Jefferson Lab Weekly Briefs February 3, 2016
Jefferson Lab Weekly Briefs
February 3, 2016
12 GeV Upgrade
The main support legs have been installed on the Torus magnet for CLAS12 that is being assembled in Hall B. The weight of the magnet has been transferred to the legs, following which the assembly “spit” and its two blue support stands have been removed. Next steps include a detailed survey and then adjustment of the positions of the magnet coils proper, relative to the vacuum jackets. Once this is complete, the thermal shield and hub cryostat can be added to the currently exposed cold hub at the center of the magnet. The Torus Service Tower will be added at that point. It supplies cryogens to the magnet and also serves as a cooled conduit for the two main power leads and for the various instrumentation wires coming from the magnet internals and measuring pressures, temperatures and voltages across splices. The Distribution Can for cryogens, which acts as the interface between both magnets and the End Station Refrigerator, is undergoing final manufacturing checks at the vendor in Chicago. The in-field checkout has begun for the control logic and instrument readouts for the magnet, and ordering, testing and installation of the various parts of the vacuum pumping system is well underway.
The vendor for the Solenoid magnet for CLAS12 has epoxy-impregnated both of the two “Intermediate” coils. Preparations and trial runs are underway for the major subsequent step, which is cooling the two Inner coils and then inserting them into machined cavities in the winding bobbin for the Intermediate coils to form the main four-coil winding pack for the Solenoid. The bobbin for the fifth, or “Shield”, coil has been delivered to the vendor and set up on the winding machine. Insulating layers and the guide pieces for the power leads are being attached to this bobbin, after which the Shield coil will be wound and then epoxy-impregnated. The parts for the Solenoid cold mass assembly are on order in anticipation of the next step in Solenoid assembly after Shield coil winding is complete. In this step, the five coils are joined into one assembly by suspending the bobbin with the four Inner and Intermediate coils inside of 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, which is being procured.
Jefferson Lab Published Journal Articles, Jan. 25-29
Remember to submit your papers for approval to the Jefferson Lab Publications database.
Publications Refresher Course Offered Feb. 23
Apply Now for the Graduate Fellowship Program at Jefferson Lab
JSA Offers Sabbatical and Research Leave Support at Jefferson Lab
JSA Thesis Prize Call for Nominations
2016 L’Oréal USA For Women in Science Fellowship Program Now Accepting Applications
Center for Theoretical and Computational Physics
The Jefferson Lab Angular Momentum (JAM) Collaboration has completed a comprehensive new global QCD analysis of polarized deep-inelastic scattering, including the latest data on polarization asymmetries from Jefferson Lab. The analysis is performed using a new iterative Monte Carlo fitting technique which generates stable fits to polarized parton distribution functions (PDFs) with statistically rigorous uncertainties. Inclusion of the Jefferson Lab data leads to reduced PDF errors for the valence and sea quarks, and for the gluon at large momentum fractions, and provides the first detailed extraction of the twist-3 PDFs describing chromo-electric and -magnetic forces in the nucleon.
The Survey and Alignment group has been busy. Hall D's polarimeter was calibrated and aligned and the target/spectrometer were checked and aligned. In Hall C, the dump monument control was updated to support the installation of the new dump, and the 12 GeV components were aligned for final alignment. For Hall B the following work was completed or being worked on: the PRad target vessel was fiducialized and prealigned; the survey monuments were leveled to the upstream beam switchyard; the Low Threshold Cherenkov Counter and Panel 2A supports were measured and are being aligned; the torus was measured and checked prior to the spit being removed; and the Heavy Photon Search experiment components were aligned for weekend runs. For Hall A, the Gas Ring Imaging Cherenkov detector was inspected. Finally, after the accelerator was opened, a complete survey of the survey network was carried out to monitor tunnel movements.
Environment, Health, Safety and Quality
Bypassed Safety Features
So what can Jefferson Lab learn from these events? One lesson is to work only on systems for which you are currently trained and authorized. It is imperative that one know what a lockout really controls and whether other systems can still affect where you are working. Before you begin working on a system, make sure you are familiar with the system and that you verify that each lockout is in place to protect yourself and your coworkers. Finally, never ignore or bypass any warning signs on equipment.
Computing and Networking Infrastructure
Jefferson Lab Wireless Outage
Computer User Account Request Form Online Feb. 10
User Account Audit Beginning Feb. 15
Main Sidewalk from CEBAF Center Circle to TED is Closed to All Pedestrians until Further Notice
Quark Cafe Offers Special Menus for February Events
Science Series: What Every Dog Should Know About Quantum Physics
JAG Dog Training Club to Kick off New Session at the Feb. 9 Science Series Talk; Training Classes to Begin on Feb. 23
Jefferson Lab Entrance Closure on Feb. 15: Lawrence Drive
Jefferson Lab Calendar of Events
Feb. 6: Va. Regional High School Science Bowl
|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.|