Jefferson Lab Weekly Briefs
May 23, 2012
12 GeV UpgradeThe Hall D complex is being equipped with services and beamline items, including the pair spectrometer magnet and collimator system. The tagger magnet coils and steel cores are under production, with delivery expected in late summer. Wire-stringing of the straw tubes for the Central Drift Chamber (CDC) has been completed at Carnegie Mellon University. The third chamber package (of four total) is being built for the Forward Drift Chamber (FDC). The manufacturing contract for the several hundred FADC-125 read-out modules for the FDC and CDC is out for bid. A readout module for the Barrel Calorimeter (BCAL) has been extensively tested using beam parasitically during a Hall B run. The final units of the 3,840 silicon photo-multipliers for the BCAL are arriving, and machining and polishing of the similar number of lightguides is underway. Production quantities of high-voltage modules, low-voltage modules, cables, and VXS and VME-64 crates are arriving.
PhysicsData taking for Q-weak, the lab's most ambitious experiment to date, was completed in Hall C on Friday. During the long run, a large amount of parity-mode data was accumulated on the world's highest-power liquid hydrogen target. In addition, background and auxiliary measurements were made with a variety of targets, beam energies, beam conditions and Q-weak spectrometer settings. As well as being crucial to the extraction of the proton weak charge from the data, many of these measurements have a physics interest of their own. The success of the experiment was due to the efforts of the people, lab and collaboration that designed, built, installed, commissioned, operated and maintained the many components of the experiment, including the polarized source, accelerator, beamline, Compton polarimeter, cryogenics, target, Qtor magnet and the experimental apparatus. More than 20 graduate students have written or plan to write Ph.D. theses based on the Q-weak experiment.
AcceleratorAccelerator operations personnel started the week with a pass change for Hall A, from 2-pass to 3-pass beam. A bad power supply and controller board caused a phantom fault that would not clear (the fault propagated down the chain of controllers, but the source was not shown). This resulted in almost two hours of down time. A control module for a superconducting radiofrequency cavity failed, which required replacement and another two of the dwindling hours of 6 GeV beam time remaining. At the end of the day on Tuesday, the heavens opened up and the rain poured out. The end stations took the worst of it, with storm water flowing down the Hall B truck ramp, through the hall, and out into the other halls covering the floors in places with several inches of water. The accelerator remained dry but did have some glitches on several systems due to nearby lightning strikes. Personnel from Radiation Control, the Safety Systems Group and Engineering Support came in or stayed after to assist in the recovery, and beam was back to Hall A shortly after midnight, with Halls B and C coming up later that afternoon. A rack of magnet controllers for the injector had issues all week, with some magnets randomly failing to maintain the set currents. The operators became very efficient at recovering the magnets and restoring the beam, giving up only minutes of precious beam time as compared to the possible hours it may have taken to troubleshoot and repair the magnet rack. Thursday night at 8:30 p.m., beam was terminated to the halls. Hall C was changed to 3-pass beam, and the injector was set up for transverse spin polarization. The zone 2L25 C100 superconducting cavities were raised to 108 MeV and run with a total of 465 microamps for one hour, exceeding the 12 GeV Upgrade requirement for the new modules. On Friday, May 18, at 8:18:46, Lab Director Hugh Montgomery pushed the button that terminated the final 6 GeV beam.
Free-Electron LaserThe FEL team performed installation activities and some beam dynamics studies while awaiting delivery of a repaired wiggler controller. The machine achieved lasing while accelerating beam past crest, which is probably the first time anyone has accomplished this trick. Significant activities are underway in designing a robust gun and preparing superconducting radiofrequency cavities for reprocessing for the refurbished cryomodule.
Center for Theoretical and Computational PhysicsThe anomaly observed in recent quasi-elastic neutrino scattering data on carbon-12 — the excess of measured cross section relative to theoretical calculations — has led to speculations that our present understanding of the nuclear response to weak probes may be incomplete. However, the calculations that these speculations have been inferred from use rather crude models of nuclear structure and simplistic treatments of the reaction mechanism. In a new paper, inclusive neutrino scattering from the simplest nucleus, the deuteron, is studied over a wide energy range and within a realistic approach to nuclear dynamics. The motivations are twofold: the first is to provide a benchmark for quantum Monte Carlo studies of electro-weak inclusive response in light nuclei, including 12C, that will be carried out in the near future; the second has to do with plans to determine the neutrino flux in accelerator-based experiments from measurements of inclusive cross sections on the deuteron. Clearly, accurate predictions for these cross sections are crucial for a reliable determination of the flux.
EngineeringHall D Cryogenics Design and Installation
The 6,000-gallon liquid nitrogen dewar and 30,000-gallon warm helium gas storage tank have been installed on outside pedestals. The 4.5 Kelvin cold box and warm compressors have been moved into the building and are undergoing painting and some refurbishment. The fabrication shop completed building the warm gas management control valve rack. Fabrication continues on the cryogenic valve box that will sit on top of the four coils of the superconducting solenoid magnet and piping inside the plant building is beginning. The electronics racks, IOC/PLC-based control system and Linux workstation have been installed in the control room, and field cabling has been pulled into place and terminated on one end. Control software development is underway.
CHL2 Cryogenics Design and Installation
In the Central Helium Liquefier-2, work continues on the final phase of warm piping installation for the warm compressor systems. The electrical power, instrumentation and software for the main compressors have been completed and tested. The main 4,160-Volt, 800-horsepower and 2,500-hp compressor drive motors have been rotated. The instrument air and associated piping has been commissioned. The water piping system tie in to the water towers is nearly complete, and the oil and oil coalescer piping have been pressure tested. The inside and outside cold box sections of the large main 4.5 Kelvin refrigerator have been set in place, and piping and wiring installation has started. Linde and JLab are completing the safety plan for raising and installing the large sections of transfer line between the two cold box sections.
Environment, Safety, Health and QualityLimited Approach Boundaries
The Department of Energy continues to celebrate National Electrical Safety Month with a series of topics on electrical safety. In electrical works, a limited approach boundary is the distance from an exposed live part within which a shock hazard exists. The dimensions of this boundary change, based on the voltage and the type of conductor or circuit part that is present. The National Fire Protection Association 70E: Standard for Electrical Safety in the Workplace® contains Table 130.2(C), which lists the approach boundaries to live parts for shock protection. Unqualified persons must not cross the limited approach boundary unless escorted by a qualified person. See the link for a complete toolbox talk on this topic.
Get Your Hurricane Season Supplies - Tax Free!
The first named storm of 2012 has already churned the waters off the Eastern Seaboard, signaling the start of hurricane season. The Commonwealth of Virginia is offering a sales tax holiday for residents to stock up on hurricane preparedness supplies before the season gets into full swing. During the sales tax holiday, May 25-31, products including batteries, food storage containers, generators, first aid kits, bottled water, radios and other useful products that cost up to $60 may be purchased sales-tax free. Generators costing $1,000 or less are also included. For a complete list of allowable items, click the link. The list and other valuable resources can also be found on the Virginia Department of Emergency Management website.
Computing and Networking InfrastructureWeb Maintenance Period Set for Tuesday, May 29
The CNI group will be updating some web servers on May 29, 5-6 p.m. During this time, several web servers, including www, may be down for short periods of no more than 15 minutes. All web servers will be back up and stable no later than 7 p.m. If you have any questions, contact the IT Division Helpdesk at x7155.
Email Migrations into New System Continue
The CNI group is continuing to migrate staff and some users into the new email and calendar suite, Zimbra. These migrations are going well, with nearly 540 staff and users migrated into Zimbra and about 20 still left to migrate. Following the successful migration of the remaining users, the CNI group will review the list to make sure that everyone who should have been migrated has been. These migrations are occurring overnight, and you will receive an email around noon on the day you are scheduled to be migrated. For more information, see the article in the March 16 OnTarget newsletter.
AnnouncementsOpen House Pictures Posted to JLab's flickr Account
Pictures from JLab's highly successful Open House 2012: Passport to Science are now available for your perusal on the lab's flickr site. The collection may also be viewed by navigating to the site via the flickr link on the lab's home page.
New JLab Emergency Management Page Now Live!
Tina Menefee, JLab's Emergency Manager, announces the new JLab Emergency Management webpage, featuring a new design and updated content. Check out the resources and review the seasonal hurricane information at the Emergency Management webpage.
6 GeV End of an Era Party June 6 for Lab Staff, Students & Users
The Jefferson Activities Group is planning a 6 GeV End of an Era Party for JLab staff, students and users on Wednesday, June 6, 3:30 – 6 p.m. on the SURA Residence Facility field. The event will include food and drink, music and games. Come celebrate the end of an era (and the dawning of 12 GeV). Volunteers are needed to help with a variety of preparation, event and cleanup tasks. Visit the JAG webpage for more information and for the online volunteer signup page. For more information, contact JAG Chair Bridget Paul.
Tracking Thomas at JLab
Little Thomas is visiting all corners of the JLab campus. If you can identify his location this week, email Kandice Carter with your guess. Guesses are accepted through Friday.
Congratulations this week go to Michael Haddox-Schatz, Brita Hampton, Casey Heck and Samika Hawkins, who were the first to correctly identify the May 16 location. Honorable mentions go to Michelle Shinn, Maurizio Ungaro, Dana Cochran, Susan Brown, Jim Boyce, Stephanie Vermeire, Mike Legg, Greg Nowicki, Anusha Liyanage, Rob Mahurin and Andrea Celentano. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.
JLab Calendar of EventsMay 28: Memorial Day holiday, JLab closed
June 4: Safety Shoe vendor onsite
June 4-6: JLab Users Group Workshop and Annual Meeting
June 6: End of 6 GeV Era Party
June 18: Safety Shoe vendor onsite
June 18-22: Program Advisory Committee Meeting (PAC39)