Jefferson Lab Weekly Briefs
July 27, 2011

12 GeV Upgrade

Thirty-six of the 48 barrel calorimeter modules for Hall D have now arrived at JLab from the University of Regina, Saskatchewan, Canada, with four more expected by the end of July. The first full layer of the forward drift chamber has been assembled (of 24 total needed), and is now being tested. The custom preamplifier ASIC, used for the forward and central drift chambers, has been produced via the MOSIS service at the University of Southern California and has been sent for packaging. All straws needed for the central drift chamber have arrived at Carnegie Mellon University, with 22 of the 28 barrel layers of straws inserted and wire-stringing done for four layers. The main production of 2500 (out of 3000 total) bases has been ordered by Indiana University for the lead-glass forward calorimeter.

Physics

In Hall B, the cryostat that will hold solid targets of polarized deuterium-hydride (HD) at the center of CLAS next November achieved its temperature goal of 0.05 Kelvin on July 22. The HDice group bubbled dilute 3He through super-fluid 4He to reach the low temperature, making it the first dilution refrigerator built to DOE’s new ASME code requirements. Solid HDice targets are polarized at even lower temperatures in the Test Lab and trucked to the experimental hall. Once loaded into the new in-beam cryostat for the coming g14 run, the spin can remain aligned for years. Using solid HD as a target provides unprecedented purity and will open a new window to the spectrum of the nucleon.

Accelerator

The injector experiment (PEPPo) continues with equipment checks in the injector. The new 5 MeV vacuum chamber's alignment check and leak check were both satisfactory. West arc magnet cooling water hose tightness and leak checks are ongoing. East arc magnet installation, alignment and hookups continue to go very well. Significant progress is being made in zone 2L24; at mid-week, the radiofrequency system was on at 1 kilowatt, and by the end of the week, RF was on to all eight klystrons at ~10 kW. As the power is ramped up, control system checks look good. Installation and circuit checks in 2L25 are coming along nicely, with six of eight klystrons installed at midweek.

Free-Electron Laser

FEL staffers prepared the gun for high-voltage conditioning and verified that the cathode protection mechanism was working. The group also installed the krypton gas system for processing. At the end of the week, the team started conditioning the gun under vacuum, reaching 220 kilovolts and noting that with the beamline still baking, and the pressure higher in the gun, the onset of gas desorption came sooner.

Center for Theoretical and Computational Physics

The I = 2 π π s-wave scattering phase-shift is computed in a new paper below the inelastic threshold using lattice QCD. These results are combined with chiral perturbation theory to extract the scattering phase-shift (and threshold parameters) at the physical pion mass. The analysis finds results that are consistent with determinations from the Roy equations and with the existing experimental phase shift data.

Engineering

The installation team is continuing work on the beamline components in the east arc's south quadrant. The low-conductivity water hoses are also being installed at this time. The LCW tightness checks have been ongoing in the west arc's south quadrant. In Hall A, the FZ1 dipole for the G2P experiment was installed. Additionally, the FZ2 stand was installed and grouted. The vacuum group continues to perform hook-up and routine maintenance throughout the entire machine.

 

 

 

Environment, Safety, Health and Quality

Pedestrians Reminded to Use Sidewalks at JLab

The ESH&Q Division reminds everybody at JLab to use the sidewalks, crosswalks and marked foot paths when walking on JLab property. With the volume of traffic on our roads and in our parking lots and the variety of vehicles, it is important to separate pedestrians and vehicles. Walking through parking lots and on roads can expose pedestrians to unnecessary risk. Recently, new walking path signs were added between the VARC and CEBAF Center to help remind people to use the sidewalk running down the east side of the parking lot. In addition, a new crosswalk was painted to connect the ARC and Building 19 sidewalk with the sidewalk running between the VARC and CEBAF Center. If you become aware of an area where a crosswalk or marked foot path could improve pedestrian safety, contact Tina Menefee. Here are some additional safety tips for pedestrians and drivers onsite:

  • Use sidewalks, crosswalks and marked paths whenever possible;
  • When you have to walk on roads: Walk facing the oncoming traffic and stay on the shoulder of the road as much as is practical and safe;
  • Avoid walking behind parked cars or between cars in parking lots when possible; walk around the outer edge of the parking lot or walk across it at its narrowest point;
  • Don't walk through or around construction areas;
  • Don't walk around or between vehicles that are being loaded or unloaded;
  • When driving, heed all signs and painted markings, and always watch for pedestrians.

Announcements

Mont on the Six Month Shutdown
The latest Montage has been posted to the JLab website. Montage is an ongoing series of articles about issues affecting the lab written by JLab Director Hugh Montgomery. Click the link for Montage or access it via the JLab homepage.

Six Month Shutdown Safety Briefing
The video of the July 21 all-staff meeting to discuss the progress of the Six Month Shutdown project, including recent safety incidents, is now available on the web.

Stockroom Adds Tools to In-Stock Catalog
In an effort to provide JLab work crews with additional items that are vital to their work, the Technical Stockroom is adding a variety of hand tools to its stock items. Stockroom staff can make these tools readily available to its customers, sometimes within minutes. These items include some wrenches, tool bags, wire strippers, screwdrivers and slip joint pliers. For more information, contact Bill Brisiel at x7233, John Ferreira at x7225 or Lawrence Ferbee at x6297 or view the items online from the stockroom webpage.

Department of Energy Sponsors Food Drive Through Aug. 5
The DOE is participating in the "Feds Feed Families" drive this year. At JLab, the Thomas Jefferson Site Office (TJSO) has invited lab employees to participate in the food drive. Anyone wishing to participate may place non-perishable donations (non-glass items) in the marked barrels located in the CEBAF Center lobby through Aug. 5. For more information on the program, see the website or contact Steve Neilson at x7215.

JLab Community Invited to Summer Interns Poster Session
Thirty high school and college students participating in summer science internship programs at JLab will share their experiences and projects during a poster session scheduled for Friday, July 29, 11:45 a.m.-1:30 p.m. in the CEBAF Center lobby. The JLab community is invited.

Engineering Announces Special Cryo Seminars
Two cryogenics seminars, part of the Engineering Division's Professional Development Program, will address recent developments in cryogenics. The Aug. 4 seminar is titled: Cold End Process Options for Nominal 2 Kelvin Efficiency Improvements; and the Aug. 16 talk is titled: JLab's 12 GeV Compressor System and Development Work. Each event is scheduled for 1:30-3 p.m. in the CEBAF Center auditorium. For additional information, see the Cryogenics Seminars poster. General inquiries about these seminars or the Engineering Division's Professional Development Program may be directed to Gayle Coleman, x7712.

JLab Property Passes Now Available Online
JLab equipment and property - including laptops, computers or monitors - must sometimes be taken offsite for official business. Before JLab property may be taken offsite, the person taking the items must get a valid JLab Property Pass. Property pass applications may now be filled out online. Refer any questions or concerns to Lamont Williams, x6270; Carl Iannacone, x5430; Tony Lumanog, x7688; or TJ Sessoms, x7348.

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 to Dave Fazenbaker, who was the first person to correctly identify the July 20 location. Honorable mentions go to Jason Willoughby, Michael Spata, Whit Seay, David Abbott, Randy Michaud, Kelly Mahoney, Andy Kowalski, Eric Forman, Doug Higinbotham, Lori Zukerman and Harry Fanning. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.

JLab Calendar of Events

July 29: Summer Intern Programs Poster Session, CEBAF Center lobby
Aug. 4: Cryogenics Seminar
Aug. 16: Cryogenics Seminar
Aug. 22-26: PAC 38
Sept. 5: Labor Day holiday; JLab closed