Jefferson Lab Weekly Briefs January 18, 2012
Jefferson Lab Weekly Briefs
January 18, 2012
12 GeV Upgrade
Progress continues on the superconducting magnets and related infrastructure for Hall C. Winding of the coils for the Q1 quadrupole magnet for the Super High Momentum Spectrometer has started. A coil for the HB magnet was tested in a liquid helium dewar to more than 3,000 Amps of current. The copper stabilizer for the superconducting cable for the Q2, Q3 and dipole magnets has been re-shaped with the "keystone" and is ready to be soldered to the several kilometers of SSC cable. All sections of the support structure are under contract, with first sections already arrived at JLab. The five cryogenic control reservoirs are complete at the vendor and are undergoing acceptance testing. Bids are in hand for the several hundred tons of Q2, Q3 and dipole magnet yokes.
Hall A had a readiness review for the g2p/GEp experiments. The review covered technical and safety aspects. The experiments appear to be on track for starting on Feb. 15. The main remaining task is the preparation of the polarized proton target, a job which is being done by the target group (Chris Keith et al.).
In Hall C, the Q-weak experiment completed low-current tracking measurements and is now taking asymmetry data on the liquid hydrogen target using beam currents up to 180 microamps.
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JSA/JLab Graduate Fellowship Program
JSA/JLab Sabbatical Support Program
Most of the week consisted of sending low-current beam to Halls B and C. On Thursday, a spin dance was performed to optimize the spin polarization for Hall C. The injector was set up for higher current on Friday. The ultimate goal was weekend running at 180 μA to Hall C, but the remaining low-current operations in Hall C limited setup to 150 μA. Over the weekend, the last 30 μA proved difficult to obtain at times due to fleeting instabilities in the injector. At one point, a vacuum valve closed in the west arc, which required an access for replacement of an air line. Following the access, two arc dipole power supplies would not turn on and two radiofrequency cavities required bypassing. Once those issues were fixed and the accelerator was recovered, the optical setup in Hall B proved unsatisfactory for the hall. Once again, personnel were called in to assist and were able to make adjustments to get by until Monday. With the needed final correction of Hall B optics and elusive injector instabilities at high current, this week is going to be a challenging one.
Center for Theoretical and Computational Physics
JSA/JLab Distinguished Theory Student Fellowship Program
After extracting a spectrum of nucleon and Δ states from lattice QCD computations, a new analysis identifies a subset whose internal structure appears to be more complex than simply three quarks in relative motion. These hybrid baryon states feature an excited gluonic field that seems to be of the same chromomagnetic form as was found in hybrid mesons. The methodology leading to this conclusion is discussed and the implications for existing models of gluonic excitations are presented.
Environment, Safety, Health and Quality
Science Series Lecture: Volcanoes in Virginia!
New Dog Training Class Forming
Onsite Blood Drive Set for Jan. 27
Tracking Thomas at JLab
Congratulations this week go to Brita Hampton, Annie Tran and Doug Higinbotham, who were the first to correctly identify the Jan. 11 location. Honorable mentions go to Christiana Grenoble, DeAnn Maddox, Casey Heck, Eric Diggs, Mike Martin, Stephanie Vermeire, Robert Martin and Marcy Stutzman. 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
Jan. 23: Safety Shoe vendor onsite