Jefferson Lab Weekly Briefs
October 14, 2009
12 GeV Upgrade
Construction continues on the first barrel calorimeter module for Hall D, with lead- and fiber-layered assembly now complete at the University of Regina in Saskatchewan, Canada, and machining of the assembled module started. One quarter of the total fibers needed for this detector have now been received, with all samples passing quality assurance checks. The endplate for the central drift chamber detector for Hall D has been released for fabrication, and construction of the prototype layers for the forward drift chamber is proceeding at JLab.
A meeting was held at JLab to plan construction of a complete prototype chain, from sensors to data acquisition, of the silicon vertex tracker for Hall B. The bid process has begun for the five large power supplies needed for the Hall C Super High Momentum Spectrometer superconducting magnets.
In Hall C, the hypernuclear experiment continues production data taking, with recent data taking using lithium and boron targets. A polyethylene (CH2) target has been installed in order to perform optics and missing mass calibration with Lambda production on hydrogen. With the approach of the Q-weak installation period, the Q-weak toroidal magnet (QTOR) spectrometer has been disassembled at MIT/Bates and shipped to JLab. The eight copper coils, weighing 12,000 pounds each, have arrived and are being fiducialized before being moved to the hall.
REVTeX 4.1 Released
APS April Meeting Abstract Submission Deadline is Oct. 23
Operations personnel delivered beam to the halls with some down times. On Thursday, the Central Helium Liquefier tripped due to a failed uninterruptable power supply. The injector was optimized to deliver high current to Hall C. Time was also spent to optimize the injector to stabilize the beam on a couple of occasions. It appeared that beam in the injector had been drifting for a few days, but the root cause of the drifting has not been identified. Beam has been stable since Monday evening after some injector tuning.
The FEL ran extremely well again this week. New operating conditions were investigated, and good lasing took place at 3.86 and 3.4 microns. In addition, the FEL team ran beam into user lab 6 and confirmed that all nine optics were performing well. The team is preparing for the first electron beam through the ultraviolet transport line. A short in one of the UV magnets was located and repaired, and the team is preparing to measure the fields in all the magnets and to check out the diagnostics. A group of users from Aerospace Corp. upgraded their setup in user lab 4 and successfully ran some machining tests using a table-top laser. This is an important step in preparation for using the FEL.
A new computational technique is described <arXiv:0910.0992 [hep-lat]>, in which the cost of solving the linear systems in QCD calculations using anisotropic lattices can be accelerated by a factor depending on the lattice anisotropy. In testing, the condition numbers of the fermion matrix - which is a measure of how difficult it is to solve the linear system - were improved by a factor between two and three, compared to the traditional even-odd preconditioning technique. These developments will make it easier to compute observables measured in JLab experiments from first principles.
Environment, Safety, Health & Quality
1. Numbness or Weakness: sudden numbness or weakness of the face, arm or leg, especially on one side of the body.
You can determine if someone is having a stroke by asking him or her to perform these three simple things: smile, raise both arms and speak a simple sentence. Problems performing any of these tasks could indicate the person is having a stroke and must get help immediately. In order to survive a stroke and minimize long-term disability, the person must be treated without delay; otherwise, severe disability or death could occur. Even if the symptoms only last a few minutes, seek medical attention at once by calling 911 or by going to your local emergency department. For more information on strokes, visit the American Stroke Association website.
Computing and Networking Infrastructure
Maintenance Day Set for October 20, 5-10 p.m.
Performance Appraisals - Self Assessments Due Today
Access Your United Way Pledge Form Electronically
If you wish to use the traditional form, it is available for pickup at the following locations: CEBAF Center Lobby, VARC Lobby, ARC Lobby, Test Lab 2nd Floor Lobby and MCC Lobby. Detach and keep the pink carbon for your personal record and send the rest of the completed form, along with any check payments attached, to Joshua Cameron.
Change in Main Phone Number for SURA Residence Facility
JLab's Safety Numbers
91 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
Oct. 15: Safety Shoe Vendor onsite