Jefferson Lab Weekly Briefs
March 18, 2009
12 GeV Upgrade
Significant progress continues on accelerator construction contracts. The request for Best-and-Final Offers for the fabrication of the superconducting radiofrequency cavities is ready to be issued. The BAFO for the 4m dipole fabrication has been issued. BAFO submittals for the klystron contract have been received. Responses to the Request-for-Information for the large magnet power supplies have been received and discussions have started with some potential vendors. A modified procedure for testing the higher-order-mode (HOM) damping of the srf cavities prior to installation in the cryomodules is being developed; first tests with the improved procedure are expected this week.
In Hall A, experiment E06-014, Precision Measurements of the Neutron d2: Towards the Electric and Magnetic Color Polarizabilities, ended its run early Monday morning after accumulating over 80 percent of the scheduled production data.
After many challenges, the Spin Asymmetries of the Nucleon Experiment was completed in Hall C. The experiment took data with 4.7 and 5.9 GeV beams with the polarized target oriented both parallel and perpendicular to the beam. The experiment obtained over 70 percent of the proposed statistics for the more important perpendicular running and about 40 percent of the proposed statistics for the parallel orientation. These amounts of data are about what was expected when the run plan was reworked after the polarized target magnet was repaired in December. The four SANE spokesmen are Oscar Rondon Aramayo (University of Virginia), Zein-Eddine Meziani (Temple University), Mark Jones (Jefferson Lab) and Seonho Choi (Seoul National University).
During the first three days of last week, the accelerator was down due to vacuum issues of cryomodule 1L04. Thursday, the vacuum was better and beamline valves were opened. In order to have a stable machine, cryomodules 1L03, 1L04 and 1L05 were left off and the accelerator was reconfigured from 5.9 GeV to 4.7 GeV. By Thursday evening, continuous wave beam delivery was resumed, and the accelerator ran well until Monday morning, when the scheduled down started.
Free-Electron Laser (FEL)
FEL staffers had a great week of running beam with initial tests on short Rayleigh-range performance. Later in the week, staff conducted a set of tests on a new edge outcoupler and tested off-axis injection to the machine. The outcoupler tests were particularly interesting, providing staff the capability for modestly high-power broadband radiation out to the limits of transmission of the substrate, 3.86 microns, while showing small signal gains substantially in excess of 60 percent.
A comprehensive study of two-boson exchange (TBE) corrections in parity-violating electron-proton elastic scattering has just been completed (arXiv:0903.2759), in which the intermediate states in loop diagrams are described by nucleons and Δ baryons. The Δ contribution is found to be much smaller than the nucleon one at backward angles, but it becomes dominant in the forward scattering limit. Corrections are computed at kinematics relevant for recent and planned parity-violating experiments, such as the HAPPEx, G0 and Q-weak experiments at JLab.
JLab's Safety Numbers
72 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
March 25-27: International Workshop on Positrons at Jefferson Lab
Environment, Safety, Health & Quality
Causal Analysis facilitations were recently completed for the Fall Protection Assessment conducted in November. Jefferson Lab conducts facilitations to identify underlying problems with programs, either systemic or functional. The causal analysis results are then used to identify corrective actions, with the intent of preventing recurrence. ESH&Q staff also conduct these investigations for any DOE P-2 finding, which is defined as representing nonconformances, deviations and/or deficiencies in the implementation of requirements, procedures, standards and/or regulatory requirements.
For the Fall Protection Assessment, a cross-functional team evaluated eight separate issues for all potential causes. Each case was then used to develop a corrective action plan.
On a separate note, a Safety Award was recently presented to Hui Tian for her awareness and prompt reporting of a spill in the Test Lab R&D Chemistry Room. While working in the room, she discovered that several ounces of a brown liquid had run down the outside face of the left hood cabinet at waist level and lower. She promptly contacted the area Safety Warden. It was determined that the spilled liquid was an acid and cleanup was completed without incident. Hui’s actions to identify and notify the appropriate personnel prevented users and staff members from contamination or injury by the spill. This event will be posted as a Lessons Learned in the coming days.
Computing and Networking Infrastructure (CNI)
E-mail Outage and Reconfiguration Begins Friday, March 20 at 10 p.m.
The location of e-mail folders is being changed. Currently, JLab account holders have e-mail folders that are stored in their home directories (/home/user on Unix or J: drive on Windows). The reconfiguration will move these folders out of account holders' home directories and place them on a standalone, isolated file system. Account holders will not have direct access to this new file system. All access to these folders will require an IMAP mail client (i.e. Thunderbird, Pine configured as an IMAP client, etc). Further information about this reconfiguration is available on the CNI group web page.
Pager System Upgrade
Last Chance to Enter JLab's T-Shirt Design Contest!
Softball Team First Practice is Friday, March 20 at 6:30 p.m.
Quark Cafe Celebrates National Nutrition Month
Quark Cafe's Hot & Toasty Sandwich Club
Interested in golf?