil construction breakthrough of the northeast section of the tunnel; civil construction of the beam switchyard addition, including the two new penetrations to the tunnel; low-conductivity water upgrades to support magnets, box power supplies and new radiofrequency zones; removal, refurbishment and re-installation of west and east arc dipoles; arc 10 installation of the new four-meter magnets and girder assemblies; installation and commissioning with beam of two new C100 cryomodules in the south linac; installation of new RF zones in the linacs; and upgrades to the safety system.
Hall A successfully completed the "x>2" experiment on Sunday morning, and then made a configuration change to give the few days before the six-month shutdown to the short-range correlations experiment to complete its running on helium-4. During the past week, the accelerator performed very well, delivering 17 to 19 Coulombs of charge per day for combined Hall A and C high-current running.
In Hall C, production data taking on the liquid hydrogen target has continued with beam currents between 150 and 180 microamps. A number of auxiliary measurements/test plans have also been carried out, including background studies, tracking measurements to characterize detector response and a detailed study of the Moller polarimeter performance. The Q-weak collaboration is hosting an "End-of-First-Run" party this Friday, 2-6 p.m. in the SURA Residence Facility.
Research Assistantship Nominations Due May 31
CEBAF has been keeping up its momentum, delivering beam of high current and high quality to Halls A and C with 82.4 percent of beam availability. Hall B was down due to installation of HDice. Last week was another record week, with 18.9 Coulombs extracted from the injector in a 24-hour period. During beam studies, data were collected for optics and future C100 RF modules. On Tuesday, the ion chambers of the Hall C beam dump failed, which prevented Operations staffers from delivering high-current beam to the hall. The system experts quickly resolved the issue and beam delivery was resumed. On Sunday, Hall A was changed from 3-pass to 4-pass for the SRC experiment.
The FEL ran well at high (multi-kilowatt) power levels for many hours for the 2.2 micron optics tests, with minimal trips. Terahertz calorimeter experiments also yielded good results, and the team is preparing for the final week of running before shutting down until July.
Theoretical and Computational Physics
A new review article <arXiv:1105.0951> summarizes the role of two-photon exchange in electron-hadron scattering. The effects of TPE on various observables are described, including proton and neutron form factors e+p to e-p cross section ratios, electroproduction of resonances and pions, and nuclear form factors. In the weak sector, the role of TPE and γZ interference in parity-violating electron scattering is discussed, together with their impact on the extraction of the strange form factors of the nucleon and the weak charge of the proton.
The Electrical Engineering RF group is working on final preparations for the start of the six-month shutdown. Three more 12 GeV klystrons were delivered last week, along with one more cathode power supply. By the time the May klystron delivery is complete, there will be enough klystrons available to populate the first new RF zone. The three cathode power supplies now installed are more than enough to meet the RF zone installation plans for the summer down. First article card cages for the new RF klystron pedestals have been delivered as well. The low-level RF test stand for calibration of RF control modules is undergoing final checkout and an RF zone commissioning cart is being assembled. The Master Oscillator drive line extension in the north linac was tested and is now ready for connection to the main drive line during the down.
Environment, Safety, Health and Quality
Visiting Construction and 6-Month Shutdown Work Areas
For instance, the waist-high orange construction mesh barriers and warning signs denote areas that may require additional training or an escort, require specific personal protective equipment and entail a daily job hazards briefing. Certain locations will immediately "stop work" when untrained or improperly protected people enter the site. This stoppage will cause a delay, with an accompanying significant management response.
To keep everyone on task and you and your coworkers safe, never enter an area that is unfamiliar to you without first ensuring that you have the necessary training to enter that area. Always heed all hazard warning signs, as the work conditions in some areas may rapidly change. If you are not directly involved with the work in a particular area, stay out of the area and watch from the safe side of the fence or barrier. Never enter areas that are active work zones unless you have specific business with the job and are properly trained and equipped.
Computing and Networking Infrastructure
Upcoming Changes to all Windows Systems at JLab
The solution that JLab is adopting is "PowerBroker for Windows Desktops" by BeyondTrust. Using this new tool, all Windows systems will be reconfigured so that users don't need to log in with administrative privileges to get their work done. This tool does for Windows what "sudo" does for Linux, allowing Windows users to work a lot like Linux users normally do. Making this change allows the Computer Center staff to address some specific concerns (such as browser plug-in security problems) and to adopt a "principle of least privilege" policy that is consistent with industry best practice and specific guidance from DOE. The system is being tested, and the details of the deployment plan are being worked out now. An initial round of systems will be configured with PowerBroker on the upcoming maintenance day (May 24). The tool will be deployed on all Windows systems by September. For more information, see the Computer Center website or contact Marty Wise.
Tunnel Access Requires Completing Two-Part Training
Check Training for Shutdown Activities
Onsite TIAA-CREF Counseling Offered
Tracking Thomas at JLab
Congratulations to David Fazenbaker who was the first person to correctly identify the May 4 location. Honorable mentions go out to Brad Cumbria and Steve Covert. 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