Jefferson Lab Weekly Briefs November 19, 2008
Jefferson Lab Weekly Briefs
November 19, 2008
12 GeV Upgrade
JLab jointly sponsored an international workshop on Physics and Methods in Meson Spectroscopy in Munich Oct. 22 - 24 with more than 80 participants. The workshop encompassed meson spectroscopy with beams of protons and mesons (CERN-COMPASS), polarized photons (JLab-Hall D/GlueX) and antiprotons (GSI/FAIR-PANDA). Part of the workshop program dealt with the new analysis methods presently being developed to make optimal use of these high-statistics data sets and to improve the reliability of traditional partial wave analysis. The workshop was a great success, bringing experts from all over the world together to discuss this physics and the associated analysis methods. More information can be found online.
In Hall C, the Spin Assymetries of the Nucleon Experiment (SANE) is down because of problems with the superconducting magnet in the polarized target. After a five-day warmup, the magnet was transported to the EEL and the top "donut" opened. Unfortunately, no obvious fix was found. Oxford, the company that built the magnet, quoted six weeks to assess the magnet. With the time constraints in the beam schedule, sending the magnet to Oxford would be a delay that wouldn't allow the experiment enough time to run. So Hall C staff is going to continue studying the magnet at JLab to see if the problem can be isolated.
The accelerator provided 184 hours of beam to the two experimental halls during this period. The accelerator’s beam availability was reduced by two significant equipment events related to the Central Helium Liquefier. A Howden Compressor Oil Pump bearing failed, which required taking the CHL offline to replace the bearing. Unfortunately, soon after this problem was fixed, the CHL’s Turbine No.T3 had to be replaced. This repair effort was further delayed by the discovery of a faulty turbine seal on the replacement turbine. Once all repairs were successfully and safely made, the accelerator resumed beam delivery.
Free-Electron Laser (FEL)
FEL staff replaced the gun cathode and completed a short bake over the weekend. The gun had provided good current, but lifetime on the cathode was limited by field emission points from the cathode due to earlier damage. While working on that, staffers also made significant progress on stabilizing phase noise on the Advanced Drive Laser.
JLab has already played a major role in the exploration of strange quarks in the nucleon, providing a large part of the world's data on parity-violating electron scattering. For lattice QCD, the measurement of strange quark contributions involves so-called disconnected diagrams, which have proven extremely hard to measure. Indeed, the best determinations of the strange electric and magnetic form factors have come through indirect means. In recent work (arXiv:0811.1779 [hep-ph]), led by colleagues at the University of Kentucky, state-of-the-art methods were used to establish that the strange and anti-strange quarks in the nucleon carry about 2.7 percent of the momentum of the nucleon, with an error which puts this result almost 5 standard deviations from zero.
JLab's Safety Numbers
70 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Nov. 21-22: Lattice QCD and Experiment: Revealing the Structure of Hadrons
Environment, Safety, Health & Quality
Update (11/21/08): This ES&H Manual Chapter 6122 update is not complete. The chapter is currently being updated, and and an update will be available soon.
As part of Continuous Improvement efforts, ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program has been revised to incorporate updates that respond to the initial implementation of the program. The revision was made with the feedback of line users, addressing items such as repairs, required analysis, category clarification and additional examination requirements of Class B joints. The revisions have been approved and are posted to the website for site use. All ES&H Manual Chapter and Appendix updates will be announced in the Weekly Briefs as they occur and will be listed on the Insight page under JLab Safety Snapshot. Review these sources periodically for up-to-date information.
Computing and Networking Infrastructure
JLab Under Cyber Attack
Red Team activities can include attempts to hack into lab computer systems from both offsite and onsite. Recent Red Team attempts to get a toehold in a lab's network have been made through phishing and social engineering. Some successful examples include the sending of official-looking CDs in the mail or leaving a memory stick in a public place that installs Trojans when inserted into a computer, sending official-looking e-mails with embedded web links to malicious websites, and placing phone calls to users claiming they represent the Helpdesk.
Here are a few quick tips on practicing good cyber security:
These links provide useful information about thwarting cyber security attacks:
Holiday Desserts to Tempt Your Taste Buds
Mobile Mammography Unit Onsite Dec. 8
Quark Cafe Invites Your Input Through Online Survey