Jefferson Lab Weekly Briefs
November 23, 2011
12 GeV Upgrade
Beam tests of the first two installed 12 GeV cryomodules are complete, and the in-tunnel performance data is being reviewed. The cryomodules and the associated new radiofrequency zones are being used successfully for delivering beam to the experimental halls. Testing is underway of the first-article high-order mode filters that will be placed into the waveguides of some of the accelerating cavities. The cryogenics group is preparing to receive the 4.5K coldbox and the warm compressor skids in the next weeks.
In Hall C, preparations for the resumption of the Q-weak experiment were completed and the high-power, liquid-hydrogen target was cooled and refilled. After beam tuneup, collaborative checks and detector checkout, a set of low-current tracking runs was started. This tracking data is used to determine the kinematics at which the Q-weak asymmetry is measured. This will be followed by resumption of high-current, parity-production running.
Toward the end of the Six-Month Shutdown, Hall C staff began the removal of the lead panels that line the inside of the Short Orbit Spectrometer detector hut. The full disassembly of the SOS spectrometer will be carried out after the end of 6 GeV operations.
Accelerator steer up and the optics restoration and finalization procedure were completed. Fourth-pass beam was extracted to Hall B and second-pass beam was extracted to Hall C. As much work on failed radiofrequency circulators was completed as was allowed by available parts; the remaining circulators will be repaired when parts are available. Collaborative checks with the halls were completed prior to physics beam delivery. Hall C had various problems with the Q-tor magnet, the most disruptive of which was a leak that resulted in the hall low-conductivity water system conductivity rising to an out-of-spec level. This disrupted beam delivery in both halls for about a day. Recovery allowed resumption of beam to Halls B and C.
Center for Theoretical and Computational Physics
A new paper investigates short-range nuclear forces in the framework of chiral effective field theory. It was previously known that the singular attraction of one-pion exchange could enhance nucleon-nucleon contact interactions, exceeding the expectation based on naive dimensional analysis. Using renormalization group invariance as a constraint, this article discusses how the enhancement propagates to higher orders and what modification must be made to the famed Weinberg's scheme for chiral nuclear forces.
JLab Calendar of Events
Nov. 24-25: Thanksgiving holiday; JLab closed
Environment, Safety, Health and Quality
The Story of the Feral Cat
JLab personnel should never attempt to handle or feed wild animals onsite. The lab has a contract with a pest control service, which has qualified personnel for safely removing wild animals from the premises. With winter coming, many animals and insects are seeking a warm winter home. If you are aware of any such critters that need to be removed from JLab, contact Mike Lewellen at x7169.
Computing and Networking Infrastructure
Internet Outage Scheduled for Dec. 6
Personal Dosimeter Change Out Set for Dec. 19
Annual Reminder to Review Withholding Exemptions
Tracking Thomas at JLab
Congratulations this week go to Narciso Gomez and DeAnn Maddox, who were the first to correctly identify the Nov. 16 location. Honorable mentions go to Ryan Bodenstein, Ron Bartek, Samika Hawkins, Whit Seay, Karen Bartek and Dick Owen. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.