Jefferson Lab Weekly Briefs
October 19, 2011
A DOE review for Hall A's Super BigBite projects was held last Thursday and Friday. This was a science, technical, cost and schedule review. The main conclusion is that staffers need to improve and update the project management plan, with a deadline of Jan. 3. For the g2p experiment, the target group is still trying to fix the superconducting magnet for the polarized proton target. The group is consulting with engineers and experts to formulate a solution to the shorts between the magnet coil and ground.
The power outage for repairs at SA-PP3 was successful. Control calibration of the low-conductivity water systems has been completed. Beam was established to the 5 MeV region as the accelerator began the process of starting up. Most of the south linac radiofrequency system has been turned on and is being stabilized. A small fire event in the north linac damaged two magnets; an investigation into the cause is proceeding. Meanwhile, planning of repairs and actions needed to prevent any similar events in the accelerator is well underway.
Due to lack of funds, the FEL has been put in stasis until such time as the program has funds to operate again. With a few exceptions, most of the staff have found homes in other JLab activities until January. Staffers will continue to work at a low level on Joint Technology Office activities and, when money comes in soon, on the Boeing FEL-Innovative Naval Prototypes program support effort.
Recently, the ratio of neutron to proton structure functions was inferred from a phenomenological correlation between the strength of the "nuclear EMC effect" and inclusive electron-nucleus cross sections at parton momentum fractions x>1. A new paper shows that, within conventional models of nuclear smearing, this extraction constrains the size of nuclear effects in the deuteron, suggesting important nucleon off-shell corrections in the deuteron structure function. The analysis determines the resulting proton d/u quark distribution ratio to be well below the SU(6) symmetry limit of 1/2, but significantly above the scalar diquark dominance limit of 0.
JLab Calendar of Events
Oct. 18-20: DOE Project Review of the 12 GeV Upgrade
Environment, Safety, Health and Quality
Laser Pointer Safety
At JLab, new pointers must be reported to the Laser Safety Officer, x6381. Pointers may only be Class 1 or 2 visible lasers of less than 5 mW with a yellow caution label. Class 3 or 4 lasers are not permitted for use as pointers.
Here are a few safety guidelines from the Laser Institute of America:
Computing and Networking Infrastructure
Major Systems Outage on Friday, Dec. 23
JLab Colloquium and Public Lecture Today
Informal Reception to Honor JLab's Founding Director, Hermann Grunder
Tracking Thomas at JLab
Congratulations this week go to Jason Willoughby, Debra Brand, DeAnn Maddox, Andy Kowalski, Ryan Bodenstein and Doug Higinbotham, who were the first to correctly identify the Oct. 12 location. Honorable mentions go to Narciso Gomez, Dick Owen, Michelle Bailey, Mike Wilson, Russell Mammei, Dennis Merritt, Brita Hampton, John Kelly, Cindy Eller and Ron Bartek. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.