Jefferson Lab Weekly Briefs August 11, 2010
Jefferson Lab Weekly Briefs
August 11, 2010
12 GeV Upgrade
The intermediate manufacturing readiness review for the torus magnet for the Hall B CLAS12 spectrometer was held in July at the vendor, Wang NMR. Short sample tests of the superconducting cable for the solenoid magnet were completed successfully at the University of Twente, the Netherlands, and the cable was shipped to Wang NMR. The production of the extruded scintillator for the Pre-Shower Calorimeter (PCAL) for CLAS12 concluded at Fermilab, and orders were placed for the PCAL wave-shifting fibers by The College of William & Mary and JLab. Stringing of guard wires and field-shaping wires was completed for the first sector of the CLAS12 Region 2 Drift Chamber. This first sector is being built as a joint effort among Old Dominion University, Idaho State University and JLab. A contract has been readied for ODU to string the remaining five Region 2 sectors. Molds were machined at JLab for the mirror production for the CLAS12 High Threshold Cerenkov Counter (HTCC). Seventeen (of 48) of the HTCC five-inch diameter quartz-face photomultiplier tubes have arrived and are being tested. For a Forward Time-of-Flight wall, a series of tests of candidate photomultiplier tubes and scintillator material were concluded with the participation of the University of South Carolina.
In Hall C, attempts to cool the Q-weak target did not succeed due to a leak in the target cell. Q-weak detector checkout and commissioning has continued with solid targets. In addition to tracking detector checkout with low-current beam, studies of the detector response to helicity-correlated beam properties have started. The Moller polarimeter, which was reassembled at a new position during the beamline upgrade, has been recomissioned. Commissioning of the new Compton polarimeter has started with the successful tuning of beam through the chicane with the laser on in the interaction region.
Early Career Research Program Pre-Applications Due Friday
The accelerator was running over the weekend. Instability in the gang phase of the north linac radiofrequency system cleared up on its own. On Thursday, gun2 was hi-potted to 130 kiloVolts to eliminate field emission. On Sunday, the Central Helium Liquefier tripped off and was recovered a few hours later. After the CHL was recovered, vacuum valve VBV2L17A would not open. It was found that the insulating vacuum pump of zone 2L17 tripped, and the solenoid of VBV2L17A was leaking air. After the pump was turned on and the solenoid replaced, VBV2L17A was opened. Beam delivery resumed on Monday day shift.
The final major component needed before commissioning the Ultraviolet FEL, the narrow-gap wiggler chamber, was completed and was ready for final leak-checking and cleaning. With the temporary chamber removed, the team had the opportunity to check out the wiggler gap mechanism, which is now ready for operations.
JLab's Safety Numbers
26 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Computing and Networking Infrastructure
Shutdown of wireless network 'jlab_secure' on Aug. 24
Power Outage this Weekend
Scientific Computing Outage
Redhat Enterprise Linux Version 3 Support Ending
Pre-SAD Safety Meeting
Health Care Reform and JLab Benefits
Return to Vendor Form Online
JLab Strategic Plan Available Online
Can You Find Technical Information Faster with Knovel?
United Way School Tools Drive