JLab Weekly Briefs - August 11, 2016
Jefferson Lab Weekly Briefs
August 11, 2016
12 GeV Upgrade
The Torus magnet for CLAS12 has been pumping down the past several weeks and is now circulating cryogens. The pump-down took time because the gas being removed is about 80 percent water vapor, which is known to be slow to evolve from the multi-layer insulation in the vacuum space. This was addressed by using the nitrogen system that normally cools the radiation shields to instead circulate 340 Kelvin nitrogen to warm the MLI and help drive out the water vapor. In parallel, the cryogenics distribution can that serves as interface between the End Station Refrigerator and the two magnets in CLAS12 has been completed and checked, and the four U-tubes connecting it to the Torus Service Tower have been inserted. The second review required prior to the start of cool-down, to examine this cryo can plus all the supporting warm gas piping and vaporizers, has been completed and its recommendations addressed. The last review, to be allowed to energize the Torus, has been held and its recommendations are in the process of being addressed.
The two splices connecting the first and third, and the second and fourth, of the four "Field" coils of the CLAS12 Solenoid have been prepared, now that all the temperature and strain gauges have been added to these coils, after which the helium piping will be welded in place. The fifth, or "Shield", coil for the CLAS12 Solenoid is complete and is suspended in the specialized tooling used to mate it with the first four coils for the Solenoid. In that next major step, the five coils are joined into one assembly by suspending the bobbin with the four Field coils inside the bobbin for the Shield coil. This "cold mass" assembly is then covered with a radiation screen and multi-layer insulation. The final major step in building the Solenoid will involve insertion of this cold mass assembly into the outer vacuum cryostat, the outer shell of which is now at the magnet vendor’s site. The two conical parts of the end sections of the cryostat have been formed and welded to their respective cryostat end-plates, and the inner bore tube for the cryostat is prepared.
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Center for Theoretical and Computational Physics
Given the potential of CLAS and GlueX to generate high-precision data on light mesons, one of the projects undertaken at the Joint Physics Analysis Center has been to investigate the Dalitz decays of η mesons. This process is particularly interesting given that it is isospin-violating and sensitive to the difference of masses of the light u and d quarks. A new paper has combined the recently published, high-statistic KLOE-2 data together with the earlier data from WASA-at-COSY to perform an amplitude analysis based on dispersive methods, and obtained a new determination of the so-called Q parameter, Q = 21.6 ± 4, which is related to quark masses.
The Alignment group has been working on the following projects:
The Magnet Measurement group has been working on these projects:
Jefferson Lab Calendar of Events
Aug. 11: Jefferson Lab Employee Tour
Computing and Networking Infrastructure
IT Maintenance Day Set for Tuesday, Aug. 16
New Web Traffic Protections Launch on Tuesday, Aug. 23
Jefferson Lab Travelers and Travel Coordinators: Effective Immediately - Critical New Requirements for All Travel to or Passing through France
Reminder: Options to Save Time, Money in Procuring Materials for Your Next Project
Lastly, remember that when you plan to move property from one building to another for more than 30 days, you must notify Property Management, so that the item’s location is kept updated; this prevents the reporting of items that have been moved as missing.
Volunteer Opportunity: United Way Day of Caring
Department of Energy Sponsors Food Drive
Red Cross Blood Drive Scheduled for Tuesday, Aug. 16
Reminder: Hall C Safety Awareness Training Updated
|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.|