Jefferson Lab Weekly Briefs July 9, 2008

Jefferson Lab Weekly Briefs

July 9, 2008

12 GeV Upgrade

An R&D task to re-measure the Higher-Order Mode (HOM) damping in the 12 GeV-style superconducting radio frequency (SRF) cavities has verified last year’s results, i.e. the HOM damping meets the specification comfortably. The cavities have been removed from the Horizontal Test Bed and follow-on measurements in the Vertical Test Area have begun.    

Assembly of the first prototype beam transport quadrupole has been completed. Field measurements have begun.

The final specification needed for the procurement of the 4K coldbox was approved last week.


In the injector, 100 KeV characterization studies were performed. Preparations are underway for a bake out of gun 2, while gun 3 is being readied for running. Disassembly of the injector sync light monitor revealed some unpainted lead bricks. Proper procedures were followed after the discovery, including notifications to ESH&Q as well as Radiation Control prior to removal to a lead storage building. The standby refrigerator (SBR) tripped during the holiday weekend. Causes for this event are being investigated Construction continued on the structural steel building at the South Access Building.

Free-Electron Laser (FEL)

A number of magnet girders are being installed in the FEL Ultraviolet/amplifier beamline. The FEL gun is being prepared for reassembly and its support systems for recommissioning. There is also good news from SRF, where the string assembly of the 750 MHz Advanced Energy Systems booster was completed.


A quark-diquark model of the proton's structure was recently used in arXiv:0807.0323 [hep-ph] to calculate transverse momentum distributions (TMDs). When integrated over the parton's transverse momentum, TMDs reduce to the well-known parton distribution functions. The model calculation was used in particular to highlight what kind of information is contained in TMDs (e.g., related to partonic orbital angular momentum).


The Alignment group fiducialized the FEL collimator and turning mirror cassette (TMC) cans for the Optics group. The TMC is part of the optical transport system (OTS), which delivers beam to the user labs in the FEL complex. The Alignment group also completed positioning of all installed QX quadrapole magnets for the FEL UV line.

JLab's Safety Numbers

268 Days since Last Recordable Accident (JLab record: 319)
613 Days since Last Lost Workday Accident (JLab record: 613)

JLab Calendar of Events

July 8-10: DOE ES&H Inspection - Report Validation and Closeout
July 10-11: Teacher-to-Teacher Workshop at JLab
July 14-19: Lattice 2008
July 22-24: DOE Office of Science OPA Independent Project Review of the 12 GeV CEBAF Upgrade Project
July 22-25: Thin Film - Superconducting Radiofrequency Technology Workshop
July 30: American Red Cross Blood Drive
August 6: Colloquium: The Sustainable Energy Challenge
August 12:14: DOE Accelerator Safety Workshop
August 17-19: Lead Radius Experiment (PREX) Workshop
Sept. 1: Labor Day holiday: JLab closed




Environment, Safety, Health & Quality

On average, 62 people are killed every year by lightning in the U.S. Those who survive a lightning strike suffer from a variety of long-term, debilitating symptoms, including memory loss, attention deficits, sleep disorders, numbness, dizziness, stiffness in joints, irritability, fatigue, weakness, muscle spasms, depression and an inability to sit for long.

The National Weather Service offers these tips for lightning safety:

  • Watch for developing thunderstorms. Thunderstorms are most likely to develop on spring or summer days but can occur year round.
  • Seek safe shelter at the first sign of thunder. Lightning can strike as far as 10 miles from the area where it is raining. That's about the distance you can hear thunder. If you can hear thunder, you are within striking distance.
  • Minimize the risk of being struck. Most lightning deaths and injuries occur in the summer. Where organized outdoor sports activities take place, coaches, camp counselors and other adults must stop activities at the first roar of thunder to ensure everyone time to get a large building or enclosed vehicle.
  • If you are inside a building, stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity. Stay away from pools, indoor or outdoor, tubs, showers and other plumbing. Buy surge suppressors for key equipment. Install ground fault protectors on circuits near water or outdoors. When inside, wait 30 minutes after the last strike, before going out again.
  • If a person is struck by lightning, call 911 and get medical care immediately.


For more information on severe weather prcoedures at JLab, see the EH&S Manual.

Computing and Networking Infrastructure

CNI Systems Maintenance Planned
The CNI group is currently planning a systems maintenance day for July 15, from 5-10 p.m. All central services (such as e-mail, printing, and access to central directories, including group and home) will be unavailable until 6 p.m., while two network boards are replaced. Windows and Linux patches will be pushed out to all desktop systems. Please leave your system on overnight to receive the patches. Computer users may need to reboot their systems Wednesday morning to complete the installation. There will be additional computing outages during this time, so check the web pages at for details. If you experience any difficulties with your machine after you have rebooted, please contact the HelpDesk by e-mail or x7155.

Networking Changes in CEBAF Center Begin July 10
This summer, the CEBAF Center network is being changed to allow network ports to automatically recognize registered computers when they are connected. Users of unregistered computers may need to contact the HelpDesk for assistance on the day the changes go into effect in your area.

Here is the schedule for upcoming changes:
Thursday, July 10: CEBAF Center F Wing 2nd floor
Tuesday, July 15: CEBAF Center F Wing 1st and 3rd floors
Tuesday, July 22: CEBAF Center C Wing
Tuesday, July 29: The rest of CEBAF Center, including Wings A and B

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.



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