Jefferson Lab Weekly Briefs July 28, 2010


Jefferson Lab Weekly Briefs
July 28, 2010

12 GeV Upgrade

12 GeV tunnel installation tasks during the upcoming Summer 2010 accelerator shutdown include installation of cables in the new zones of the north and south linacs, magnet cable labels, 10 new floor pedestals for Hall D beam line girders, Arc 10 stands, waveguide hangers, low conductivity water (LCW) west arc headers, and extension of the north linac master oscillator. Lessons learned during this shutdown will be used to refine plans for installation work during the six-month shutdown starting in May 2011.


As part of an effort to coordinate the 12 GeV Project needs, the JLab facilities group is developing an on-line database for related space and storage requests including offsite rentals. Coordination of equipment for material handling and transportation continues in order to ensure installation activities are adequately supported to perform the work safely.


Over the last week, beam was delivered to Hall B for about four shifts. Hall A was down for installation. Hall B had issues with its target. Hall C continued to work on its target. The accelerator was available and was used for beam studies. The CHL tripped twice.

Free-Electron Laser

The first six UV optics have been installed and aligned, representing significant progress toward first lasing in this wavelength range.


After extensive installation activities - which finished ahead of schedule - the temporary wiggler chamber was reinstalled and pumped down, and electron beam recovered with good transmission through the cookie-cutter defining the wiggler chamber aperture. A short bunch (~300 fsec FHWM) was generated with this configuration.

Theory Center

Theory Center staff, in collaboration with researchers from Brazil and Australia, have studied a possible mass shift of the J/Ψ meson in cold nuclear matter <arXiv:1007.2220 [nucl-th]>. The J/Ψ mass shift arising from the modification of the D and D* meson loops at normal nuclear matter density is found to range from -16 MeV to -24 MeV under a wide variation of values of the cutoff masses. This can give insight into the partial restoration of chiral symmetry and QCD color van der Walls forces in the nuclear medium, and can be explored experimentally at JLab with the 12 GeV





American Red Cross Blood Drive
The American Red Cross Blood Drive is underway today, July 28, from 10 a.m.-4 p.m. in CEBAF Center Room F113. New and repeat donors are encouraged to attend. Walk-ins are welcome; donations have been low recently due to the weather. Volunteers are also needed to help with the blood drive. E-mail or call Johnie Banks, x7539, for additional information.


JLab Community Invited to Summer Interns Poster Session

High school and college interns that participated in JLab's summer science enrichment programs will share their experiences and projects during a poster session scheduled for Friday, July 30, from 11:45 a.m. to 1:30 p.m. in the CEBAF Center lobby. The entire JLab community is invited to stop in any time during the poster session. The six participants of the High School Summer Honors Program, and the 30 participants of either the Science Undergraduate Laboratory Internship or the Old Dominion University Research Experiences for Undergraduates programs, will present posters they developed based on their work or research projects.

August Beam Physics Symposium Honors Yaroslav Derbenev
On Aug. 2 and 3, Jefferson Lab will host an international event to celebrate a milestone for both a scientist and his half century in science. The lab is holding a Beam Physics Symposium to honor the 70th birthday and lifetime of achievements in accelerator and beam physics of Yaroslav "Slava" Derbenev, whose distinguished career stretches from Novosibirsk to Yerevan and from Ann Arbor, Mich., to JLab's Center for Advanced Studies of Accelerators. A special session recognizing Derbenev will take place from 4-5 p.m. on Aug. 2 in the CEBAF Center auditorium. The entire JLab community is invited to this portion of the symposium. For more information, contact Audrey Barron, x7327, or Yuhong Zhang, x7509.

JLab's Safety Numbers

12 Days since Last Recordable Accident (JLab record: 331)
134 Days since Last Lost Workday Accident (JLab record: 676)

JLab Calendar of Events

July 28: American Red Cross Blood Drive
July 30: Science Education Summer Poster Session
Aug. 2-3: Beam Physics Symposium
Aug. 5: Safety Shoe Vendor onsite
Aug. 20: Safety Shoe Vendor onsite

Aug. 23-25: PAC 36
Sept. 1: TEDF Groundbreaking Ceremony
Sept. 6: Labor Day holiday - JLab closed