Jefferson Lab Weekly Briefs
August 13, 2008
12 GeV Upgrade
The horizontal-bend magnet is the first superconducting magnet of Hall C's Super High Momentum Spectrometer. Its location close to the beamline introduces special design constraints, such as small size and heat dissipation. JLab is collaborating with the National Superconducting Cyclotron Lab (NSCL) at Michigan State University on the design development. Recently, collaborators at the NSCL began a trial wind of a magnet coil to demonstrate that the cable can be bent around sharp edges, and the first turn has been successful.
The installation of the polarized 3He target is proceeding smoothly. The three pairs of Helmholtz coils mounted on the pivot are in the process of being field-mapped. The new gas Cherenkov detector for BigBite is being tested with cosmics.
The LN1 transformer was removed by crane and trucked out for repairs. Temporary power has been hooked up until the transformer is re-installed after repairs. In the injector, Gun 3 was high-voltage conditioned, loaded with a new superlattice photocathode and then underwent a bake-out. The planned maintenance of the cooling towers for the North and South Access Buildings has been completed. System checks and cleaning of the RF low conductivity water (LCW) cooling circuits has been finished.
Free-Electron Laser (FEL)
Testing of the high-charge beam is proceeding on the gun test stand, and the FEL gun has been reassembled and is being prepared for installation in the vault. Assembly of the Advanced Energy Systems booster module is proceeding. FEL staff now has the first third of the ultraviolet beamline bolted together and all quad girders but two in the tunnel. Three of four advanced optical transport cans for high-power infrared are installed.
A semi-quantitative estimate of the prehadron production time based on recent preliminary HERMES data on hadron transverse momentum broadening in nuclear deep-inelastic scattering was presented in arXiv:0808.0656 [nucl-th] and confronted with preliminary CLAS data. Prehadrons are an intermediate stage of the struck quark fragmentation into observed hadrons, and their interactions with the target nucleus probe the space-time development of the fragmentation process. The obtained production time can explain the data well except for dependence on the photon virtuality, which remains a theoretical challenge: a few mechanisms that may contribute to its explanation are suggested, along with possible experimental tests.
JLab's Safety Numbers
303 Days since Last Recordable Accident (JLab record: 319)
JLab Calendar of Events
Aug. 12-14 Occupational Medicine Cholesterol Screenings
Environment, Safety, Health & Quality
Four High-Performance Work Teams (HPWTs) have been formed to address the findings from the recent HSS Review. These teams are cross-functional in nature and have representatives from across the facility. Facilitated sessions have begun for each, with a primary emphasis on root cause identification and the accompanying corrective action plans. Prevention of future similar issues is critical, thus the improvement plans will focus on site-wide, systemic improvements.
The four noted areas from the review are Material Handling, Assessments, Issues Management and Event Investigation and Reporting. Individual team work sessions will continue throughout the month of August, with each team providing a final plan by Sept. 5. The submissions involve only the plans and milestone dates; implementation dates will vary.
More information on the progress of these teams will be available in the coming months.
Computing and Networking Infrastructure (CNI)
HelpDesk Hours Are Changing
JLab Emergency Backup Website
JLab Adopt-A-Spot Event Needs Volunteers
Energy Secretary Delivers Address
JLab Mourns Death of Henry Whitehead
American Red Cross Blood Drive Results
Occupational Medicine extends a special thank you to those donors who patiently waited during the drive, as well as those who attempted to donate during the afternoon. There were some problems that caused a delay in the donation process. We apologize for any inconveniences this may have caused. Again, we extend a sincere thank you to everyone that participated and volunteered with this blood drive and to congratulate you for a job well done! Mark your calendars for the next blood drive on Oct. 7.
Christoph Leemann Retirement Reception