Jefferson Lab Weekly Briefs
May 6, 2009
12 GeV Upgrade
The request for Best-and-Final Offers for the fabrication of the “Q1” superconducting quadrupole magnet for the new Super High Momentum Spectrometer in Hall C has been issued. This constitutes the first of the planned seven new superconducting magnets that will be procured. To initiate construction of the new CLAS12 wire chamber packages in Hall B, procurement of many of the component parts, such as wire and wire feedthroughs, has begun.
In Hall A, commissioning for the next two polarized helium-3 experiments, E05-015, A Measurement of the Quasi-Elastic Single Spin Asymmetry, and E08-005, Measuring the Transverse Asymmetry in the 3He(e,e'n) Reaction, has been successfully completed. Production running with 3-pass beam began April 29.
In Hall B, the damage on the polarized target that occurred during the insertion into CLAS last week has been fixed. The experiment has been ready to receive beam since April 29; after some startup problems, the beam was brought to the hall April 30, and first commissioning data have been taken. The data show excellent performance of the detectors. The target polarization is high (~80 percent).
Installation of the hypernuclear experiment continues in Hall C. The sieve slits for both the High Resolution Kaon Spectrometer and the High Resolution Electron Spectrometer are being installed, tested and aligned. The detector platform for the HKS has been placed. HKS and HES detectors are being tested in the Experimental Equipment Lab prior to installation in Hall C. The Hall C summer physics workshop is planned for August 6-7.
The accelerator was performing relatively well with a low trip rate. On April 29, Hall A was changed from 1-pass to 3-pass, and Hall B started to take 5-pass beam. The Arc4 box supply tripped off a few times, and investigation of the problem continued. The beam in the injector was having a slow drift, most likely caused by gun anode grounding; the problem was fixed. The insulating vacuum pump for zone 1L06 tripped off twice; the cause was identified, and the problem was corrected. Also, there was some routine maintenance on the radiofrequency system.
Free-Electron Laser (FEL)
The low-conductivity water line is being installed. Taking advantage of the gap in operations, FEL staffers are continuing installation work on the ultraviolet branch and replacing some diagnostics on the main machine. They have also been working to understand the location of the field emission in the gun, to increase the power and stability of the drive laser, and to improve the optical transport system.
A new Theory Center paper <arXiv:0905.0466 [hep-lat]> presents the results of an exploratory lattice QCD calculation of three-baryon systems through a high-statistics study of one ensemble of anisotropic clover gauge-field configurations at a pion mass of mπ ~ 390 MeV. The energy of a three baryon system is extracted for the first time, focusing for the most part on a system with the quantum numbers of two Ξ's and a neutron for computational expediency, but also providing first results for the channel containing the triton. This present work establishes a path to multi-baryon systems and shows that lattice QCD calculations of the properties and interactions of systems containing four and five baryons are now within sight.
JLab's Safety Numbers
121 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
May 20: JLab Annual Run-A-Round
Environment, Safety, Health & Quality
The Corrective Action Tracking System database now allows users to enter Facilities Work Orders as they enter their CATS items. Previously, all issues associated with a single CATS item had to be entered, saved and then re-typed into the FML system individually. In the improved configuration, a checkbox at the bottom of each individual issue entry allows users to create a Facilities Work Request. Additionally, all common information between the two systems is pre-populated within the FML system. This new functionality was implemented as a result of site feedback, specifically the CATS users group, and is intended to save time for CATS users.
Additionally, newly revised ESH&Q Manual chapters are now available on the JLab website. They include 6650 Engineered Nanoparticle Policy, 6650 Appendix T1 Miminum Mitigation Requirements for Engineered Nanoparticles, and 6650 Appendix T2 Emergency Procedure for Engineered Nanoparticles.
Computing and Networking Infrastructure
Computer User Audit Underway
JLab Community Mourns the Loss of Cornelius Bennhold
2009 Jefferson Activities Group Run-A-Round Set for May 20
Virginia’s Hurricane Preparedness Sales Tax Holiday
U.S. Postal Rates increase Monday, May 11