Jefferson Lab Weekly Briefs August 31, 2011
Jefferson Lab Weekly Briefs
August 31, 2011
12 GeV Upgrade
Civil construction continues to make progress during the Six Month Shutdown. At the South Access building, the upgrades to the low-conductivity water systems are near completion. The pumps for the east arc are circulating water and the pumps for the South Linac are scheduled to be started this week. For the new tunnel penetrations at the beam switchyard, the holes have been augured to the tunnel roof and sleeved. The initial core into the tunnel roof and grouting is complete for one of the penetrations. After the grout is set and the sleeve is determined to be watertight, a second core will be done to penetrate completely through the tunnel roof, anticipated to be next week. At Hall D, the walls for the tunnel extension to the existing northeast tunnel stub are complete. The watertight partition inside the existing northeast tunnel stub will be completed this week. Upon completion of the watertight partition, the subcontractor will start saw-cutting the existing tunnel roof and east wall for connection of the new tunnel extension to Hall D.
In Hall A, the g2p installation is continuing. There was a problem with the target platform delivered from the vendor; some parts were made with a too-thin material. A new platform is being fabricated on a rush basis. Apart from that, the installation is on schedule.
Dance Your Ph.D. Contest Call for Entries
In the injector, the annihilation counter source measurement was completed for the Polarized Electrons for Polarizerd Positrons, and the 45 MeV spectrometer is back in place awaiting alignment and multiple hookups. In the arcs, the final four-meter dipole was installed. In the east arc, dipole hookups and magnet torque checkouts have been found to be okay. The South Linac tunnel is being locked up early in the mornings for 2L24 superconducting radiofrequency testing during the day and into the night. Equipment installation and testing continues in the other zones, 2L22-2L26. Installations that have been completed include 2L23 LCW hoses, field control chassis, AC Distribution, low-level RF PZT amp and the stepper motor control chassis. Hurricane preparations were completed by the end of the week, with a lot of equipment powered down and secured. Power was lost Saturday, and recovery of the cryogenics and systems began Sunday morning. Equipment and procedures put in place after Hurricane Isabel greatly reduced the impact of the outage.
It has been an exciting week dealing with natural disasters. The drive laser and Central Helium Liquefier continued running through the 5.8 earthquake; the beam was not running at the time, but FEL staffers expect that would also have been okay. The team spent the latter part of the week preparing for Hurricane Irene; all team members made it through okay, with no major damage. The FEL team continues to try to resolve a stubborn field emission site in the FEL gun.
Center for Theoretical and Computational Physics
A comprehensive analysis of target mass corrections (TMCs) to structure functions has been performed by a collaboration of theorists from JLab, Hampton University and students from the DOE Science Undergraduate Laboratory Internship and NSF Research Experiences for Undergraduates summer internship programs. Several different prescriptions for TMCs were considered, along with their impact on various observables, such as the neutron to proton structure function ratio and parity-violating electron scattering asymmetries for protons and deuterons, which are sensitive to γZ interference effects. Understanding these corrections, which play an increasingly important role at large quark momentum fractions x and low momentum transfers squared Q2, will be vital for the interpretation of future inclusive electron-scattering experiments at 12 GeV.
Environment, Safety, Health and Quality
Slips, Trips and Falls in the Office
Computing and Networking Infrastructure
Announcing the PC Purchase Program
CNI Maintenance Period Planned
Provide Feedback on JLab's Hurricane Irene Response
Onsite TIAA-CREF Counseling Offered
Tracking Thomas at JLab
Congratulations to Jason Willoughby, Kim Kindrew, Lori Zukerman, Narciso Gomez, DeAnn Maddox, Stephanie Vermeire and Kent Stephenson, who were the first to correctly identify the Aug. 24 location. Honorable mentions go to Dana Cochran, Michael Haddox-Schatz, Susan Brown, Tanya-Gaye N. Stewart, Michelle Shinn, Jodi Patient, Dick Owen, Samika Hawkins, Lamont Williams, Mike Koch, Ron Bartek, Casey Heck, Doug Higinbotham and Cindy Eller. 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