Jefferson Lab Weekly Briefs July 11, 2012
Jefferson Lab Weekly Briefs
July 11, 2012
12 GeV Upgrade
The new SL23 zone (C100-5 cryomodule and new radiofrequency system) has been operated at 109 Megavolts in the linac; a full test with beam loading will be done later. Testing of the latest new zone (C100-4 and associated new RF) has begun. Deliveries of new klystrons now exceed the 80 needed for the 12 GeV installations. Removal of the beamlines from the tunnel is making good progress: the east and west recombiners and the west spreader have been removed; removal of the east spreader is underway. The first fully reworked spreader/recombiner dipole magnet, which included modification to the iron core, has been tested; field measurements were within specifications, giving further validation to the design model used for these complicated magnets. All M15 and M20 beam position monitors are ready for installation on the new beamline girders. Progress on the Hall D 4.5 Kelvin refrigerator continues, with installation of the pan legs and nitrogen separator. The vendors for the major components of the Central Helium Liquefier-2 4.5 K plant are on-site completing their work, including installing the very large transfer line for the coldbox. All of the high-voltage power supplies for the beamline ion pumps have been received.
With 6 GeV de-installation essentially complete, a program of necessary maintenance and repair work in Hall A is underway. Efforts directed at first 11 GeV era experiments has begun, with work progressing on the beamline and Compton and Moller polarimeters.
In Hall C, the Q-weak target has been removed from the beamline, and other Q-weak de-installation work continues, including the removal of the Qtor power supply and many shielding blocks from the hall.
Operations of the injector ended on June 29 with two days of beam studies after the successful run of the PEPPo experiment. LSD activities are in full swing in the accelerator enclosures, buildings and in the halls. The Test Lab was vacated by Superconducting Radiofrequency Institute personnel and equipment on July 2, and after a few days of preparation, the main demolition work in the Test Lab starts this week. SRF personnel are now fully focused on the challenging task of getting the new Test Lab Addition (TLA) ready to support SRF activities and production again: rooms needs to be certified, equipment must be reconnected and recommissioned, and all that requires an enormous amount of coordination and cooperation within SRF and the entire laboratory.
The FEL team had a very good start of operations of the infrared beamline with the DarkLight experiment in place and was even able to set up the beam to allow an initial target insertion. The team was able to get the beam cleanly through the 6 mm aperture and is presently optimizing the machine for transmission through the 2 mm aperture.
Center for Theoretical and Computational Physics
A collaboration of theorists and experimentalists from JLab and Hampton University has completed an analysis of the impact of the nuclear dependence of the longitudinal to transverse cross section ratio R=σL/σT on the extraction of ratios of structure functions of heavy nuclei (A) to those of deuterium (D), F1A/F1D and F2A/F2D. Guided by world data indications of a small enhancement of R in nuclei compared to hydrogen, the analysis of selected EMC, BCDMS, NMC and SLAC data sets revealed that the nuclear enhancement (antishadowing) for F1A/F1D in the interval 0.1 < x < 0.3 becomes significantly reduced, suggesting that antishadowing is dominated by the longitudinal structure function, FL. Precise measurements of nuclear modifications of R and FL, including those at JLab, have the potential to constrain the poorly known gluon distribution in nuclei over a wide range of x.
Hall D Cryogenics Design and Installation
CHL2 Warm Compressor and Warm Gas/Oil/Water/Air Management Systems
CHL2 300 - 4.5 K Coldbox Systems
CHL and Linac Summer Shutdown
End Station Refrigerator and Cryomodule Test Facility Refrigerator
Environment, Safety, Health and Quality
Resolving ES&H Concerns
Once your concern has been addressed, communicate any lessons learned to your staff, co-workers, supervisors and your Division Lessons Learned Coordinator. ES&H Manual Chapter 2310 offers more information on concern resolution.
Computing and Networking Infrastructure
CNI Systems Maintenance Set for Tuesday, July 17, 5-10 p.m.
JSA Initiatives Fund Proposals Due
Lab Voluntary Separation Program Application Deadline Approaching
Tracking Thomas at JLab
Congratulations this week go to Harry Fanning, Michael Haddox-Schatz and Jim Follkie, who were the first to correctly identify the location for June 27. Honorable mentions go to Jason Willoughby, Subashini De Silva, Dave Fazenbaker, Dick Owen, Russell Mammei and Chris Perry. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.
JLab Calendar of Events
July 9-13: Geant4 Tutorial