Jefferson Lab Weekly Briefs
July 2, 2008
12 GeV Upgrade
Final preparations are ongoing for the upcoming DOE Independent Project Review scheduled for July 22-24. As one of the requirements, extensive drawing packages to support the mature engineering and design of the various 12 GeV systems have been generated. Earlier, a series of eight design and safety reviews of various physics equipment were completed, with the last two in May emphasizing the Halls B & D complete system designs and the Hall C support structure and shield house interim design. The review committees were complimentary on all presentations and the mature status of the present designs and had no further recommendations.
In Hall C, the proton polarimeter that was used for the GEp/GMp experiment has been removed from the High Momentum Spectrometer focal plane. The polarimeter has been replaced by the standard HMS detector package, which will be used for the next experiment in Hall C.
The investigation of the Dominion Power event (last week's Briefs) led to changes in the controls of the supply and return valves at the Standby Refrigerator (SBR) to prevent warm gas from being sent into the SBR. The bakeout of the Gun 2 diagnostic cross went well. Transformer maintenance continued making progress. A glycol cooling line for the South Access Building was damaged during excavation; while repairs were done quickly, short-term higher temperatures in some buildings could not be avoided. An extensive overhaul of the 30 Hz system and a series of Personnel Safety System power supply maintenance tasks were completed. The structural steel construction of the General Purpose Building continued.
Non-trivial relations between time-reversal odd transverse momentum dependent parton distributions (TMDs) and impact parameter generalized parton distributions (GPDs) were conjectured recently in the literature. The relations have been shown to hold exactly in lowest order diagrams in so-called spectator quark models. A new model-independent analysis (arXiv:0805.3165 [hep-ph]) classifies the common "mother functions" of GPDs and TMDs for a spin-0 hadron — so-called Generalized TMDs (GTMDs) — and shows that the Boer-Mulders function and the corresponding chirally odd GPD for a spin-0 hadron do not originate from a common mother function, which in turn does not support a model-independent exact relation between these.
The DC Power group has been busy performing maintenance and interlock wiring checks on all the magnet power supplies. Verification of the wiring and schematic updates to include field changes that have accumulated over the years will improve safety, facilitate diagnostics, correct problems and ensure faster repair times when the accelerator resumes operation. Viewer and inline dump conversion to VME (a computer bus standard) from the old CAMAC bus in building West Arc 5 has been delayed due to "old software" conversion issues. All other diagnostic systems are moving forward as planned. The Vacuum and Installation group has installed a group of eight quadrupole magnets in the Free-Electron Laser ultraviolet line. The Alignment group is in the process of aligning these quadrupoles.
JLab's Safety Numbers
261 Days since Last Recordable Accident (JLab record: 319)
Environment, Safety, Health & Quality
If your holiday weekend plans include barbecue, boating or other fun-in-the-sun activities, don't forget to slather on the sunscreen. According to the U.S. Centers for Disease Control and Prevention, skin cancer is the most common form of cancer in the United States. Of the most common skin cancers, melanoma is the most dangerous, and more than half of all melanomas are caused by exposure to ultraviolet (UV) light.
Here are some quick tips from the CDC on easy ways to protect yourself from the sun's UV rays:
Computing and Networking Infrastructure
Networking Changes in CEBAF Center
Here is the schedule for upcoming changes:
Individual machines may be registered here at any time by using a web browser on that machine. If you are unsure about your machine registration, it is OK to register again. Please contact the HelpDesk, x7155, about other registration-related queries.
Additional Summer HelpDesk Hours
CNI Systems Maintenance Planned
JLab Calendar of Events
July 4: Independence Day Holiday (JLab closed)