Jefferson Lab Weekly Briefs December 12, 2007
Jefferson Lab Weekly Briefs
December 12, 2007
Site Power Outage
The Test Lab electrical substation will be taken offline over the holiday break to replace aging equipment. The power outage will begin at noon on Friday, Dec. 21. The following buildings will be without power: EEL, Test Lab, CEBAF Center, Buildings 31, 33, 52, 54, 57, & 59, Rad Con Trailers 52A, B, C, Trailers 34A, 34B, 34D & Safety Trailer (35). Electrical power will remain off in these buildings until Dec. 31. No one will be allowed in these buildings until after 8 a.m., Jan. 1, 2008. For additional information, please see the website or contact Paul Powers at ext. 7258.
12 GeV Upgrade
The 100 percent design package for the 12 GeV North and South Access Building Additions was completed by the JLab Facilities Design Team. The package has been distributed for an internal design and safety review, and a meeting to discuss the review findings is scheduled for Dec. 17. Advance Procurement Plans for the 12 GeV Civil Construction FY09 Procurements related to the CHL Building Addition and the Hall D Complex have been developed. The initial procurement effort will be Sources Sought notices to identify interested vendors. The Sources Sought notice for the Hall D Complex is scheduled to be issued in Spring 2008.
In Hall A, the Coulomb Sum Rule experiment, E05-110, has been taking production data. It was interrupted this week for two days to replace the defective transformer in the power supply of the second quadrupole of the left High Resolution Spectrometer. Production running remains characterized by a multitude of short runs at different spectrometer momentum and angle settings and beam energies for a variety of targets.
The week started with continued beam to all three halls. There were some problems encountered with various radio-frequency devices, due to low-conductivity cooling water temperature becoming unregulated and dropping several degrees. On Dec. 5, Hall A requested a pass change, which went well. An energy change on Dec. 8 took more time, due to Hall C current limitation investigations. For the most part, the accelerator ran very well, with 240 hours of beam delivery distributed among the three experimental halls.
Free-Electron Laser (FEL)
This week, FEL staff successfully applied high voltage to the gun in the test stand, ramping initially to 85 keV without incident. This important achievement is the culmination of activities ranging from conventional construction and facilities, sophisticated personnel and equipment protection systems, a very high-voltage power supply requiring a large sulfur hexafluoride system, extreme high vacuum, critical modifications to the gun design, preparations for the laser to produce the electron beam and an advanced computer remote control system. New mirrors have now been installed and are under vacuum in the high-reflector and output-coupler vacuum tanks. The center wavelengths of the three narrow-band mirrors in each cassette are 0.93, 1.2, and 2.8 microns. The additional space has a broadband mirror. A very advanced ONR-funded apparatus for pulsed laser deposition (PLD) was installed in FEL Lab 5 by the company that provided the equipment.
In the paper arXiv:0712.1214 [hep-lat], Theory Center staff have computed, for the first time in lattice QCD, certain weak nuclear couplings of the Sigma and Xi hyperons, which have not yet been measured experimentally. In addition, using the corresponding coupling of the nucleon, the effects of the breaking of "SU(3) flavor" symmetry, which relates the couplings of these baryons, has been estimated. The results indicate around a 20% symmetry breaking, with about 5% statistical and systematic errors.
JLab's Safety Numbers
84 Days since Last Recordable Accident (JLab Record: 319)
JLab Calendar of Events
Dec. 13: Quark Cafe Holiday Lunch Buffet
Environment, Safety, Health & Quality
With the mild weather that we are enjoying this week, it is hard to believe that severe winter weather driving conditions are just around the corner. Here are some National Safety Council winter driving safety tips:
Computing and Networking Infrastructure
Scientific Computing Outage
Network Outage Dec. 21
Site Power Outage Ramifications
ORNL Visitor Information Hacked
Winter Feast at the Quark Cafe
End-of-year TLD badge change out nears
Holiday Pie Orders Taken Through Dec. 14
Ready, Set, Decorate!