Jefferson Lab Weekly Briefs
January 30, 2014
12 GeV Upgrade
The concrete shield house for the Super High Momentum Spectrometer has been constructed on the new support carriage in Hall C. Next will be installation of specialized boron carbide and lead shielding panels. Work continues to upgrade the cryogenics infrastructure for Hall C to accommodate the new spectrometer. Construction of the first two of five spectrometer magnets is well advanced. Welding of the helium vessel is underway at Michigan State University for the HB dipole magnet, while parts for the nitrogen shield, vacuum vessel and support links are ready. The yoke quadrants and four coil assemblies have all been assembled for the Q1 magnet at Scientific Magnetics in the U.K. Welding of this assembly is underway and will be followed by addition of the helium vessel, thermal shield, and outer vacuum cryostat, all of which are ready to be attached. The prototype coil winding was completed for the dipole magnet at Sigmaphi in France and was then epoxied using vacuum pressure impregnation (VPI). Two winding stations are set up at the vendor in anticipation of the start of production coil winding in late February. Very similar tooling and techniques will be used afterward to fabricate the Q2 and Q3 magnets, starting in Spring 2014.
In-tunnel testing of C100-10, the final cryomodule for the 12 GeV Upgrade Project, has been completed. The total voltage for that cryomodule was found to be 110 Megavolts. Installation of all beamline components for the main racetrack has been completed, as well as alignment and vacuum leak checks. The rework of the YB’s for the beamline to Hall D has been completed. Vacuum hookups in the transport recombiner and the beam switchyard are complete up to the Personnel Safety System (PSS) stoppers, and the leak check of the Hall A beamline is well underway. A ground current issue for the arc 1 and arc 2 box supplies was discovered and is now resolved. The control problem with the arc 2 box supply has been resolved with the help of an engineer from the vendor, who also installed the corrected components for the IGBT’s in the arc 4 box supply. The arc 5 and arc 6 box supplies have been operated at full output current. Deliveries of 20 Amp trim supplies resumed; 65 new units and 20 repaired units were received in December and January; an additional 20 are in transit from the vendor. The order was placed for the electronics for the stripline beam position monitors (BPMs) on the beamline to Hall D. Installation of the PSS stoppers for that beamline is underway, as is PSS installation in the Hall D tagger vault and Hall D proper. Work on the beam dump and water skids for the Hall D tagger has resumed.
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Jefferson Lab Published Articles, Jan 13 - 25
Remember to submit your papers for approval to the Jefferson Lab Publications database.
Center for Theoretical and Computational Physics
A new paper reports an ab initio calculation of the neutral weak current response of 12C, based on a dynamical framework in which nucleons interact among themselves with two- and three-body forces and with external weak probes via one- and two-body currents. The two-body current contributions lead to a significant enhancement of the single-nucleon response, even at quasielastic kinematics, and this enhancement is driven by strongly correlated neutron-proton pairs in nuclei. The results can be used as constraints for more phenomenological approaches to the nuclear response, and to guide improvements to these models and analyses of quasielastic scattering in neutrino experiments.
The Electrical Engineering groups in the Engineering Division continue to split their efforts between 12 GeV equipment construction, installation and commissioning, along with restoration of accelerator beam operations. Vendor engineering support in mid-January allowed the DC Power group to complete full commissioning on magnet power supplies for arcs 1 and 2, while also troubleshooting testing problems with several other power supplies. Simultaneously, trim magnet power supplies and magnets shunts are being brought online. The Radiofrequency group has been fully engaged in completing the restoration of all RF systems in both linacs, with special attention given to the new 12 GeV RF zones. Assembly and testing of the rebuilt RF system for the injector cryomodule, 0L04, has been in progress. Full commissioning of this RF zone will be soon. The Instrumentation and Controls group is working on completing installation and commissioning of harps viewers and BPMs so that beam transport can be monitored and controlled by operations. Several groups (I&C, Safety System and Support Services) have been working to complete installation so that the "Accelerator Complete" milestone can be claimed this month. This work involves installation of the hardware in the Hall D transport line up to the beam stopper at the foot of the ramp into the tagger area. All groups have split time between completing their 12 GeV work and monitoring, maintaining, and repairing equipment so that beam could be successfully transported through both linacs to the start of the second accelerator arc.
Environment, Safety, Health and Quality
Danger for Road/Utility Workers in the Twilight/Dark
Road and utility workers continue to make headway on various projects either near Jefferson Lab or on the roadways to and from work. Their jobs entail long days spent near fast-moving vehicles, without much room to spare. The work areas are generally well marked, but workers do move around and often have to step out of the way and may forget that they are stepping into moving traffic.
According to the Bureau of Labor Statistics, more than 100 road workers are killed on the job each year. To reduce this statistic, drivers must to be more alert and drive with extra caution around construction zones, especially as those zones approach Jefferson Lab entrances. As the hours of darkness overlap business hours here at Jefferson Lab, you will need to be extra cautious during these times. Give the work zone as much room as possible when passing. Keep an eye out for workers who may not see your vehicle and step up into the edge of the road, thinking they have more room than they do. Pay attention to work zone markings and signs, and obey all directions, barriers and flaggers.
Travel Requirements Briefing for Travelers
JList Upgrade Set for Feb. 5
JAG Dog Club Starts New Class
Get Reduced Rates for Personal Car Rentals
Tracking Thomas at Jefferson Lab
JLab Calendar of Events
|JLab Weekly Briefs is an ongoing publication providing information on the status of safety, accelerator operations, experiments, free-electron laser, reviews, upcoming activities and special events. Deadline for submission is every Tuesday by 10 a.m. Submit new items to: Public Affairs or contact Kandice Carter at x7263.|