Jefferson Lab Weekly Briefs May 28, 2008
Jefferson Lab Weekly Briefs
May 28, 2008
12 GeV Upgrade
The solicitation (Request for Proposal) for the construction of the Hall D Complex was issued on May 23. The construction contractor will be selected through a two-phase, best-value determination process. In the first phase, interested Offerors are required to submit a Qualifications Proposal addressing their experiences with similar projects and their Environmental, Safety and Health (ES&H) program by June 14. The selection committee will evaluate these proposals and the Offerors’ past performance. In the second phase, Offerors will submit their technical proposals and their prices. This is currently scheduled to take place in August.
The 100 percent design package for the North and South Linac Power Upgrade was completed by the JLab Facilities Design Team and will be reviewed next month. This project provides a new 1.5 MVA electrical unit substation and switchboard at each Linac service building to provide power for the new RF zones.
In Hall A, production running for experiment E08-007, Measurement of the Proton Elastic Form Factor Ratio at low Q2, continues to progress smoothly. So far, five of the nine scheduled kinematics have been completed.
In Hall C, production data taking for the highest Q2 point of 8.8 (GeV/c)2 for the GEp/GMp measurement has been completed. Data are now being taken at 6.8 (GeV/c)2, the final kinematics setting for the experiment.
The Accelerator continued to deliver highly polarized beam to all three experimental halls throughout the period, with the scheduled accelerator down (SAD) now less than two weeks away. Weather continued to be a factor in beam delivery, as several more power glitches were experienced, making it the major contributer to lost beam time yet again.
Free-Electron Laser (FEL)
FEL staff is proceeding to complete planned diagnostics assembly for the gun test stand, as staff members finish installation of a bleed valve in the sulfur hexafluoride (SF6) tank. A new high-power coupler for the kicker cavity will permit longitudinal measurements of the beam. Substantial progress is being made on preparations for assembly of the Advanced Energy Systems Booster cryounit.
The first prototype of the M5 mirror, designed for collimation of the terahertz beam in the lab, was characterized by Peter Takacs at Brookhaven National Lab. The M5 prototype was machined in house using a new CNC milling system in the JLab machine shop. The surface was then polished to improve the finish. Measurements indicate a surface root-mean-square roughness of ~50 nm. This far exceeds the surface finish requirements for the long-wavelength THz light, and it appears that the JLab machine shop now has the capability to machine and polish THz mirrors of any shape and focal length. This capability will provide FEL staff great freedom when designing new THz optical systems.
Target mass corrections (TMC) to unpolarized deep inelastic scattering (DIS) structure functions have been computed (arXiv:0805.1496 [hep-ph]) in the context of perturbative QCD collinear factorization, which avoids ambiguities related to the moments inversion affecting the classic operator product expansion treatment of Georgi and Politzer and allows one to obtain TMC-corrected structure functions without unphysical contributions at xB > 1. When performing global QCD fits of parton distribution functions (PDF) in the context of collinear factorization, this procedure may be the most consistent way to treat TMC, with the advantage to be extendable to processes other than DIS. The impact of a final-state jet function on the extraction of PDFs at large xB is also evaluated.
The mechanical installation group is in the process of reassembling the first of 10 SF sextuple magnets in the FEL enclosure. A mockup was done previously in the south access building to ensure a smooth installation process. The ESSIC (Electrical Instrumentation and Controls) group has been making good progress in the testing and assembly of vacuum components for the FEL UV upgrade. Some of these components are the control modules, fast change modules and the beam position monitors for the ultraviolet line.
Environment, Safety, Health & Quality
Only sustained, hard freezes kill dormant ticks, so this year's mild winter is likely to spawn a bumper crop of ticks this spring and summer. The woods around JLab are notorious for their tick populations. Ticks are not merely an annoyance; some carry potentially serious diseases.
If your job requires you to go into underbrush or forested areas, take precautions. Wear light-colored garments, and seal them tightly at the cuffs and neck. Use tape-on cuffs if necessary. Avoid brushing against branches and leaves. Use insect repellents on exposed skin, and check yourself thoroughly as soon as you can afterwards (Ticks tend to crawl into well-concealed areas). The sooner they're removed, the less the possibility of disease transmission.
Always see a physician for possible diagnosis, testing and treatment, especially if tick parts remain after removal or you notice a rash or unusual discoloration at the bite site. JLab Occupational Health Services has information on tick-borne diseases, and there is a good fact sheet on the Centers for Disease Control website.
JLab's Safety Numbers
252 Days since Last Recordable Accident (JLab record: 319)
SAF600 ISMS Awareness Session
2008 Peninsula Pilots Opening Night Tickets Available
TIAA-CREF June Retirement Counseling Session
JLab Calendar of Events
May 25-31: Virginia Tax Holiday for Hurricane Supplies
JLab Education Calendar