Jefferson Lab Weekly Briefs
April 15, 2009
12 GeV Upgrade
Yesterday, April 14, the official groundbreaking ceremony for the 12 GeV CEBAF Upgrade project was accomplished with great success in spite of the rain. The ceremony was held on the Hall D Complex construction site adjacent to the tunnel connection to the existing accelerator enclosure. The ceremony was attended by national, state, and local politicians, DOE Office of Science and local representatives, local university representatives, former Jefferson Lab directors, and many Jefferson Lab staff and users. Video of the 12 GeV Upgrade Groundbreaking Ceremony is now available online.
The construction contractor for the CHL Building addition, Ritchie-Curbow, started worked last week. Workers installed silt fence for erosion control, relocated the fire hydrant and prepared the aggregate subbase for the expanded asphalt pavement on the east side of the CHL Building. The constructor is scheduled to complete the paving and guardrail installation this week. CEBAF Boulevard is scheduled to be closed on April 20.
The scheduled accelerator down has started to wrap up. Continuous wave beam (130uA) from Gun2 was restored to the injector inline dump. Gun3 vacuum chamber was baked. Commissioning of cryomodules NL12 and SL07 continued. The new beam switchyard raster magnet was installed. Other general maintenance work continued. Preparations for construction of the Central Helium Liquefier building addition started.
Free-Electron Laser (FEL)
FEL staffers are making small upgrades and fixes to the FEL while work to repair/replace the low-conductivity water feed goes on. At present, the FEL is still working toward coming back up May 18.
In a recent paper (arXiv:0904.1586 [hep-lat]), a novel method was successfully demonstrated for the first time to calculate the electric polarizabilities of charged hadrons with lattice QCD. This work, made possible by an allocation at the High Performance Computing Center at Jefferson Lab, is the first in a series aimed at calculating the low-energy electromagnetic structure of hadrons, from pion and kaon polarizabilities to the nucleon (and hyperon) magnetic moments, polarizabilities and spin polarizabilites. A comparison between first-principles calculations of these quantities with the measured hadronic structure from low-energy Compton scattering experiments will then be possible, in particular a comparison to the anticipated results from COMPASS at CERN and HIGS at TUNL.
The survey and alignment group performed a control survey of a portion of the accelerator network. This consisted of sparsely spaced points around the circumference of the accelerator and not the entire set of monuments. The results agree well with surveys carried out last summer, where the laser tracker was used in the accelerator (which did measure all the monuments) and a conventional above-ground surface control survey. The greatest standard error is approximately 1 part in 2.5 million, with an average standard error of 1 part in 4.5 million for this latest survey. As a reference, typical land survey standard error is 1 part in 50,000 and traditional 1st order national geodetic survey accuracy is 1 part in 600,000.
JLab's Safety Numbers
100 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Environment, Safety, Health & Quality
Highway work zone safety is especially important as JLab begins construction for the 12 GeV Upgrade. According to EHS Today, there are three work-zone fatalities and 160 work-zone injuries per day.
Road work is necessary for providing safe and efficient transit, although road-work zones often seem nothing more than an inconvenience to motoring public, which can lead to irritable, quick tempered, irrational behavior and emotions. Many times, the only thing that is protecting a pedestrian and a work-zone employee are painted stripes, cones or barrels.
Some safe practices when entering work zones, including those at Jlab, are:
Check Out the Latest Montage
Last Chance to Register for JLab's "Biggest Loser" Contest
National Library Week: April 12-18
Don't Forget to Register for AVS Dinner/Student Poster Session
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