Jefferson Lab Weekly Briefs
February 15, 2012
Hall A is in the final stages of preparing for the g2p experiment, which will hopefully begin in two weeks. The polarized proton target is being cooled down (thanks to the work done by the target group). The HARP scanners have been refurbished and are being installed. The beam position monitor hardware is complete, but is awaiting the firmware and EPICS control. A local dump is being prepared and will be installed. The septum magnets will have shims to increase the magnetic field. The installations continue this week and into next week. Following a final alignment, the hall will be ready for beam.
In Hall C, Q-weak continued production data taking on hydrogen until problems in the dump developed. When beam is resumed, Q-weak plans several days of asymmetry measurements with a transversely polarized beam.
JSA/JLab Graduate Fellowship Program
JSA/JLab Sabbatical Support Program
The Injector group associated with the PEPPo experiment reported initial success in setting up the beamline and getting beam transported most of the way down it. Halls B and C received great beam delivery all week and through the weekend until Hall C experienced a problem with a beam dump detector system. The new radiofrequency modules in the South Linac, SL24 and SL25, were brought online and provided RF power to the beam without major interruptions. This is a major accomplishment for JLab!
This week, a leak on one of the RF windows on FEL03 was successfully mitigated by the installation of a second window and buffer vacuum. A new gun cathode was prepared, installed on the load-lock and baked. The Darklight collaboration installed a sealed sodium iodide detector in the FEL vault after calibrating it in Lab 1. The detector is for a study of background radiation levels. On Friday, the group executed a major cleanup of building 18, preparing space for future new projects.
Center for Theoretical and Computational Physics
The structure functions f(x), g1(x), and g2(x), measured in deep inelastic scattering, were recently calculated using a constituent quark model of the nucleon based on the covariant spectator theory. The model assumes the nucleon can be described by a covariant three-quark wave function which is a superposition of S, P and D-state components. Both the shape of the wave function and the relative strength of each angular momentum component are determined by fitting the experimental DIS structure functions, and it is found that a model with a large D-state component (35 percent) can explain all of the proton and neutron data. The work suggests that the famous proton spin puzzle might be replaced by another puzzle: What is the dynamical origin of this large D-state component?
The alignment group has been very busy. Recently, it has completed a Hall D photon dump berm elevation survey, continued to fiducialize and align the g2p components as they become available and fiducialized cryomodule C100-4. In addition, the group has located new horizontal and vertical monuments in between the Tagger area and Hall D; these will be used for rapid connection surveys between the main accelerator and Hall D as there is no direct line of sight available. In magnet measurement, work continued to measure the dipoles for the 12 GeV spreader/recombiner magnets. These consist of some difficult magnets with curved pole tips and more traditional dipoles with linear pole tips. The group also finished mapping the Moller Quads in place in Hall A.
Environment, Safety, Health and Quality
OSHA Releases Latest Occupational Hazard Numbers
JLab's 2012 Benefits Open Enrollment Is Now Available
Feb. 15 Colloquium Canceled
Golf League Forming for Season
New Bike Club Jersey in the Works
Calling All Design Fashionistas!
Tracking Thomas at JLab
Congratulations this week go to Maurizio Ungaro, Paul E. Reimer, Annie Tran, DeAnn Maddox, Karen Bartek, Stephanie Vermeire, Doug Higinbotham, Michael Haddox-Schatz, Brita Hampton, Casey Heck, Samika Hawkins, who were the first to correctly identify the Feb. 8 location. Honorable mentions go to Michelle Shinn, Brian Carpenter, Kim Kindrew, Lori Zukerman, Dick Owen, Lawrence Ferbee, Tim Whitlatch, Dipangkar Dutta, Jason Willoughby, Huan Yao, Mark Ito, Stephen Wood, Ryan Bodenstein, James Maxwell, John Leckey, Anusha Liyanage, Dena Polyhronakis, Buddhini Waidyawansa, Rob Mahurin, Dan Moore, Anna Cornejo, Harry Fanning, David Jenkins, Tammy Frye and Elaine Zuchowicz. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.
JLab Calendar of Events
Feb. 27: Safety Shoe vendor onsite