Jefferson Lab Weekly Briefs

November 14, 2007

Physics

In Hall A, the Coulomb Sum Rule experiment, E05-110, has been taking production data, but was interrupted this week for two days to warm up the heat exchanger in the warm helium return to the Central Helium Liquefier that had completely iced up. The production run is characterized by a multitude of short runs at different spectrometer momentum and angle settings and beam energies for a variety of targets.

 

The frozen spin target, FROST, has been installed in CLAS. The target is polarized at about 90 percent and is operating in the dilution mode and frozen spin mode. The polarization decay time has been estimated at about 3,500 hours at 35 milliKelvin (mK) temperature. The target has been ready for data taking since Monday night and is awaiting suitable beam for production data taking for experiment g9a, a search for new excited baryon states using polarized photons and polarized protons.

 

In Hall C, production data taking for GEp-III and GEp-2γ is proceeding with a measurement at Q2 of 5.2 (GeV/c)2 in progress.

Accelerator

This was a very good period for the accelerator, with more than 285 hours of beam delivery distributed among the three experimental halls. Procedures accomplished included an energy change. One short-lived problem  was a failure of a fast valve controller card. It was replaced in the end of the North Linac. A longer-duration problem occurred when an End Station Refrigerator turbine bearing failed, bringing beam delivery to a halt while repairs are underway.

Free-Electron Laser (FEL)

President Bush signed a defense spending bill Tuesday that includes $2 million for the FEL. Safety approvals have been obtained for the 16-Tesla solenoid magnet test next week in the Terahertz lab. The radiofrequency systems were acid flushed. The Gun Test Stand gun tanks are now bolted together and ready to be pressure tested, and the safety enclosure for the GTS drive laser has been received. Preparations of the refurbished FEL gun continued, and the injector beamline is being prepared for a bake. A vexing problem was identified and fixed on the M55 accelerator diagnostic system. Lab 5 is now certified for local user operations.

Theory Center

Parity-violating electron-proton scattering is a technique that has been used at JLab to extract the strange form factors of the proton. To ensure that reliable information is obtained from the experiments, radiative corrections from two-photon exchange and photon-Z boson interference have been computed in arXiv:0711.0143 [nucl-th], which hitherto had not been accounted for in data analyses. Effects of order 2-3% were found at Q2< 0.1 GeV2, which are largest at backward angles, and have a strong Q2 dependence at low Q2.

Announcements

JLab Children's Holiday Party
The JLab Children's Holiday Party is set for Saturday, Dec. 8, from 10 a.m. to 1 p.m. in the CEBAF Center lobby. All children of Lab employees, contractors and users are invited. The JAG is planning crafts, snacks and a visit from Santa Claus. Each family is asked to bring a new, unwrapped toy donation for Toys for Tots. All children must be accompanied by an adult.

 

Quark Cafe Offers Thanksgiving Feast
Quark Cafe staff will host a Thanksgiving Buffet from 11:30 a.m. to 1:30 p.m., Thursday, Nov. 15. Food items may be purchased a la carte; or for $7.99, patrons get the buffet spread, which includes one plate, 24 oz. fountain drink and a dessert. The buffet will feature buttery sage and thyme-roasted turkey with home-style gravy, roasted duck with wild mushroom demi-glaze, spiral-cut ham, fresh herb stuffing, maple-glazed sweet potatoes, corn pudding, roasted acorn squash, rosemary-caramelized onion mashed potatoes, fresh cranberry-orange relish, herb cheddar drop biscuits and a selection of scrumptious desserts.

Holiday Desserts to Tempt Your Taste Buds
The Quark Cafe is taking Thanksgiving dessert orders through 2 p.m. Friday, Nov. 16. Desserts must be picked up on Tuesday or Wednesday, Nov. 20 or 21 (no later than 2 p.m.). Order forms are available in the cafeteria.
 

JLab's Safety Numbers
56 Days since Last Recordable Accident (JLab Record: 319)
375 Days since Last Lost Workday Accident (JLab record: 455)

JLab Calendar of Events

Nov. 22-23: Thanksgiving holidays
Dec. 4: Science Series Lecture: The Laser at 50
Dec. 8: Children's Holiday Party
Dec. 24-Jan. 1: Holidays/Shutdown Days

 

Environment, Safety, Health & Quality

It may not feel like it this week, but cold winter weather is just around the corner. Take some time this week to prevent damage to your home from your water pipes freezing and bursting. The Newport News Waterworks recommends the simple tips below to prevent major problems:

  • Seal air leaks or cracks in the crawl space;
  • Air vents should be closed or covered from the inside. Remember that wind blowing through openings or cracks can cause freezing more quickly than cold temperature alone;
  • Keep doors and windows water pipes closed during very cold weather;
  • Water pipes in unheated areas should be insulated;
  • Locate your water shutoff valve;
  • Drain outdoor faucets and irrigation lines.

SLAC Pipe Explosion Lesson Learned
A mid-September Stanford Linear Accelerator Center (SLAC) "near miss" event resulted from a pipe explosion. Fortunately, no one was seriously injured by the explosion that resulted from the ignition of accumulated PVC pipe cement vapors. The ignition source was a "hot tap" (an open flame process penetrating the pipe) during a pressure gauge installation in an adjoining steel pipe section. A SLAC investigation committee determined that the root cause of the accident was poor planning at several critical junctures. A part of the job, the installation of a pressure gauge on the steel pipe, was overlooked, and a last-minute fix went awry. If the work on the pipes had been well planned from beginning through completion, the event would almost certainly have been prevented. Planning and thought are needed prior to all work, not just this specific case. For JLab-specific information on hazard recognition, evaluation, and control, see the Lab ES & H Manual Chapter 3210 Hazard Identification and Control.

Computing and Networking Infrastructure

Dial-in Server Outage Planned
The Computer Center will be taking the system responsible for dial-in access (including the 1-800 number) offline for the morning of Thursday, Nov. 15. Dial-in access will be offline from 8:30 a.m.-noon for extensive troubleshooting.

Scientific Computing Maintenance Planned
The experimental physics off line scientific computing environment will be down for maintenance beginning Friday, Nov. 23 and continuing into Saturday as needed. Jobs will stop being dispatched to the batch farm at 5 p.m. on Tuesday, Nov. 20.

'Tis the season for E-Card Scams
Cybersecurity staff report that several JLab computer users have already fallen victim to fake e-cards containing computer viruses. Legitimate e-card notifications will always include the actual name or personal e-mail address of the sender. Visit the Greeting Card Association website for tips on how to identify legitimate and safely retrieve e-cards.

Microsoft Office 2007 and Windows Vista
The JLab IT Division will offer classes on Nov. 28 on two new software packages: one on the major differences between Microsoft Office 2003 and Microsoft Office 2007 and another on the major differences between Windows XP and Windows Vista. The Microsoft Office 2007 suite will be available for download and installation by JLab CUE Windows systems in mid-November. Anyone who uses this software frequently is encouraged to attend a training session, since the new version is dramatically different than older versions. See the full announcement for details.

Redhat Enterprise Linux 5 Now Available
On Wednesday, Nov. 14, The CNI group will be making Redhat Linux 5 available for installation. If you would like to install this version of Linux, please stop by the Help Desk (F200) and ask for an installation CD and instructions. There is currently no Geant 4 support for this version, but the Computer Center is working to make this available in the future.

Windows Vista Deployment Information
All new Windows-based system purchases should specify Windows Vista. Systems currently running Windows XP Professional should continue to do so until the hardware is replaced. Users who are interested in upgrading existing systems to Vista should examine Microsoft's hardware requirements carefully before proceeding. Systems currently running Windows 2000 Pro should be scheduled for upgrade to Windows XP, or replaced with new systems running Vista. For more information, see the Computer Center's Windows page.

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