Jefferson Lab Weekly Briefs July 29, 2009
Jefferson Lab Weekly Briefs
July 29, 2009
12 GeV Upgrade
The first superconducting magnet contract (for the Hall C/SHMS Q1 magnet) was awarded July 10, thus completing an important milestone in the project plan. Hall D recently held reviews of two of their subsystems. A review committee validated the tagger magnet final design and advised the team to finalize the detailing in-house rather than incorporating it into the construction contract award. A second review committee evaluated two readout choices of the Barrel Calorimeter detector. Committee members felt the first readout option, with silicon photomultipliers, looked very promising and recommended a test plan be developed for final certification and quality assurance of prototypes during the remainder of this calendar year. The more conventional backup option with fine-mesh photomultiplier readout was again found to be viable with a sufficiently detailed implementation plan, if needed.
The Scheduled Accelerator Down period continued with maintenance on RF (radiofrequency) systems, magnets, the vacuum system, the control system, the personnel safety system and more. On July 22, a hurricane power test was conducted and some problems were identified. The accelerator sprinkler system was tested. On July 25, beam was steered up to the 500 KeV dump in the injector.
FEL staff performed some key measurements this week on optical coatings. Last Friday, the team held a User Workshop in support of plans for a Soft X-ray capability of the FEL called JLAMP. The plans were well received and the group is developing a science case for presenting it to DOE.
A new paper <arXiv:0907.2395> derives mass corrections for semi-inclusive deep-inelastic scattering of electrons from nucleons, using a framework which incorporates the initial state mass of the target nucleon and the final state mass of the produced hadron. The hadron mass corrections are made by introducing a generalized, finite-Q2 scaling variable for the hadron fragmentation function and are found to be even larger than for inclusive structure functions. The mass corrections compete with the experimental uncertainties at kinematics typical of JLab experiments and will be important to efforts at extracting parton distributions or fragmentation functions from semi-inclusive processes at intermediate energies.
JLab's Safety Numbers
14 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
July 29: American Red Cross Blood Drive
Environment, Safety, Health & Quality
Many JLab personnel have personal electric appliances in their cubes, trailers or offices. Here are some general tips to keep these types of items safe both at work and at home:
Today: American Red Cross Blood Drive
New JLab Video: Special Viewing Today
Free DVD copies of the video will be available for pick up afterward in the CEBAF Center lobby. One per person, please. The video may also be viewed online.
Visit JLab Summer Poster Session