Jefferson Lab Weekly Briefs May 11, 2016
Jefferson Lab Weekly Briefs
May 11, 2016
12 GeV Upgrade
After effectively completing repairs, the cryogenic distribution box has been moved from the Technology and Engineering Development Building high bay to Hall B. The distribution box is now installed on the third level of the CLAS12 platform. Work is progressing on the pump-out of the Torus magnet in preparation for cool-down next month.
The French magnet factory, Sigmaphi, finished measuring the magnetic field produced by the Super High Momentum Spectrometer (SHMS) dipole magnet. It was run at low current with the coils at room temperature for these measurements. After the magnetic measurements and certification that the thermal-shield system was leak-free, Sigmaphi installed the vacuum vessel's inner bore tube and end plates, the last big pieces of the dipole magnet. Temporary seals will be used to allow a vacuum leak test of all internal systems prior to making the final structural weld. The dipole's cryo-control reservoir (CCR) has left Sigmaphi and is en route to Jefferson Lab. It will be joined to the magnet when they are both inside Hall C. The quadrupole magnets, Q2 and Q3, both now have complete thermal-shield systems, suspension links and fully connected superconducting current leads. The CCRs for the quadrupoles are already mounted in place above the magnets. On Q2, the helium pipes that join the magnet coil vessel to the CCR have been fully welded and inspected. Sigmaphi has finished the design and finite-element analysis of the frame that will support and protect the dipole during its journey to Hall C, while, at Jefferson Lab, the plan for moving, lifting and installing the magnet on the SHMS has now been drafted.
Center for Theoretical and Computational Physics
One of the challenges in quantum many-body physics is calculating the electroweak response of a nucleus by fully accounting for the dynamics of its constituent nucleons. A new paper reports the first such calculation for the electromagnetic response of the 12C nucleus. The results, which are in excellent agreement with experimental data, show that correlations in the initial ground state of 12C and interaction effects in the final states reduce the quasi-elastic peak of the longitudinal response by redistributing strength at low- and high-energy transfer. In the transverse sector, this quenching is offset by the contributions of two-body terms in the nuclear electromagnetic current, which substantially (by 30 percent at low momentum transfer) increase the response from the dominant one-body terms.
Jefferson Lab Calendar of Events
May 16-19: Precision Radiative Corrections for Next-Generation Experiments workshop
Environment, Health, Safety and Quality
PPE – The last mitigation to an electrical hazard
Computing and Networking Infrastructure
IT Systems Maintenance Set for Tuesday, May 17, 5-7 p.m.
Last Chance to Provide Your Feedback on the 2016 Jefferson Lab Open House
Workshop: Strategies for Planning, Developing, and Writing Large Team Grants
Run-A-Round T-Shirts Available for Distribution and Special Order until May 20
|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.|