Jefferson Lab Weekly Briefs
July 14, 2010
12 GeV Upgrade
The second group of four Barrel Calorimeter (BCAL) modules for the Hall D GlueX spectrometer has arrived at JLab from the University of Regina, Saskatchewan, Canada. The third group of four BCAL modules have been built and sent for final machining in Regina. A successful readiness review for construction of the Hall D Forward Calorimeter was held at Indiana University. A new Cockcroft-Walton type high-voltage synthesizer-and-divider base has been prototyped there for the photomultiplier tubes that read out the 3,000 lead-glass blocks comprising the detector. The two large, precision endplates that support the 28 cylindrical layers of straw tubes of the Hall D Central Drift Chamber have been readied at Carnegie Mellon University, with first shipments of straws arriving this month. Tests of first-article preamps, using the custom ASIC preamp developed in collaboration with the University of Pennsylvania, have been coupled to the Forward Drift Chamber prototype at JLab. Operation of the new 72-channel 125 MHz pipelined flash analog to digital converter has also been tested in this setup with good results. Final manufacturing drawings for the Hall D tagger magnet and coil to be used in the upstream photon production area are being checked.
In Hall A, the test run for the so-called APEX experiment E-12-10-009, the search for a new vector boson, was successfully completed Monday morning. Thanks to a six-day extension, the run was able to address practically all of the issues that the PAC had raised and even obtained a limited data set of production quality. Hall A will now be open until late September for the transition to the two deeply virtual Compton scattering experiments, E07-007 and E08-025, scheduled for this fall.
The accelerator was running, with some downtime. A scheduled power outage last Tuesday and the subsequent recovery of beam took about 14 hours. On Wednesday, the accelerator was turned off to save power; beam was restored around midnight. Thursday day shift was used to perform accelerator beam studies. On Monday, the Central Helium Liquefier tripped and beam was recovered five hours later. By Monday morning, Hall A finished its APEX Test runs. Commissioning of Q-weak in Hall C continued; issues were being identified and addressed.
The FEL team continues preparations for ultraviolet lasing. The team took alignment measurements on the beamline before shutting down to break vacuum in preparation for the wiggler tube installation; however, a problem in wiggler tube fabrication was uncovered, which will delay its installation by one to two weeks.
A paper just submitted <arXiv:1007.0778> presents effective range expansions for the 1S0 and 3S1np scattering phase shifts and relativistic deuteron wave functions that accompany the recently published <Phys. Rev. C 78, 014005 (2008)> high-precision fits to the 2007 world np data. The wave functions are expanded in a series of analytical functions that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A FORTRAN subroutine to compute these wave functions can be obtained from the authors.
JLab's Safety Numbers
77 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
July 19-21: JLab ONP Facility Operations Review
Environment, Safety, Health & Quality
According to an "Occupational Health and Safety" magazine article, reducing hand injuries remains a challenge, even for companies that have done a good job of addressing hand hazards and providing the correct personal protective equipment. So what's the underlying problem? Exposure and attention.
Consider the number of exposures. A worker might lift, use tools, push or pull hundreds of times per day, with each task offering the potential for acute or cumulative injury. Additionally, the more someone engages in any activity, the greater the risk of complacency and the less likely the worker will be fully attentive of every movement.
The good news is, experience has shown it's possible to make significant improvements in preventing hand injuries with an approach that first puts workers in control of their own hand safety and then reinforces improvements in skills and actions. To keep your hands safe, work with ESH&Q to find the best PPE solution for your task, think ahead, find the best body position and maintain focus on the hazard.
Computing and Networking Infrastructure
Antivirus Software Upgrade Scheduled for Monday
Redhat Enterprise Linux Version 3 Support Ending
CEBAF Overview Talk
New SOTR Training And Certification Process
Test Lab Parking Lot Closure
American Red Cross Blood Drive