Jefferson Lab Weekly Briefs
June 8, 2011
12 GeV Upgrade
At the request of the DOE Office of Nuclear Physics, the director of the Office of Project Assessment, Daniel Lehman, convened a Mini-Review of the 12 GeV Upgrade Project via teleconference on June 1. The panel was charged with evaluating the overall status of the project with particular focus on Hall B and responses to recommendations from the December 2010 review. The committee concluded that the project is progressing appropriately and the team is focused on the necessary Hall B subsystem issues. Recommendations were made regarding an update to the spend plan and scheduling the next full review in the October 2011 timeframe.
Hall A has been de-installing the former experiment apparatus and preparing for the fall run. The technicians have removed the BigBite spectrometer, the target and parts of the beamline. It's a long process, but the work is proceeding at a good pace.
The third week of the six-month accelerator shutdown went well. The cables and CAMAC cards for the viewers and beam scrapers for the injector (PEPPo) project were in place. Removal and installation of west arc dipoles continued. The seven refurbished dipoles of Stack 1 (2A01) were installed and the alignment was underway. The microphonic and vibration measurements on superconducting radiofrequency cryomodule R100 were finished and the module was moved to 2L23. SRF cryomodule C100-1 was installed at 2L21, and the cooldown was started. W2 and W4 CAMAC to VME conversion was in progress; VME crate, modules and cables for iocwa4 were installed. Many other tasks were continued or started.
The FEL team spent the week dealing with leaky valves in the injector and planning a procedure that would allow replacement of the gun without endangering the cryounit booster.
Center for Theoretical and Computational Physics
It has been known since the 1960's that the exchange of vector mesons (such as rho, omega and phi) plays a prominent role in the nucleon elastic form factors at momentum transfers below ~1 GeV2. The idea of "vector meson dominance" can now be formulated rigorously in QCD, using the concept of transverse charge densities in a fast-moving nucleon. A recent dispersion analysis reveals that the transverse densities at distances b ~ 1 femtometer are maximally sensitive to vector meson exchange and quantifies the corrections from higher-mass exchanges. These results provide fresh insights into the nucleon's partonic structure and suggest new ways to study the couplings of vector mesons and their excited states in electron-scattering experiments.
Work on the 12 GeV beam transport in the accelerator's west arc is progressing better than anticipated. The installation group has removed 77 of 112 west arc dipoles from the tunnel. Twenty-one arc dipoles have been completely refurbished and had their respective H-Steel added. Magnetic measurements have been completed on six of the refurbished H-style arc dipoles. These six refurbished dipoles have been placed back in the beamline.
Five south linac warm region girders have been removed from the tunnel. These five girders have been reconfigured on the new 'short' style girders that are necessary to accommodate the upgraded cryomodules and are ready to be reinstalled.
Support for the Hall A g2p experiment has included the demolition of the impacted sections of beamline. This work has been completed. Additional activities have begun with the survey and drilling of the new stands which will support the g2p beamline.
Environment, Safety, Health and Quality
The guidelines emphasize that chest compression alone is valuable, even without rescue breathing. The target compression rate is approximately 100 per minute and the target compression depth is approximately two inches. When available, automated external defibrillators, or AEDs, are critically important and should be used as soon as possible.
Semi-Annual Personal Dosimeter Change Out Set for June 29
Tracking Thomas at JLab
Congratulations to Christopher Williamson, who was the first person to correctly identify the June 1 location. Honorable mentions go out to Elaine Zuchowicz, Tonya Evans, Karen Bartek, David Fazenbaker, Jim Follkie, Dennis Merritt, Connie Adams, Jason Willoughby and Allison Lung. 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
June 6-8 Users Group Workshop and Annual Meeting
JLab Summer 2011 Education Calendar
May 31- June 17: Hampton University Graduate Studies