Jefferson Lab Weekly Briefs
January 11, 2012
12 GeV Upgrade
The Hall D Complex facilities have been accepted from the construction contractor. Approval for occupancy of the Counting House, Service Building and Tagger Area is expected to happen in a few weeks, following completion of various tasks related to safety and janitorial services.
In Hall C, the Q-weak experiment resumed data taking, starting with yield measurements on a dilute gas in the target cell to determine the target cell window thicknesses. The experiment is now part way through the low current tracking measurements that are used to determine the experiment kinematics. Once these are completed, Q-weak will return to asymmetry measurements at the maximum possible beam current. During the last week, the laser for the Compton polarimeter was repaired, and a burst water-cooled power lead (connecting the Qtor magnet and power supply) was replaced. The Hall C Users meeting is set for this Friday and Saturday, Jan. 13-14, in CEBAF Center Room F113.
Last week was dominated by restoration of the accelerator and the halls following the break. Radiofrequency recovery included the repair of many cavities in the period between the termination of beam in December and the beginning of the winter down. This allowed the accelerator to be configured to the same energy with fewer passes, a necessity for the present lineup of hall experiments. Injector studies were performed in support of the Hall C Q-weak experiment. C100 studies continued during beam studies. Low-conductivity water leaks in both the accelerator and the halls required an interruption of beam delivery to repair. Tuesday beam studies time was used to swap LCW pumps in the end stations and to improve beam optics to Halls B and C. Higher-pass beam optimization, necessary for future running with Hall A, was also performed.
Theoretical and Computational Physics
In a recent Theory Center paper, the evolution of transverse momentum dependent distributions (TMDs) is applied for the first time to observables. The Sivers transverse single spin asymmetry is calculated and compared at different scales using the TMD evolution equations applied to previously existing extractions. Recent COMPASS measurements from CERN are shown to be consistent with the suppression prescribed by TMD evolution, and some predictions are given for future experiments.
The Machine Shop is presently manufacturing or continuing to manufacture:
The shop has processed 200 job requests since Nov. 7.
JLab Calendar of Events
Jan. 16: Martin Luther King Day holiday - JLab closed
Environment, Safety, Health and Quality
Computing and Networking Infrastructure
CNI Maintenance Day Set for Tuesday, Jan. 17, 5-7 p.m.
Brief Phone Outage Scheduled for Thursday, Jan. 12, 5-5:30 p.m.
Science Series Lecture: Volcanoes in Virginia!
New Dog Training Class Forming
Onsite Blood Drive Set for Jan. 27
Tracking Thomas at JLab
Congratulations this week go to Karl Slifer, Samika Hawkins, Harry Fanning, Jim Follkie and Doug Higinbotham, who were the first to correctly identify the Jan. 4 location. Honorable mentions go to Ryan Bodenstein, Pashupati Dhakal, Mike Dickey, Dick Owen, Mike Martin and Michelle Shinn. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.