Jefferson Lab Weekly Briefs December 10, 2008
Jefferson Lab Weekly Briefs
December 10, 2008
12 GeV Upgrade
Significant progress has been made on finalizing the engineering and design of the Hall D beamline and associated physics equipment, as endorsed by a recent review. The Hall D electron beamline design has been completed and simulations prove it to be robust, with flexible tuning and well-defined instrumentation and tuning knobs to verify beam performance. A well-founded shift was made from a two-magnet system to a single magnet for the photon-tagging spectrometer, with many advantages. Additional diagnostics of the photon beamline, including a pair spectrometer, have been developed in order to obtain a thorough knowledge of the photon beam spectrum that is essential to the GlueX science program.
In Hall A, Experiments E06-010, Measurement of Single Target-Spin Asymmetry in Semi-Inclusive Pion-Electroproduction on a Transversely Polarized 3He Target, and E07-013, Target Normal Single-Spin Asymmetry in Inclusive DIS n(e,e') with a polarized 3He Target, are now in stable production mode. The installation of three narrow-band lasers has further improved the polarized helium-3 in-beam target polarization from around 60% to around 65%.
JSA Accepting Applications for Graduate Fellowships at JLab
PAC 34 Call for Proposals Due Dec. 15
Overall, the accelerator has been running well. The maintenance on magnets and radiofrequency (RF) systems lowered the beam trip rate. A failed sump pump caused some ground water to leak into the West Arc tunnel. The problem was found and addressed during a scheduled maintenance. Problems were encountered restoring beam after Tuesday'’s maintenance day, due to a significant change in beam pathlength. Beam delivery resumed after the pathlength was properly adjusted.
Free-Electron Laser (FEL)
FEL staff completed gun processing up to the running voltage with a good quantum efficiency and are initiating beam running. The cathode is not field emitting, but there does seem to be a residual field emitter on the ball, which may affect running lifetime between cesiations. The optical system is now installed and aligned. The AES Booster was moved to the Test Cave for end cans and qualification.
Using recent data on dihadron production in deep-inelastic scattering and a recent parametrization of the transversity distribution, the magnitude of dihadron fragmentation functions was estimated in a recent paper (arXiv:0812.0611 [hep-ph]). Applying QCD evolution equations, an asymmetry involving the dihadron fragmentation functions was predicted in electron-positron annihilation at much higher energies. Once this asymmetry is measured at BELLE, the procedure can be inverted and the transversity extracted more cleanly than in the past using single-hadron fragmentation functions.
JLab's Safety Numbers
91 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Dec. 8-12: Muon Collider Design Workshop
Environment, Safety, Health & Quality
As winter settles in to Hampton Roads, ESH&Q wants to ensure that users and employees know how to stay safe not only at work, but on their way to and from the lab and in their free time. The following safety tips can help:
Be prepared - Keep extra blankets, sand, a scraper and a small shovel in your trunk in case you become stranded. Keep a charged cell phone available to call for help. Stay current on local forecasts and weather reports. Clear your windows and lights of snow and ice before driving. Allow your car to idle about 20-30 seconds before pulling out gently; excessive idling only burns extra gas. Drive gently until the car's temperate gauge begins to indicate the car is warming up. Click for more winter car care tips.
Drive carefully - Use caution on snow-covered roads and when maneuvering beside large vehicles whose tires can spray snow into your windshield. Allow extra distance for your vehicle to stop. Watch out for “black ice” conditions where asphalt appears wet or normal but is actually covered in a thin layer of ice. Do not follow closely behind snow plows.
Walk defensively - Wear shoes that provide traction. Wear low heels when outside. Stay in areas cleared of snow and salted, while still maintaining an awareness of pavement conditions in case of surprises.
Computing and Networking Infrastructure (CNI)
Discounted Microsoft® Products for Personal Use Available
Discounted Microsoft® Products Available for Work at Home
End-of-Year Radiation Badge Change Out
Holiday Pie Orders Taken Through Dec. 19
Holiday Shutdown – Cafeteria Meal Notice
Survey to Assess Employee Concerns Programs
Children's Holiday Party
Toys for Tots Donation Drive
Calling All Amateur Interior Designers: Ready, Set, Decorate!
Children's Holiday Party Volunteers Needed