Jefferson Lab Weekly Briefs January 28, 2009
Jefferson Lab Weekly Briefs
January 28, 2009
12 GeV Upgrade
A review of the movable support carriage for the five superconducting magnets and the shield house for the detector package of Hall C’s Super High Momentum Spectrometer was held in December. The committee expressed a high confidence level in the design team and validated the feasibility of the design. There were no recommendations, but a detailed list of observations was given as a punch list for completing the reference design for the procurement phase.
In Hall A, experiments E06-010, Measurement of Single Target-Spin Asymmetry in Semi-Inclusive Pion- Electroproduction on a Transversely Polarized 3He Target, and E07-013, Target Normal Single-Spin Asymmetry in Inclusive DIS n(e,e') with a polarized 3He Target, have resumed taking production data, two days earlier than on the schedule. E06-010 is on schedule, E07-013, running parasitically, will obtain a poorer accuracy than projected due to the late availability of the BigBite gas Cerenkov detector.
Hall B is in the process of successfully completing the e1-dvcs run. More than 90% of the anticipated data will have been collected by the end of the run. Preparations are underway for the eg1-dvcs run, which will also use a polarized NH3 target.
After some initial problems with quenches at low currents, the polarized target magnet used by the Spin Assymmetries of the Nucleon (SANE) experiment in Hall C has been successfully ramped to full current several times. During operations with the magnet, the refrigerator, which cools the polarized material to 1 Kelvin, was found to have internal leaks that prevented it from functioning. The refrigerator was removed (this can be done with the magnet cold), but repairs were not successful. A spare refrigerator was brought from UVA. After minor modifications to adapt it to the installed target, this refrigerator was installed and is functioning well. SANE is now taking checkout and calibration data and plans to polarize the NH3 target material soon in order to start production data taking.
The accelerator has been running well. The cavities have also performed well, with low trip rates. Seven hours were spent on Tuesday for machine development beam studies. An unstable Arc4 magnet power supply caused several hours of downtime in order to diagnose and make repairs.
Free-Electron Laser (FEL)
The FEL operated well every day during the week, and FEL staffers made good progress on an important study related to off-axis injection of the electron beam from the injector into the linac. Staff from the FEL Div. and SRF Institute completed initial testing of a new cryounit and observed great performance, including a record maximum acceleration gradient of 32 MV/m in pulsed operation for one of the cavities.
An area presently attracting intense interest, both experimental and theoretical, is the relationship between the spin of the proton and the spins and orbital angular momenta of its constituents. While remarkable progress has been made, especially in the last decade, the discovery and investigation of new concepts have revealed that much more remains to be learned. This progress is discussed in a new, non-technical review article (arXiv:0812.2208 [hep-ph]), and an outlook for the future is offered.
JLab's Safety Numbers
23 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Jan. 26-30: PAC 34
Environment, Safety, Health & Quality
Be aware that ES&H Manual Chapter 6122 Appendix T2 Fire Protection: Hot Work Permit has been revised. The most significant change deals with Hot Work Permit sign-offs. Previously, supervisors could issue, sign and post hot work permits; the recently approved guidance now requires that the lab's Fire Protection Engineer, Dave Kausch, sign off and post all hot work permits. This change was driven by a finding from the recent Fire Protection Program Assessment and allows the site owner of the Sprinkler and Fire Alarm Systems to maintain awareness and control of conditions that could affect both systems.
Hot Work Permits can be completed electronically and e-mailed to Dave Kausch, at which point he will print, sign and post the document in the appropriate area. If he is offsite, John Reisbeck and Bob Rice, in that order, have sign off and posting authority.
Computing and Networking Infrastructure (CNI)
JLab Computer Purchasing Policy (EPEAT)
General Access RWP Due Jan. 30 for All Radiation Workers
JLab Meeting Rooms Locked After Core Business Hours for Property Protection
Security Refresher Due by Jan. 30 for JLab Staff and Students
Tech Stockroom Reopens Feb. 1
Come Out and Play on the JLab Softball Team
Be a BEAMS Volunteer!
American Red Cross Blood Drive Results
HRSD Seeks Applications for Pollution Prevention Award