Jefferson Lab Weekly Briefs November 25, 2009
Jefferson Lab Weekly Briefs
November 25, 2009
12 GeV Upgrade
Using the short accelerator shutdowns in January and July 2010 is critical for the success of the 12 GeV installation work planned for the six-month down, which includes up to five commissioned cryomodules in the South Linac and machining/refurbishment of the west arc dipole magnets. The 12 GeV installation activities for the January 2010 down include radiofrequency waveguide installations and cryomodule base plate swaps. The 12 GeV installation work for these two downs is reviewed, approved and coordinated with existing activities through teamwork with 6 GeV operations personnel and the use of existing work planning tools.
In Hall C, removal of the hypernuclear experiment E05-115 and installation of Q-weak continues. The High Resolution Kaon Spectrometer and High Resolution Electron Spectrometer shield houses are being disassembled, and the custom beamline chicane has been removed. The beamline upgrade to accommodate a Compton polarimeter is underway. The beamline downstream of the green wall has been removed, and a new platform that will support beamline elements and the Moller polarimeter is being installed in the hall.
Overall, the accelerator was running well with high current (110uA) to Hall A and low trip rates. At one point, beam was running for more than an hour without any interruption. There were some hardware issues, which have been resolved. Several devices were replaced: a cooling water hose of zone 1L04, the hunt adder MAN5R04 power supply, some faulty parts in zone 0L04, and the vacuum valve 2L12A position indicator.
The high reflector can for the Ultraviolet FEL was put under vacuum for the first time. The FEL team ran injector and drive laser tests and also made important strides in the operation of the control systems for the UV and infrared lines, which is critical for efficient UV commissioning. The team continued efforts for the JLAMP proposal to be submitted to DOE Basic Energy Sciences in mid-December.
Seven of the eight magnetic moments for the baryon octet (nucleons, Λ, Σ and Ξ) have been measured, and attempts to explain them using flavor SU(3) symmetry have long been a topic of interest. In a paper just submitted <arXiv:0910.2171 [hep-ph]>, JLab theorists used these experimental numbers, together with SU(3) symmetry and the covariant spectator theory, to make a model-independent estimate of the size of the pion cloud corrections to these moments. The results indicate that the pion cloud contribution to the nucleon magnetic form factors at zero momentum transfer is about 40 percent, considerably larger than many previous estimates.
JLab's Safety Numbers
6 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Nov. 26-27: Thanksgiving holidays - JLab closed
Environment, Safety, Health & Quality
While wet leaves, mud and wet surfaces tracked into buildings add an additional burden for maintaining safe working surfaces, these same conditions can make safe driving a challenge - especially in rural areas. Wet leaves that have accumulated on the roadway are extremely slippery, making the driving conditions similar to driving on ice. Besides reducing the car’s traction, causing skidding and the possibility of losing control of the vehicle, leaves often cover the painted road markings, making it difficult to know the locations of the lanes. Here are a few reminders for driving on slick, wet or icy roads:
New Additions to Property Manual
Mobile Mammography Unit Onsite
'Tis the season for E-Card Scams
Get Ready for the Holidays!
JLab Key Validation Continues