Jefferson Lab Weekly Briefs May 20, 2009

Jefferson Lab Weekly Briefs

May 20, 2009

12 GeV Upgrade

Detailed physics simulations for the CLAS12 detector in Hall B suggest that a change in the diameter of the inner warm bore of the torus magnet will improve operation of CLAS12 wire chambers at full-design luminosities. The impact of this bore change on mechanical dimensions, integrated field values and stress analysis was studied and found to be small. A Change Request describing this design change was submitted to the 12 GeV Change Control Board and was approved.

Hall D recently held a three-day collaboration meeting at JLab, mainly dedicated to updates on various subsystems, while Hall B held a meeting with foreign collaborators on vertex tracking systems in the CLAS12 central detector.


In Hall A, production running for experiment E05-102, Measuring the Transverse Asymmetries in the 3He(e,e'd) Reaction, has been proceeding very smoothly.

Hall B is currently carrying out the second part of two highly rated experiments on generalized parton distributions and transverse-momentum dependent parton distributions. After an initial one-week delay due to an incident that damaged a vital component of the polarized target, the run has been going well, and some of the lost time has been made up by excellent performance of the accelerator and the polarized target. Target polarizations in the range of 75-85 percent have been achieved. The experiments also make use of the lead-tungstate crystal calorimeter to detect high-energy photons at very forward angles. So far, the calorimeter has been performing flawlessly.


The accelerator was running well, with some isolated incidents. Monday morning, May 11, there was a power loss in the east arc due to a local breaker trip. That evening, the east arc box supplies tripped off twice, most likely due to power surges. Several hours were spent for beam studies. On Saturday evening, a west arc vacuum valve closed due to a cracked air hose, and the faulty hose was replaced. Sunday morning, two vacuum valves in the South Linac closed due to deteriorated high-voltage cabling. The valves were opened and the faulty cable will be replaced during the summer down.

Free-Electron Laser (FEL)

Taking advantage of the FEL's continued down for the low-conductivity water line installation, the team has made good progress on the ultraviolet line. This week, staffers activated the beam viewers, which use the first control system  implemented with PC/104 and the required infrastructure. In addition to this, staffers also did work on the gun, drive laser, optical transport system and mechanical systems for the new gun and the UV beamline.

Theory Center

A new technique has been developed <arXiv:0905.2160 [hep-lat]> for constructing quark operators in lattice QCD, which allow efficient calculation of a broad range of hadron correlation functions. The method yields promising signals for meson, baryon and multi-meson systems on realistic lattice sizes with light dynamical quarks. The techniques outlined in this paper will be used in a range of spectroscopy determinations to support the JLab experimental physics program.

JLab's Safety Numbers

135 Days since Last Recordable Accident (JLab record: 331)
252 Days since Last Lost Workday Accident (JLab record: 676)

JLab Calendar of Events

May 20: JLab Annual Run-A-Round
May 25: Memorial Day holiday, lab closed
May 27: Safety Glasses Vendor onsite
May 28: Safety Shoe Vender onsite
June 1-19: HUGS 2009
June 2-4: 53nd Annual Materials Management Workshop
June 8-10: Users Group Workshop and Annual Meeting

Summer Education Calendar
June 1-19: HUGS 2009 - Hampton University Graduate Students
May 26-July 31: SULI - Science Undergraduate Laboratory Internship
May 26 - July 31: REU - Research Experience for Undergraduates
June 18 - July 31: HSSHP - High School Summer Honors Program
July 7 - 31: DOE ACTS - Academies Creating Teacher Scientists




Environment, Safety, Health & Quality

According to 2007 U.S. Bureau of Labor Statistics data, falls down stairs or steps, falls from floor, dock or ground level and falls on the same level accounted for 19 percent of falls that resulted in fatalities. BLS data from 2006 showed that floors, walkways and ground surfaces were the source of injury and illness for 18 percent of all days-away-from-work cases. Also in 2006, slip, trip and loss-of-balance injuries without falls led to 35,440 non-fatal injuries.

Although worker injuries and fatalities due to slips, trips and falls have increased over the last five years, the good news is that they are highly preventable. Contributing factors, such as flooring type and condition, workplace environment, footwear and human behavior, can be readily addressed with the right tools in place. In fact, studies have shown that workplace slip, trip and fall prevention programs can significantly improve workplace injury rates over time. These programs identify hazards long before they have the potential to turn into serious incidents, and the programs help workers better recognize and report hazardous conditions in the workplace.

JLab's last reported slip, trip and fall incident occurred last August. Various preventive measures have been implemented to prevent further occurrences, such as the evaluation of all site entrances and exits for non-skid application, use of the safety paths between the ARC and CEBAF Center, and heightened communications regarding slip, trip and fall safety. Given the wet conditions of the season, all lab personnel should remain aware of these hazards.

Computing and Networking Infrastructure

Computer User Audit Ongoing
The JLab semi-annual user audit started on May 4. If you are a supervisor or sponsor, you should have received an e-mail asking you to go to Insight and click on the "User Audit" link under "Personal Information." The audit must be completed by May 26.

IT Helpdesk Summer Hours
Starting on June 1, the IT Division Helpdesk will be open from 8 a.m. until 4:30 p.m. Monday through Friday, with a 30-minute break during lunch from 12-12:30 p.m. It will revert back to morning-only hours at the end of the summer.

Security Awareness Training
As part of the JLab Computer User Audit, the lab must verify that all staff and users have taken the latest Security Awareness Training (GEN034). If you have not yet taken this training, go to the Web-Based Training webpage and select the appropriate Security Awareness training.


Check Out the Latest Montage
Mont's latest column is now available online. Click the link to read about the director's take on his first spring at Jefferson Lab.

Last Chance to Enter the APS Toy Box Physics Contest
Like tossing yo-yos? Ever wanted to unravel the mystery of the drinking bird? Then the Toy Box Physics video contest is for you. Take any toy you want and use it to somehow express a physics concept. Bounce, spin, jump and splash your way into physics history. The winner will receive a trophy lovingly made by American Physical Society staff from some of our favorite physics toys as well as $1,000 cash. All entries must be received by May 26 at midnight.

Virginia’s Hurricane Preparedness Sales Tax Holiday
All Virginians should take steps to prepare their families for any emergency by getting an emergency supply kit, making an emergency plan and staying informed about the hazards that could affect their area. Detailed instructions for getting ready for emergencies are online. The General Assembly established an annual sales tax holiday to ease the cost of creating an emergency supply kit. From May 25-31, the purchase of certain items is exempt from the Commonwealth’s sales and use taxes. Customers may use manufacturer’s coupons to lower the price of an item so that it will qualify for the $60 or $1,000 price cap. Items include bottled water, flashlights, battery-powered radios, batteries and first aid kits. The entire list of tax-free items is available online.