Jefferson Lab Weekly Briefs
November 30, 2011

Physics

Hall A is preparing for a possible beam commissioning run to start on Dec. 12, pending the successful completion of the installation in Hall A. This will be minus the polarized proton target, but will allow commissioning and debugging of several new systems on the beamline, as well as the detector systems. Hall A is also finalizing a project management plan for the Super BigBite projects.

In Hall C, the Q-weak experiment completed tracking measurements, made the transition to high-current running and recommissioned the apparatus. With good-quality beam at currents up to 180 microamps, the experiment sees main detector performance as good or better than the first Q-weak run. The beamline is now instrumented with new digital beam current cavity electronics developed by the Electrical Engineering Systems group. The new electronics essentially eliminate electronic noise on the measurement of beam current as a source of uncertainty for the Q-weak measurement. The experiment is also enjoying excellent performance of the Compton Polarimeter, a result of electron detector maintenance and improvements in laser power over the Six-Month Shutdown.

Accelerator

The week started with high-current tuning to the Hall C beam dump. Optics corrections were made to the machine where needed to get ready for the long holiday weekend of beam delivery. There were some difficulties at first in achieving high-current delivery. After some radiofrequency zones were turned off and the orbits were re-tuned, the accelerator performed excellently during the majority of the extended holiday, with the maximum beam current of 180 microamps being delivered to Hall C and up to 30 nanoamps to Hall B. Hall B ceased taking beam on Monday to change out the target, a process expected to take up to two days.

Center for Theoretical and Computational Physics

QCD tells us that a quark knocked out of a proton violently is nevertheless still entangled with the proton through its phase, an intriguing concept that is thought to explain why the so-called Sivers asymmetry observed in semi-inclusive deep-inelastic scattering experiments at JLab and elsewhere is not zero. To check if gauge link operators representing the "phase history" of the quark are responsible for the observed strength of the Sivers asymmetry, nonperturbative methods, such as lattice QCD, are required. A new paper demonstrates that lattice calculations of Sivers observables and related quantities are indeed possible, even if challenging, and presents first results extracted on the JLab computer cluster from existing configurations from the LHPC and MILC Collaborations.

Engineering

The Electrical Engineering Systems DC Power group took delivery of the first 12 GeV Magnet Power Supply last week. Fifteen more power supplies are due as part of the 12 GeV Upgrade in the present procurement cycle. The alignment group measured the photon pipe that runs from the Hall D tagger enclosure to Hall D; this pipe is 50 meters long. Additionally, the Survey and Alignment group measured a 12 GeV CLAS12 Region 2 Drift Chamber end plate in the clean room. This plate was measured in multiple loading configurations to check for deformation and deflection. The Mechanical Engineering group (Magnet Measurement) continues to measure/inspect the new magnets for the 12 GeV spreader and recombiners.

Facilities Management & Logistics

There will be a power outage for much of the JLab campus during the winter holidays/shutdown days, from 5 a.m. Friday, Dec. 23, through 6 p.m. Sunday, Jan. 1. The power outage is necessary for several planned maintenance and construction activities. The following facilities and areas will be locked and inaccessible during the power outage:

  • Test Lab (Building 58)
  • CTF (Building 57)
  • Building 59
  • EEL (Building 90)
  • CEBAF Center (Building 12)
  • Trailers 34D and 34E
  • Central Materials Storage Area (CMSA)
     

Power is scheduled to be restored and systems back online for normal operations starting at 7 a.m. on Monday, Jan. 2. The power outage will not affect the ARC, VARC, Buildings 13 and 19, Guard Post 2, the RadCon buildings and trailers or the Accelerator Site. More information regarding preparations for the shutdown power outage will be available on Insight in the coming weeks. For questions regarding the power outage, contact Paul Powers.

JLab Calendar of Events

Dec. 5: Safety Shoe vendor onsite
Dec. 10: JAG Children's Holiday Party
Dec. 19: Safety Shoe vendor onsite
Dec. 21: Colloquium and Public Lecture, CC auditorium, 4 p.m.
Dec. 23-Jan. 1: Winter holidays/Shutdown days - JLab closed
Jan. 11: Hall D Open House

Environment, Safety, Health and Quality

Walking Surfaces & Cold Temperatures
Everyone is well aware that cold weather conditions can create slick walkways and roads, making slips, trips and falls all-too-frequent occurrences. This recently happened at JLab. Over the Thanksgiving holiday, a worker at one of JLab’s construction sites slipped on some frost. The worker fell backward and struck their head, losing consciousness for a short period and resulting in a visit to the emergency room (the worker was released after an examination).
 
The lesson to learn: Even though the air temperature may be above freezing, watch for wet, shaded and surfaced areas that may harbor areas slippery from dew or frost. Always be mindful of where you walk and try to anticipate the presence of slick areas.

Computing and Networking Infrastructure

Internet Outage Scheduled for Dec. 6
Access to offsite internet sites will be unavailable beginning at 5 p.m. on Dec. 6, while the external router is being upgraded. The down is expected to take an hour, and onsite access will not be affected. For more information, contact the Helpdesk at x7155.

Computing Services Outage Will Precede Shutdown Power Outage
The Information Technology division will conduct maintenance on equipment in the Computer Center. JLab computer account holders will not have access to any central computing services from 5 p.m. Thursday, Dec. 22 (when the holiday shutdown begins) through 8 p.m. Friday, Dec. 23. Services that will be offline include: JLab's public website; lab email; printers; calendars; access to central file services, such as the J, K, L and M drives; home directories; group areas; and all MIS and business services applications.

Note that because outages of the central computing systems are rare and there are dependencies on electric work, the time needed to restore all systems to normal operations is only an estimate.

Many systems across the lab do not recover from a central services outage without human intervention. Work center supervisors and/or building custodians who have essential systems that require human intervention to restore should make arrangements with Facilities Management & Logistics before the holiday break begins. FM&L contacts include:
Paul Powers, electrical systems: ph. 876-1780
Carroll Jones, HVAC systems: ph. 876-1778
Dave Kausch, fire protection and facility access systems: ph. 876-1187

Once computing services are re-established, individuals should be able to access most computing services, including email accounts, remotely/from home during the remainder of the holiday break. For additional information about the Computer Center outage, contact the IT Division Helpdesk, x7155, before the holiday shutdown begins.

Announcements

Mobile Mammography Unit Onsite Next Wednesday
Appointments are still available for the Sentara Mobile Mammography Unit that will be at JLab on Dec. 7. Click the link to book your appointment now. Mammography detects breast cancer, and The American Cancer Society recommends scheduling your first or baseline mammogram by age 40. It only takes 15 minutes! This service is open to all; personal health insurances will be billed.

Annual Children’s Holiday Party Set for Dec. 10
The Jefferson Activities Group is hosting a Children's Holiday Party on Saturday, Dec. 10, 10 a.m.-1 p.m. in the CEBAF Center lobby. All children of JLab employees, contractors and users are invited. Youngsters may talk with Santa Claus, take part in games and craft activities, and enjoy light snacks. All children must be accompanied by an adult. Each family is asked to bring a new, unwrapped toy donation for Toys For Tots. For more information, visit the JAG website.

Volunteers Needed to Help With Children’s Party
A number of volunteers are needed to help with the Children's Holiday Party, mostly as crafts table and game helpers. Volunteers are needed to assist younger children with basic cutting, gluing or tying. Volunteers are also needed for the snack area and as Santa's Helpers. Sign up online.

Toys For Tots Toy Drive Underway
As in years' past, JLab is participating in the U.S. Marine Corps' annual Toys For Tots toy drive. Bring in your donation of new, unwrapped toys for children ages 1-12 and deposit them in the collection boxes located near the main entrances of CEBAF Center, VARC, ARC, Test Lab and the MCC. The deadline for bringing in donations is noon Saturday, Dec. 10.

Holiday Office Door/Cubicle Decorating Contest Underway
Ready, set, hang those decorations for the JAG Holiday Office Door/Cubicle Decorating Contest. Prizes will be awarded for the Best Decorated, Most Original and the Silliest. For more information, visit the JAG website.

Personal Dosimeter Change Out Set for Dec. 19
JLab's semi-annual personal dosimeter change out will take place during the afternoon of Monday, Dec. 19. This includes the dosimeters of all JLab staff, users and subcontractors. If you need to use your dosimeter during the change out period on Dec. 19, you may exchange it that morning in the Radiation Control Dosimetry Office in Bldg. 52B, Room 4, 8 a.m. -1 p.m. If you have questions, contact Becky Mosbrucker, x7236.

Tracking Thomas at JLab
Little Thomas is visiting all corners of the JLab campus. If you can identify his location this week, email Kandice Carter with your guess. Guesses are accepted through Friday.

Congratulations this week go to Stephanie Vermeire, who was the first to correctly identify the Nov. 23 location. Honorable mentions go to Michelle Shinn, Jodi Patient, Steve Wood and Doug Higinbotham. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.