Jefferson Lab Weekly Briefs
June 24, 2009
12 GeV Upgrade
The 12 GeV Accelerator Systems teams continue to focus on placing construction contracts.The vendor proposals are under review for “C”-dipoles (used in the spreaders and recombiners), septa dipoles and quadrupole magnets for the beam transport system. Both dipole contracts will include magnets for the extraction system. The contract to build the niobium accelerating cavities for the cryomodule system is nearing award. The contract for the 4.5 Kelvin coldbox for the helium refrigerator expansion is nearing award, and the Request-for-Information (RFI) has been released for the associated warm helium compressors. The cathode power supply contract and the box supply contract are under development. The former provides the raw power for the klystrons that will energize the accelerating cavities in the cryomodules, and the latter will power the larger dipoles in the recirculation arcs and beam transport lines to the halls. A design review was held for an alternate option for the spreader/recombiner layouts, optics and magnets. Some engineering and designer resources have been shifted from the beam transport work to the extraction system, with the goal of completing all extraction design work by mid-August.
In Hall A, Experiment E05-102, Measuring the Transverse Asymmetries in the 3He(e,e'd) Reaction, has successfully accumulated all the required data. The summer down has started, in which the polarized 3He target and the BigBite spectrometer have to be removed and the standard cryotarget has to be installed. In parallel, the Moeller polarimeter will be upgraded.
In Hall C, installation of beamline chicane magnets for the hypernulcear experiment has started. The entire detector package for the High Resolution Kaon Spectrometer has been placed in the detector hut. Most of the cable trays have been installed in preparation for connection of power and water to the spectrometer magnets and connection of signal and high-voltage cables for the detectors.
This period started with the accelerator being set up to deliver more than 6 GeV. This was a test setup for two experiments later in the schedule (both starting in late October). With support from injector staff (setting up the injector for 100 microamps), the test was successful with 100 microamp, continuous wave beam briefly delivered to the Hall A beam dump. More work is needed on this setup before smooth production beam can be delivered, but it was a great start!
The Scheduled Accelerator Down started with a safety briefing for all accelerator staff in the CEBAF auditorium. The Central Helium Liquefier experienced several trips and staffers were in the process of troubleshooting the problem, focusing their efforts on the magnetic bearings of several compressors. A failed temperature sensor was found and bypassed. Maintenance work is underway around the accelerator and is proceeding smoothly.
Significant effort was put in to re-establish full-power lasing capability. Although 1.5 days of running were lost to cryogenic and power work onsite, lasing has been re-established on the system. The FEL team also received an announcement of award of its first DOE Basic Energy Sciences grant ($900K) for development and testing of advanced superconducting cavity designs in the FEL injector.
The pion cloud of the nucleon is known to play an important role in the nucleon's long-range structure, yet computing its effects consistently in different frameworks has often been challenging. A new Theory Center paper <http://arXiv.org/abs/0906.3497> demonstrates the equivalence of pionic corrections calculated on the light-front and in equal-time quantization, as well as in a manifestly covariant formulation, using the nucleon's self-energy as an example. It shows for the first time that the leading and next-to-leading nonanalytic behavior of the self-energy is independent of the method used to evaluate it, placing the computation of pion loop effects on a firmer theoretical footing.
JLab's Safety Numbers
170 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
June 24: JLab Colloquium and Public Lecture, CC auditorium, 4 p.m.
Environment, Safety, Health & Quality
Trend analysis of JLab medical events over the past year shows that eight of 24 reported events involved cuts or lacerations to the hands, fingers or thumbs. Feedback to JLab’s Occupational Medicine group has included comments such as “I was moving equipment” and “I was pulling cable.” This level of hand-related medical events warrants further attention and should be addressed in individual work plans, task hazard analyses or departmental policies.
Please remember that when planning or conducting work, review inconspicuous hazards such as burrs, frayed cables and sharp edges, and take the appropriate precautions, such as wearing gloves or taping edges. Observe the work being conducted around you and pass on suggestions for safer work practices to both individual workers and management.
In summary, plan for all hazards, whether minor or major. Continue to report all medically related events, in order to learn from and maintain high levels of safety awareness.
Beginning July 20, an assessment on the JLab Lessons Learned program will be conducted by independent contractors. The assessment will take approximately four days and involve personnel from several divisions. It will focus on JLab's use of Lessons Learned, how they prevent injuries at JLab and the extent to which we share lessons with other sites.
JLab Dosimeter Changeout Set for This Weekend
Remember to return your dosimeter to its place in the assigned rack when it is not in use. Don't leave it in your desk or other work area. Don't leave it in your car or where it will be exposed to direct sunlight.
American Red Cross Blood Drive
Don't Get Scraped
Never provide the username and password to your JLab account or any other e-mail account you may have to a third party, such as a social networking site. Any time you receive an e-mail from a social networking site that you are unfamiliar with or are not already affiliated with, be sure to check with the person that supposedly invited you to join to make sure the invitation is legitimate. Also, read the fine print in the membership rules before joining a site.
Calling all CEBAF History Buffs!