Jefferson Lab Weekly Briefs February 24, 2010
Jefferson Lab Weekly Briefs
February 24, 2010
12 GeV Upgrade
Construction on the solenoid and toroid magnets for CLAS12 in Hall B is proceeding at Wang NMR in California, with system and first manufacturing readiness reviews held in the past two months. Short sample tests of the superconducting cable for the solenoid are underway prior to preparation for winding. The support structure for a first sector of the region 2 drift chamber for CLAS12 has been assembled in the recently refurbished clean room at JLab. The wire stringing using this structure will start later this spring as a joint effort among Old Dominion University, Idaho State University and JLab. Test extrusions of scintillator for the Pre-Shower Calorimeter (PCAL) for CLAS12 recently concluded successfully at Fermilab, with the production extrusion to follow in the next months. Work on components for PCAL, such as photomultiplier tubes, wavelength-shifting fibers and splitters is proceeding apace at James Madison University, Norfolk State University, Ohio University and The College of William & Mary, all supported by a successful collaborative NSF-MRI grant.
In Hall C, installation for the Q-weak experiment continues. The region 3 rotator, which will hold wire chambers for tracking, has been installed downstream of the Q-weak toroidal magnet. A shielding wall with eight cutouts for scattered particles is being installed between the magnet and the rotator. Final preparations are underway for testing and mapping of the magnet. Restoration of the beamline has started, the four chicane magnets for the new Compton polarimeter have been placed, and the Moller polarimeter solenoid has been moved back into the beamline tunnel to its new location.
Announcing a Professional Networking Site for Physicists
The redesigned/rebuilt injector produced 121μA continuous wave current for the first time since all the changes were initiated. There was a combined DOE and JLab safety assessment tour during the week. Commissioning of the newly installed cryomodules in the North Linac is underway. Work was started on bringing the RF cavities in both linacs, wherever possible, into RF operation for the first time since the Scheduled Accelerator Down started. Overall, it is going very well. Hot checkout has begun of all accelerator systems; this is a critical part of preparing for scheduled beam operations on March 11. Personnel Safety System certifications are proceeding smoothly on swing shifts.
The shielding blocks are back in place at the FEL and the gun test stand. Optical cans for the ultraviolet system have been put in place and the new cryomodule is being hooked up to the radiofrequency system. Beamlines are back in place for the infrared and UV magnetic transport.
The Roper P11(1440) resonance is the lowest-lying excitation with the same quantum numbers as the nucleon; however, its properties have proven difficult to explain in terms of a simple three-quark structure. Recently, a relativistic quark model of the nucleon structure was extended to the Roper resonance <arXiv:1002.3386 [hep-ph]>, without introducing additional parameters, and applied to calculate the electromagnetic nucleon to Roper transition form factor. The model describes very well both the high-Q2 data (Q2 > 2 GeV2) and the lattice QCD data and is used to estimate the quark-antiquark content of the system that dominates at low Q2.
Facilities Management & Logistics
JLab Campus Electrical Change
Environment, Safety, Health & Quality
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Computing and Networking Infrastructure
Linux/Mac Printing Changes
New General Purpose Solaris System Available
JLab’s 2010 Benefits Open Enrollment Ends Tuesday
Annual T-Shirt Design Contest Underway
Free H1N1 Flu Vaccination Clinics Offered Locally
Restoration of the USS Monitor
SciGirls Shows Girls Digging Science
JLab's Safety Numbers
33 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Feb. 25: Safety Shoe Vendor onsite