Jefferson Lab Weekly Briefs
November 4, 2009
12 GeV Upgrade
Procurement activities continue as the focus of the 12 GeV accelerator team, with more than $22 million of awarded contracts and an additional $7 million in the procurement process. During the past month, meetings were held with the vendors of the 4.5 K coldbox for the new Central Helium Liquefier and the septa magnets for the beam transport system. Audits were carried out of the quality assurance/quality control programs of some potential vendors; reports are pending. Detailed planning is underway for installation work during the January and July accelerator downs in 2010. The final pre-construction design and safety review for the magnet power subsystem was held.
In Hall A, production data taking for experiment E05-109, HAPPEx-III, a measurement of the nucleon strange form factors at high Q2, was interrupted on Tuesday, Oct. 20, by a sitewide power outage. Recovery from the damage this caused was so extensive that it was decided to end the experiment on Oct. 28, one day earlier than scheduled, after all essential calibration data had been taken. In the end, HAPPEx-III succeeded in obtaining nearly 70 percent of the production data that had been planned.
In Hall C, the hypernuclear experiment E05-115 in Hall C has been completed, coming close to obtaining all the proposed data. Production data was taken with lithium-7, beryllium-9, boron-10 and chromium-52 targets. In addition, calibration data was taken with water, polyethylene and carbon targets. The hall is now removing the High Resolution Kaon Spectrometer experiment and starting the installation of the Q-weak parity experiment, scheduled to start commissioning in May.
The accelerator site lost power again around 12:30 a.m. Tuesday, Oct. 27. The power outage was most likely due to some faulty parts in the power line feeding into the lab. Dominion replaced the faulty parts. Beam delivery was resumed at the end of Wednesday’s owl shift. On Wednesday afternoon, the injector and Hall B were taken down to controlled access briefly for a tour. On Sunday, Hall B was changed from 1-pass to 5- pass beam. The accelerator energy change to 6.068 GeV began Monday.
This week saw the achievement of a major milestone in the progress of the JLab FEL: first beam through the UV beamline after three years of assembly, installation and checkout. It took less than two hours to successfully recover beam through that line. This sets the stage for lasing next spring after installation of the optical systems and wiggler chamber and diagnostics. The team also put light on a grating for the ring resonator effort, took terahertz data, measured radiation backgrounds for a user and took an extensive set of data on injector halo production and average current limits in the present setup.
Using a new technique recently developed at JLab, a collaboration between Theory Center staff and experimentalists has extracted the neutron F2n structure function from inclusive proton and deuteron data in the large-x region <arXiv:0910.4920 [hep-ph]>. The data have been used to test the validity of quark-hadron duality in the neutron and establish for the first time the accuracy of duality in the low-lying neutron resonance regions over a range of Q2. The findings open the possibility of using resonance region data to constrain leading-twist parton distributions at large x.
Computing and Networking Infrastructure
JLab Wireless Access Changes
Linux Patches To Be Sent Out Tuesday
JLab Veterans Day Salute on Nov. 11
JLab's Safety Numbers
112 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Nov. 12: Safety Shoe Vendor onsite