Jefferson Lab Weekly Briefs February 6, 2008
Jefferson Lab Weekly Briefs
February 6, 2008
12 GeV Upgrade
Design effort on the conventional facilities to support the 12 GeV CEBAF Upgrade continues to progress. The 100 percent design package for the Beam Switchyard (BSY) Service Building Addition was completed by the JLab Facilities Design Team. This is an internal addition in Building 98 that expands the power supply room into the welding area and includes two new penetrations into the accelerator tunnel. The package has been distributed for an internal design and safety review, and a meeting to discuss the review findings is scheduled for Feb. 13. Also, JLab Facilities has reviewed the first draft of the Hall D Complex Commissioning Plan developed by a local construction management firm.
Hall A successfully ran a series of tests for the lead-parity experiment E06-002 that included proving that the lead-diamond sandwich target could withstand a current of up to 100 microamps and commissioning two prototypes of the detector installed in the High Resolution Spectrometer focal-plane. On Feb. 4, the installation for the upcoming experiment on threshold pi-zero production started.
This period was very busy for the accelerator. It started with beam delivery to all halls (total beam delivered was 123 hours.) The beam current intensity was up to 100 microamps for Hall A, 15 nanoamps for Hall B and 40 microamps for Hall C. Things went well until Jan. 29, when a vacuum problem appeared in Hall C. The hall remained offline for the rest of this reporting period due to troubleshooting efforts on this vacuum problem. A pass change was performed on Jan. 30. Beam delivery continued until another energy/pass change on Feb. 1, in preparation for extended beam studies that began with beam break up (BBU) test plans on Feb. 2 and also included Optical Diffraction Radiation (ODR) installation and characterization in Hall A. Over the next three days, there was a total of 45 hours of test plans, and three energy/pass changes were accomplished.
Free-Electron Laser (FEL)
The gun processing on the Gun Test Stand is proceeding well, with the gun above 480 kilovolts (kV). The FEL gun is also reassembled and is preparing for high-voltage processing. In parallel with the gun work, checkouts of the various FEL systems are being performed and items that have become inoperable during the shutdown are being fixed. Major progress was made on the Laser Personnel Safety System Master Controller by completing the wiring and getting it to communicate to the EPICS control system. Several personnel participated in a 4th generation light source workshop and planning meeting at LSU. This week, several valuable pieces of bioscience laboratory equipment became available to the Eastern Virginia Medical School/JLab collaboration. Collaborators at EVMS (Jorge Jacot, Frank Lattanzio, and Bill Wasilenko) arranged for EVMS to loan this equipment to the JLab FEL program.
Parity-violating deep inelastic scattering has recently been proposed as an important new tool to study aspects of the quark structure of nucleons, such as the ratio of the down/up quark distributions at large Bjorken-x and charge symmetry violation in quark distributions, as well as physics beyond the standard model. At low values of Q2, however, corrections to the PVDIS asymmetries arise from kinematical effects and longitudinal contributions to photon-Z boson interference. A new paper explores these finite-Q2 effects and gives estimates of the corrections to planned JLab PVDIS experiments at 6 and 12 GeV.
JLab's Safety Numbers
140 Days since Last Recordable Accident (JLab record: 319)
Continuously improving safety at JLab
JLab Calendar of Events
Feb. 6: Colloquium, CEBAF Center auditorium, 4 p.m.
Environment, Safety, Health & Quality
Many of us have noticed an increasing number of laptop computers in use at JLab. Laptops can have the power of a desktop, while weighing far less. Although extremely convenient, laptop computers do have potential ergonomic problems. A keyboard in a well-designed computer workstation should sit low and tilt downward toward the user. The screen top should sit near eye height. Meeting these criteria takes work because of the connection of the keyboard and screen. Setting the laptop on a stand that tilts the base down in front and up in back can help. Laptop users are also urged to take several stretch breaks per hour and to avoid resting their forearms on sharp-edged work surfaces. Skin burns, equipment damage and fire have occurred during the use of some laptops. Laptop users are encouraged to make sure they have adequate space below their computers, unblock ventilation ports and make sure that cooling fans are running.
Shelving Collapse "Near Miss"
Computing and Networking Infrastructure
CNI Maintenance Day is scheduled for Feb. 12
Feb. 12 e-mail changes to impact users of Pine, Mutt and mailx clients
The changes that will take place are two-fold:
Additional changes that will affect all users and where you store your e-mail folders will take place later in the spring/summer. Announcements will be made regarding those changes at a later date.
Automatic Installation of Microsoft Office on March 4
Pollution Prevention Award Nominees Sought
JAG Dog Sports Training Club Informational Meeting
Come Out and Play on the JLab Softball Team