Jefferson Lab Weekly Briefs March 11, 2009
Jefferson Lab Weekly Briefs
March 11, 2009
12 GeV Upgrade
The construction contractor for the Central Helium Liquefier building addition is finalizing administrative submittals to obtain approval for onsite work. The first phase of the work is relocation of a fire hydrant and expansion of the asphalt pavement on the east side of the existing CHL building. Phase 1 work is scheduled to start in April and has a one-month duration. Upon completion of Phase 1, the Cryogenics Group will relocate the helium tube trailer to the east side of the CHL building.
In Hall A, after losing more than three days of beam, experiment E06-014, Precision Measurements of the Neutron d2, resumed stable production running and is expected to reach its goals with the four-day extension to March 16.
Hall B continues to run the eg1-dvcs experiment using an extremely well-performing polarized target. The extension of the run until March 16 will allow experimenters to collect the data expected for this run period. The CLAS collaboration had a very successful meeting on the physics program of the upgraded CLAS12 detector for the JLab 12GeV Upgrade. About 120 people participated in the meeting, discussing exciting physics perspectives for CLAS12, the upgraded CLAS detector for 12 GeV. Representatives of the French, Italian and European funding agencies presented talks on their support of the JLab upgrade.
The Spin Asymmetries of the Nucleon Experiment in Hall C has completed measurements of scattering asymmetries with the proton target polarization oriented perpendicular to the beam. For both 4.7 GeV and 5.9 GeV running, the experiment obtained about 75 percent of the statistics planned in the proposal. The remainder of the running time will be dedicated to running with the target polarization parallel to the beam at both 4.7 and 5.9 GeV.
Last week, the accelerator started off well, but the performance was affected later by some magnet box supplies and the beamline vacuum at 1L04. Three box supplies each tripped off a couple of times during the week. On Friday, the passes for both Halls A and C were changed and so was the Wien angle. On Sunday, the vacuum at 1L04 started to deteriorate. Early Monday, the vacuum at 1L04 was getting worse and beam delivery was interrupted. As of Tuesday morning, the recovery of the vacuum was still in progress.
Free-Electron Laser (FEL)
FEL staff had a good week of running despite a slow start due to snow days. Staffers provided light in the user labs on several days, doing some demonstrations of beam profiles in acrylic. The team continues to acquire interesting mirror performance data. The director of the Office of Naval Research was hosted for a visit on Friday.
A new paper (arXiv:0902.4256 [nucl-th]) explores quark-hadron duality in semi-inclusive pion electroproduction on proton and neutron targets. Using the spin-flavor symmetric quark model, ratios of pi+ and pi- cross sections are computed for both unpolarized and polarized scattering and realizations of duality in several symmetry-breaking scenarios are discussed. The model calculations allow one to understand some of the key features of recent JLab data on semi-inclusive pion production at low energies.
JLab's Safety Numbers
65 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
March 11: JLab Colloquium in CC auditorium, 4 p.m.
Environment, Safety, Health & Quality
An incident involving an undocumented work restriction was recently investigated. A worker with a heightened sensitivity to certain fumes was transferred to another department. He and his previous supervisor had an informal agreement that if fume exposure caused issues, his work would be relocated out of the affected area. This occurred approximately once every three months. Previously, the worker had been verbally instructed by a physician to avoid these types of fumes; however, there was no formal work restriction issued by either this physician or by JLab's Occupational Medicine Department.
The undocumented medical restriction information was not made known to the new supervisor. Subsequently, fume exposure occurred, which resulted in a work-related medical issue. The investigative team solicited feedback for corrective actions; these actions address issues such as employee and supervisor feedback to Occupational Medicine staff of emerging medical conditions, as well as Occupational Medicine staff followup on emerging issues during each employee's triennial physical examination.
Please remember that safety is everyone's responsibility; provide feedback to both your supervisor and Occupational Medicine if you have emerging medical issues and obtain the necessary restrictions if they will impact your work.
Computing and Networking Infrastructure (CNI)
CNI Maintenance Period Set for Tuesday, March 17
Default Settings for Windows Printers to Change
E-mail Outage and Reconfiguration Begins Friday, March 20, 10 p.m. Through 3 p.m., Saturday, March 21
The location of e-mail folders is being changed. Currently, JLab account holders have e-mail folders that are stored in their home directories (/home/user on Unix or J: drive on Windows). The reconfiguration will move these folders out of account holders' home directories and place them on a standalone, isolated file system. Account holders will not have direct access to this new file system. All access to these folders will require an IMAP mail client (i.e. Thunderbird, Pine configured as an IMAP client, etc). Further information about this reconfiguration will be available on the CNI group web page as the date approaches.
jlab.org Alias Change
Mathematica 7 Now Available
Pager System Upgrade
Come and Join the JAG Dog Training Club!
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