Jefferson Lab Weekly Briefs February 9, 2011
Jefferson Lab Weekly Briefs
February 9, 2011
12 GeV Upgrade
The construction contractor for the North and South Access low-conductivity water upgrades, D.E. Kirby of Portsmouth, Va., mobilized last week. Silt fencing is in place and excavation for the cooling tower foundations will begin this week, weather permitting. The 5 MVA unit substations for the Central Helium Liquefier #2 compressors were delivered and were set on the concrete pads last week. The pump startup and commissioning of the cooling towers, which provide the condenser water to the compressors, is expected to commence within the next two weeks.
After improvements in beam quality and reliability, Q-weak has been taking production data on the liquid hydrogen target with very high efficiency. Sufficient data has been acquired to determine that the measured asymmetry is non-zero and of the expected sign. While a much larger amount of data is required to obtain the proposed precision, this gives confidence in the experimental equipment, data acquisition electronics and analysis software. In addition, a significant amount of data with an aluminum target was obtained. This data will be used to subtract backgrounds from the aluminum windows of the LH2 target.
The accelerator has been running well since Friday. On Friday, it was found that the root cause of the injector instability was a misbehaving radiofrequency cavity (0L03-2) in the injector. After lowering the gradient of the cavity, Operations staffers were able to send 150 microamp beam to Hall C with very good halo counts. Also during the investigation of the beam instability, the injector optics were changed, and beam appears to be better.
The FEL group spent last week performing optical transport upgrades to get ultraviolet FEL light to user labs and prepared for upgrades of the Laser Personnel Safety System for UV use in the labs. The staffers also plan to upgrade several communication links to vacuum hardware
Theoretical and Computational Physics
One fascinating aspect of strong interactions is that the internal structure of hadrons measured in scattering experiments is in a subtle way related to the excitation spectrum seen in hadron-antihadron creation/annihilation processes. Using such "dispersion relations," theorists have calculated the transverse charge density in the pion from the precise data on the e+e- → π +π- process collected at e+e- annihilation facilities. The resulting spatial image of the pion reveals a pointlike quark-antiquark configuration at the center, which represents its fundamental particle content in QCD and can be probed in high-momentum-transfer pion production experiments at Jefferson Lab.
JLab Calendar of Events
Feb. 9: Nanotubes Colloquium and Public Lecture
Environment, Safety, Health and Quality
Workplace Noise May Double Risk of Heart Disease
Computing and Networking Infrastructure
New Mathematica and Maple Versions Available in CUE
Redhat Enterprise Linux 6 Now Available in CUE
Colloquium: Nanotubes - 20 Years and Into the Future
Celebrate V-Day with the Amoré (Quark) Cafe
Tech Notes Now Reside in Docushare
Plan Your JLab Tour Now
Onsite TIAA-CREF Counseling Offered