Jefferson Lab Weekly Briefs February 22, 2017
Jefferson Lab Weekly Briefs
February 22, 2017
12 GeV Upgrade
The Torus magnet for CLAS12 was brought back down to liquid helium temperature at the end of January to prepare for the CLAS12 Key Performance Parameter beam commissioning run reported recently. The magnet operated without incident for the entire run. It was then kept at 4 Kelvin for two weeks to gain operational experience with the cryogenics and make incremental improvements to the control loops.
The central sections of the radiation shield of the Solenoid magnet have now been installed over the five coils making up the magnetic circuit and the resultant assembly covered with 25 layers of multilayer insulation. The entire cold mass was then again suspended from a temporary central support pipe and moved inside the barrel section of the outer vacuum cryostat, which itself had been placed in a support cradle that in turn will later serve as a shipping support fixture. The cold mass is suspended from the vacuum cryostat via eight thermally isolating support links, which are joined to the cryostat via specially shaped stainless-steel pockets that are now welded to the cryostat. The remaining sections of the radiation shield, which include the end cones, endcaps and central bore are being prepared by attaching their respective blankets of multi-layer insulation. The several dozen wires from the temperature and voltage sensors located on the Solenoid’s cold mass are being terminated in preparation to being attached to the main instrumentation feedthrough. The next major step is then transferring the load of the cold mass to the outer vacuum cryostat, after which the remaining sections of the radiation shield can be attached and the closure of the cryostat started. Planning for shipping the Solenoid to Jefferson Lab is well underway, with the shipping cradle being welded up prior to adding the isolation springs needed for the road trip to Virginia. The contract for the shipment has been awarded and includes a practice run with the shipping cradle in the near future over the highways to Pennsylvania in order to check g-forces encountered while driving along the roadway.
Jefferson Lab Published Journal Articles, Feb. 12-18
Publications Training Offered
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JSA/JLab Graduate Fellowship Program Now Taking Applications
Apply Now for Sabbatical and Research Leave Support at Jefferson Lab
Center for Theoretical and Computational Physics
Since the discovery of the J/Ψ meson over 40 years ago, production of heavy quarkonia is still arguably one of the most fascinating subjects in strong interaction physics, and theorists have not been able to fully understand its production mechanism. Within the non-relativistic QCD (NRQCD) approximation, the J/Ψ production cross section is often presented by summing over the production of various color-spin states of a pair of charm-anticharm quarks, weighted by NRQCD matrix elements characterizing the probabilities for the given states to transform into an observed J/Ψ. This new paper proposes and demonstrates that measuring the polarization of J/Ψ within a reconstructed jet provides not only a complementary measurement of, but also more stringent constraints on, the NRQCD matrix elements and the underlying J/Ψ production mechanism.
Environment, Safety, Health and Quality
Be Prepared to Run, Hide or Fight if Faced With an Active Threat Situation
If faced with an Active Threat situation – you see someone brandishing a gun or other weapon, or any implement being used to cause harm to people or lab facilities – you should consider yourself to be in immediate danger. To best protect yourself and colleagues, you will need to quickly take action appropriate for the situation you are in: Run, Hide or Fight.
For more information about each option and links to resources, see the full memo.
New Lab Director to Visit Feb. 21-23
JAG Seeks Design Ideas for 2017 JLab T-shirt Contest
Golf League Forming for 2017 Season; Interested Golfers to Meet on Feb. 23
Jefferson Lab Benefits Open Enrollment Ends Feb. 28
Reminder: Annual Property Training & Validation Due March 31
Jefferson Lab Calendar of Events
Feb. 24-25: Q-Weak Collaboration Meeting
|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: the Communications Office or contact Kandice Carter at x7263.|