Jefferson Lab Weekly Briefs
August 27, 2008
12 GeV Upgrade
The Beam Transport team continues measurements of both prototype beamline quadrupole magnets with the goal of optimizing certain design features such as the end-chamfer. The end-chamfers are small bevels on the ends of each of the magnet’s four poles and are used to minimize the amount of magnetic field errors not associated with fabrication or assembly errors. Determination of the end-chamfers for the "QP" style magnet is underway and is nearly complete for the "QR" style magnet. The Request For Proposals (RFP) was released for the 4-meter arc dipole contract.
The installation of the polarized 3He target in Hall A is proceeding smoothly. The field mapping of the three pairs of Helmholtz coils mounted on the pivot and of the BigBite magnet has been successfully completed. Cosmics tests of the new gas Cherenkov detector for BigBite have demonstrated that it is operating to specifications. The installation of the new electron detector for the Compton polarimeter, designed by the University of Clermont-Ferrand, is underway with technical support from Clermont-Ferrand.
Preparation of Hall B for the next DVCS (deeply virtual Compton scattering) run is in progress, repairs to CLAS have been completed; electronics for the DVCS inner calorimeter are under installation. The new SiPM hodoscope is in final tests before installation of amplifier boards. Repair work on Cherenkov sector 1 is almost complete.
Injector: The 500ua (microamps) test run was successfully concluded. A combined peak current of 930ua was achieved. A mirror for remote gun switching has also been installed.
Connections to the C50-6 cryomodule at NL11 are progressing at an efficient rate, including hooking up the waveguides. Painting of the electrical substations on the accelerator site has been finished.
Free-Electron Laser (FEL)The FEL gun vacuum bake is well underway and proceeding smoothly. All sextupoles are now installed in the infrared beamline. Installation of the ultraviolet beamline has been proceeding well; all dipoles, quads and sextupoles are in and the system is getting ready for pump down. FEL staff held a Kickoff Review for its Joint Technology Office efforts in Energy Efficiency and Ring Resonators.
A relativistic quark model of the nucleon and Δ (1232), where only the lowest orbital angular momentum states (L=0) are considered in the quark-quark pair, was recently used to estimate the electric and magnetic distributions of the Δ (arXiv:0807.2922 [hep-ph]). Since the Δ is the first excited state of the nucleon, knowledge of its electromagnetic structure is very important in nuclear physics; however, its physical proprieties are largely unknown due to its unstable character. It lives for a very short time before decaying to other hadrons. The results of the model are consistent with the scarce experimental information available, and with the magnetic dipole distribution estimates based on lattice QCD (quantum chromodynamics), although it predicts a higher charge concentration than that in lattice QCD.
JLab's Safety Numbers317 Days since Last Recordable Accident (JLab record: 319)
662 Days since Last Lost Workday Accident (JLab record: 662)
JLab Calendar of Events
Aug. 27: 3 p.m. Colloquium: Fermilab Plan with an Intensity Frontier Accelerator; Young-Kee Kim, Deputy Director, Fermilab
Environment, Safety, Health & Quality
JLab implemented a web-based Lessons Learned Program (http://coe.jlab.org/ll/) in early June. The site is similar to others throughout the Department of Energy complex, allowing each lab or facility a central location for researching safety topics while conducting work planning or task hazard analysis.
School Back in Session Soon: Be Safe Around Buses
Tee'em up for the JLab 2008 Fall Golf Tournament!
Directions to the course from JLab: When leaving JLab, turn right on Jefferson Avenue and go 14.2 miles. Williamsburg Country Club is on the right.
Please make checks payable to Danny Machie. The entry deadline is Friday, Oct. 3. Contact Machie, x7501, for more info.
JLab welcome picnic for new Director Hugh Montgomery
An RSVP request will be distributed by e-mail later this week.
TIAA-CREF Retirement Counseling Sessions
United Way School Tools Drive Ends Sept. 5