Jefferson Lab Weekly Briefs
October 19, 2011

Physics

A DOE review for Hall A's Super BigBite projects was held last Thursday and Friday. This was a science, technical, cost and schedule review. The main conclusion is that staffers need to improve and update the project management plan, with a deadline of Jan. 3. For the g2p experiment, the target group is still trying to fix the superconducting magnet for the polarized proton target. The group is consulting with engineers and experts to formulate a solution to the shorts between the magnet coil and ground.

Accelerator

The power outage for repairs at SA-PP3 was successful. Control calibration of the low-conductivity water systems has been completed. Beam was established to the 5 MeV region as the accelerator began the process of starting up. Most of the south linac radiofrequency system has been turned on and is being stabilized. A small fire event in the north linac damaged two magnets; an investigation into the cause is proceeding. Meanwhile, planning of repairs and actions needed to prevent any similar events in the accelerator is well underway.

Free-Electron Laser

Due to lack of funds, the FEL has been put in stasis until such time as the program has funds to operate again. With a few exceptions, most of the staff have found homes in other JLab activities until January. Staffers will continue to work at a low level on Joint Technology Office activities and, when money comes in soon, on the Boeing FEL-Innovative Naval Prototypes program support effort.

Theory Center

Recently, the ratio of neutron to proton structure functions was inferred from a phenomenological correlation between the strength of the "nuclear EMC effect" and inclusive electron-nucleus cross sections at parton momentum fractions x>1. A new paper shows that, within conventional models of nuclear smearing, this extraction constrains the size of nuclear effects in the deuteron, suggesting important nucleon off-shell corrections in the deuteron structure function. The analysis determines the resulting proton d/u quark distribution ratio to be well below the SU(6) symmetry limit of 1/2, but significantly above the scalar diquark dominance limit of 0.

JLab Calendar of Events

Oct. 18-20: DOE Project Review of the 12 GeV Upgrade
Oct. 19: Colloquium and Public Lecture, 4 p.m., CC auditorium
Oct. 24: Safety Shoe vendor onsite
Oct. 25: Reception Honoring Hermann Grunder's Contributions, Birthday
Oct. 25: Science Series public lecture
Nov. 1: Science Series public lecture
Nov. 2: JAG Beam Kickoff Tailgate Picnic
Nov. 3: Annual E-Commerce Small Business Vendor Fair
Nov. 6: Daylight Saving Time ends
Nov. 7: Safety Shoe vendor onsite
Nov. 24-25: Thanksgiving holiday; JLab closed

Environment, Safety, Health and Quality

Laser Pointer Safety
A typical laser pointer has long been limited to 5 milliwatts of output power, which is powerful enough for indoor use, yet relatively safe. However, high-power laser pointers in a rainbow of colors can be found online. These devices can emit as much as 1,000 mW of power, 200 times that needed for safe use. In addition, some of these pointers may also emit invisible and dangerous radiation at many times the stated visible light power.

At JLab, new pointers must be reported to the Laser Safety Officer, x6381. Pointers may only be Class 1 or 2 visible lasers of less than 5 mW with a yellow caution label. Class 3 or 4 lasers are not permitted for use as pointers.

Here are a few safety guidelines from the Laser Institute of America:

  • Never shine a laser pointer at anyone - laser pointers are designed to illustrate inanimate objects;
  • Do not allow minors to use a pointer unsupervised;
  • Do not point a laser pointer at mirror-like surfaces; and
  • Do not purchase a laser pointer if it does not have a caution or danger sticker on it identifying its class.

Computing and Networking Infrastructure

Major Systems Outage on Friday, Dec. 23
The CNI group is planning a major computer systems outage for the first day of this year's winter holiday break. On Friday, Dec. 23, 6 a.m.-5 p.m., all major systems will be unavailable, including email, calendar and access to central file services, such as the J:, K:, L: and M: drives, home directories, group areas, etc. Additionally, all MIS applications and business services applications will be unavailable. All services will return to full operation by 5 p.m. For additional information, contact the IT Division Helpdesk, x7155.

Announcements

JLab Colloquium and Public Lecture Today
Come learn about "The Path to Fusion Energy and the Princeton Plasma Physics Lab" in a colloquium presented today in the CEBAF Center auditorium at 4 p.m. Presented by M.C. Zarnstorff, deputy director for research at PPPL, the lecture will address the enormous progress made in our understanding and ability to control high-temperature plasma confined by magnetic fields, including applications for the ITER experiment.

Informal Reception to Honor JLab's Founding Director, Hermann Grunder
JLab is celebrating the contributions and achievements of its founding director on the occasion of his 80th birthday. All staff, on-site users and friends are invited to join in recognizing the man who transformed the original concept for CEBAF from a modestly designed, medium-energy accelerator into a world-leading, precision superconducting machine capable of delivering an unparalleled nuclear physics research program. The celebration will begin at 3:30 p.m., with cake and light refreshments to follow, in the CEBAF Center atrium on Tuesday, Oct. 25.

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 Fridays.

Congratulations this week go to Jason Willoughby, Debra Brand, DeAnn Maddox, Andy Kowalski, Ryan Bodenstein and Doug Higinbotham, who were the first to correctly identify the Oct. 12 location. Honorable mentions go to Narciso Gomez, Dick Owen, Michelle Bailey, Mike Wilson, Russell Mammei, Dennis Merritt, Brita Hampton, John Kelly, Cindy Eller and Ron Bartek. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.