Jefferson Lab Weekly Briefs
January 26, 2011
12 GeV Upgrade
All but two of the 86 niobium cavities for the cryomodules are on site, which is sufficient for all 10 of the new 12 GeV cryomodules, plus four spare cavities. Assembly of the first cavity string is complete and its installation into the first cryomodule has begun. All 36 four-meter dipole magnets for the beam transport lines have been received and testing is underway. All beam transport quadrupole magnets have been received and have passed their field quality, field strength and magnetic-vs-physical-center tests. Construction of the Central Helium Liquefier expansion’s coldbox is proceeding according to plan. Progress on the expansion of the Personnel Safety System to include the 10 new linac zones plus Hall D continues.
In Hall C, Q-weak is continuing production data taking. The high-power liquid hydrogen cryotarget is operating reliably at 150 microamps and above, with cooling power to spare. The Qtor power supply has seen more stable operation, possibly due to the placement of additional shielding around the supply. A donut shield has also been added around the beamline to reduce already small backgrounds in the main Q-weak detector (quartz bars).
JSA/JLab Graduate Fellowship Program
JSA/JLab Sabbatical Support Program
The accelerator was running with some downtime. Last Tuesday, the pre-buncher amplifier was replaced, which stabilized the high current to Hall C. The alignment of the injector chicane beamline was also corrected. On Saturday, the injector and the north linac were opened up for the U.S. Particle Accelerator School tour. The End Station Refrigerator tripped on Sunday and the Central Helium Liquefier tripped on Monday. Beam delivery was resumed on Monday.
The FEL team is hosting a two-week course called “Beam Measurements, Manipulation and Instrumentation at an ERL FEL Driver" through the U.S. Particle Accelerator School. The course is comprised of 12 students, and they are given the opportunity to make beam-based measurements and also learn about beam diagnostics with separate laboratory exercises. All is proceeding extremely well in the control room, the lab and the vault, and the team worked on the lab’s holiday on Monday to get a full program in.
Theoretical and Computational Physics
In a new paper <arXiv:1101.2165 [hep-ph]>, a model for generalized parton distributions (GPDs) is discussed that allows one to "implant" into GPDs the Regge behavior of the usual parton distributions at small momentum fractions of the nucleon carried by the parton. An essential element of the model is the form of the parton-hadron vertex. If such a vertex has a non-pointlike, wave function-type form, the resulting GPDs are shown to be free of singularities at the border point between the parton-like and wave function-like regions, contrary to earlier claims.
Environment, Safety, Health and Quality
Moves and relocations during the coming months may reveal old containers of chemicals that are no longer needed or may have expired. Generally, this is not an issue when the label is intact and you want to dispose of it; contact the JLab Hazardous Waste team for assistance: Brett Lewis, x6254, or Jennifer Williams, x7882.
If you discover an unlabeled and unknown container, check with your co-workers to see if it is theirs and help them get a proper label on it. If still not identifiable, then call the Hazardous Waste team for assistance. Under no circumstances should an unknown chemical container be dropped off or left without notification or prior communication with a team member.
Computing and Networking Infrastructure
JLab_guest Wireless Change On the Way
Onsite TIAA-CREF Counseling Offered
Want to Play Softball?
Colloquium: Nanotubes - 20 Years and Into the Future
Results from Blood Drive
JLab Calendar of Events
Jan. 27: Protect Your Identify: The Newest Identity Theft Scams