Jefferson Lab Weekly Briefs
October 27, 2010
12 GeV Upgrade
The North and South Access Building additions and power upgrades to support the accelerator operations at 12 GeV are complete. Ready-for-equipment (RFE) inspections were conducted on Oct. 14 and 25, including representatives from 12 GeV management, Facilities Management & Logistics and ESH&Q. The cooling towers and pumps for the Central Helium Liquefier utility upgrades are set in place, and the subcontractor is installing the associated piping. Metal wall panels for Hall D were delivered to the site on Oct. 25, and installation will commence this week. Accelerator group welders are completing the leak test on the portion of the beam pipe entering into the photon beam dump at Hall D.
In Hall C, the pump that circulates liquid hydrogen in the Q-weak target stopped turning and failed to restart. The target was removed from the scattering chamber, and examination of the pump revealed that one of two bearings failed. In addition to repairing the pump with a different type of bearing, this event is being used as an opportunity to make minor improvements and repairs to the target.
Q-weak commissioning has continued productively without a target, focusing on tuning parity beam feedback systems, studying backgrounds and commissioning the Compton polarimeter. In an important milestone, the polarimeter has now observed an asymmetry in the scattering of laser photons off of the electron beam.
The accelerator was running well, with low trip rates. On Friday, Hall A beam was changed from pass 5 to pass 4. On Saturday evening, the west arc lost power briefly, which affected beam delivery for about one and a half hours. In addition, the Hall C line may have 500 Hertz noise vertically, which the experts have been investigating.
The FEL team was limited in running last week by vacuum issues in the injector, but the team was able to take power data on the laser to begin to resolve discrepancies in power measurements between several meters.
Center for Theoretical and Computational Physics
In a joint Excited Baryon Analysis Center-Hall B paper <arXiv:1010.4555>, the relations between the multipole amplitudes and all possible 16 spin observables of pseudoscalar meson photo-production reactions are established. It is found that presently available hyperon photo-production data determine only bands of solutions that are far from the precision needed to extract nucleon resonances. The importance of a new generation of ongoing experiments underway in Hall B to measure all 16 spin observables is emphasized.
JLab Calendar of Events
Oct. 28: JAG/JSA Oktoberfest, 3-6 p.m.
JLab's Safety Numbers
58 Days since Last Recordable Accident (JLab record: 331)
Environment, Safety, Health & Quality
Halloween is a fun time for kids, but it is also an important time to be extra vigilant for possible safety hazards so that your children have a fun and safe holiday. Click the link for timely tips from the U.S. Product Safety Commission to keep your little trick-or-treaters out of harm's way.
Computing and Networking Infrastructure
Introduction to Mailman for List Owners/Administrators
Discontinuation of Dial-up Modem Pool (RAS) Service
CNI Maintenance Day
Volunteers make this event possible. If you haven’t yet signed up to help, visit the JAG Oktoberfest volunteer page and sign up today. Just one hour of your time helps immensely.
Sentara Mobile Mammography Unit Onsite Dec. 6
Pet First-Aid Class