Jefferson Lab Weekly Briefs December 7, 2011
Jefferson Lab Weekly Briefs
December 7, 2011
12 GeV Upgrade
Hall B Update
The HDice target has been successfully installed in the CLAS detector in Hall B. The spin-polarized HD molecular target operates at or below 60 millikelvin in the "frozen-spin" mode. The deuterium atom in the HD target material is polarized at about 27 percent. The target is part of the G14-HD experiment that searches for predicted, but yet-to-be-discovered excited states of the neutron using the neutral Kaon-Lambda production channel. The target has been operating in the Hall B photon beam since last Thursday and shows no visible deterioration of its polarization. The measurement of polarization observables on nucleon targets is highly sensitive to interferences of resonant and non-resonant amplitudes, which enhance the visibility of weakly excited states. The successful construction and operation of the HDice target represents a major breakthrough in polarized target technology.
The Q-weak experiment is taking production data using the primary liquid hydrogen target and an aluminum target for background measurements. The Moller polarimeter, which was disassembled over the Six-Month Shutdown to replace a bad quadrupole, was recommissioned and used to measure beam polarization. The experiment was down briefly due to a failed high-power heater power supply. The power supply was replaced by a lower-power backup supply. Due to the very stable coolant supply from the Central Helium Liquefier and End Station Refrigerator, the target is still able to operate at full power (maximum beam current) while waiting for delivery of the replacement power supply.
The week started with Hall C receiving incrementally greater amounts of beam current up to 180 microamps. By midweek, Hall B came online with the production HDice target. Later in the week, injector optimizations to the electron bunch size allowed a cleaner path through the accelerator, resulting in a more consistent 180 microamps to Hall C. The weekend was smooth, except for a few hours lost Sunday due to a failed cooling water flow sensor, causing a loss of cooling water to each of the halls.
The DC power group continues preparing for first-article testing at JLab for the 12 GeV magnet power supply. The power supply was delivered just before Thanksgiving. The radiofrequency group is putting together a plan to restore operation of the new C100 RF systems in SL24 and SL25 for use during the present (high beam current) accelerator run. Valuable operating experience will be gained by running these 12 GeV RF systems in the coming months. Preparations are also underway to complete repairs on the 6 GeV RF system circulator loads, which developed water leaks following the long shutdown. More than 40 loads are being rebuilt and re-installed. The loads are needed to support RF operation at 5.6 GeV, which the physics program calls for after the holiday shutdown. Finally, all electrical support groups are completing check out of systems needed for the Hall A beamline commissioning run scheduled later this month.
Facilities Management & Logistics
Extensive JLab Power Outage Over Holiday Shutdown
JLab Calendar of Events
Dec. 10: JAG Children's Holiday Party
Environment, Safety, Health and Quality
Distracted Driving Can Claim Lives
JLab follows applicable state and national laws regarding the use of handheld devices by drivers while behind the wheel. "Texting while driving" is now against the law in Virginia and North Carolina and is banned nationwide for commercial vehicle drivers. The District of Columbia and Maryland have gone a step further, banning the use of all handheld devices by drivers while behind the wheel. Make sure you review the full list of state bans for the states you plan to drive in on your holiday travels. The list is available on the Distraction.gov website.
Computing and Networking Infrastructure
Computing Services Outage Will Precede Shutdown Power Outage
Mont on Awards
Annual Enrollment for TIAA-CREF 401(k) GSRA begins Thursday, Dec. 8.
Foreign Travel Medicine Program Requires Early Notice of Travel
Volunteers Needed to Help With Children’s Party
Usable Distribution Envelopes Needed
Automatic Teller Machine Replacement
Library to Hold Open House Dec. 16
Annual Children’s Holiday Party Set for Dec. 10
Toys For Tots Toy Drive Ends Dec. 10
Holiday Office Door/Cubicle Decorating Contest Underway
Personal Dosimeter Change Out Set for Dec. 19
Tracking Thomas at JLab
Congratulations this week go to Jason Willoughby and Samika Hawkins, who were the first to correctly identify the Nov. 30 location. An Honorable mention goes to Michelle Shinn. Check out the Tracking Thomas webpage for a better view of his last location and this week's new mystery photo.