Jefferson Lab Weekly Briefs April 23, 2008

Jefferson Lab Weekly Briefs

April 23, 2008

12 GeV Upgrade

A review of the planned Silicon Vertex Tracker (SVT) Detector for the Hall B CLAS12 spectrometer was held on April 2. Since this is a new detector technique for JLab, three outside experts on the design, construction and operation of these detectors and associated electronics formed the review committee. The Hall B team of scientists and engineers received very valuable technical input and three recommendations for further work. On April 15-17, a design and safety review of the seven superconducting magnets planned for the Halls B and C spectrometers was held. Key collaborators from Michigan State University (Hall C) and from the Efremov Institute (Hall B) attended the review to present their work alongside the JLab team. The review committee gave very high marks for the significant progress since the 2006 magnet review, and lively technical discussions provided valuable feedback to fold into further work to complete the reference designs of these magnets.



In Hall C, E04-108, the measurement of GEp/GMp continues to take data at its highest Q2 point of 8.8 (GeV/c)2. At the beginning of April, tests of the detectors to be used for SANE (Spin Asymmetries on the Nucleon Experiment) were made under beam conditions similar to those expected for the experiment. Portions of all three SANE detectors (Fiber tracker, Gas Cerenkov and Lucite hodoscope) were instrumented and placed in front of BigCal to make a first test of BETA, the Big Electron Telescope Array. The SANE experiment is scheduled to run this October.


The accelerator is settling in well for the current scheduled run to the halls. Total beam hours distributed between the three experimental halls increased to 343 hours for this reporting period. The increase in accelerator beam delivery hours is a reflection of the well-managed effort being put forth to optimize the RF. Also many thanks go to expert and timely support from numerous staff members of various equipment maintenance groups.



Free-Electron Laser (FEL)

The gun test stand (GTS) effort began the long task of fully characterizing the performance at high charge and comparing it with theory. The first of such studies involved verification of the temporal behavior of the drive laser pulse.


Location Change for Ultimate Frisbee at JLab
Looking for fun, excitement and a great way to work off your stress during lunch? Come out and play Ultimate Frisbee on Tuesdays and Thursdays, noon-1 p.m. The group plays behind CEBAF Center near the volleyball court. Beginners and experienced players welcome. For more information on JLab's Ultimate Frisbee group and a map of the playing field, visit the Jefferson Activities Group webpage. For specific questions, contact Ross Bailes at or x7623.

Safety Shoe Truck Fills Approved Orders Thursday, April 24
The Safety Shoe Truck will be at the ARC loading dock on Thursday, April 24, from 2-4 p.m. to fill approved Purchase Requisitions. Only those with approved requisitions can get shoes. Get PRs in as soon as possible through Webstock – click on Veteran Shoes. For assistance, contact Estelle Seeley, x7238, or Renee Carter, x7954.


Environment, Safety, Health & Quality

Lightning can occur at any time of the year, but it's much more frequent during the warmer months. Here are some simple tips from the National Lightning Safety Institute for lightning safety:

  • Plan your safety measures and escape route in advance. When you first see or hear lightning, get into a fully enclosed building or a vehicle with the windows rolled up. Lightning often precedes rain, so don't wait for the rain to begin before stopping your outdoor activities.
  • If outdoors, make sure that you avoid water, high ground and open spaces. Avoid all metal objects, including electric wires, fences, machinery, power tools and motors. 
  • If indoors, avoid water. Make sure that you stay away from doors and windows. Do not use the telephone; a cell phone may be used. Turn off, unplug and stay away from appliances, computers, power tools and televisions.
  • Do not resume outdoor activities until at least 30 minutes after the last observed lightning or thunder.

More lightning and other severe weather safety information is available in Chapter 3510-T4, Severe Weather Procedures in the JLab EH&S Manual.

DOE Five-Wheeled Dolly Use Lesson Learned
A recent DOE-wide lesson learned on a five-wheeled dolly "near miss" event at the DOE's Hanford facility is applicable to JLab activities. The dolly is very similar to the caster-wheeled dollys on upright cryogenic dewars in wide use at JLab. Shipping containers (~400 pounds each) were being moved onto a process truck for transfer. While moving one of the containers from the loading dock into the truck, one of the dolly wheels caught in the gap between the loading dock's lift leveler and the truck bed. A container tipped forward, landing on its side in the truck bed. Loss of control during heavy material movement can damage valuable equipment and injure personnel. If the truck had been backed closer to the dock the gap would have been eliminated.

The lift levelers slight downward curve to the truck bed caused two of the five dolly wheels to lose contact with the surface, creating instability that contributed to the event. Workers indicated that once the dolly wheel caught in the gap, the container slid within the dolly ring prior to tipping over. The event evaluation concluded that the geometry of the truck and the dock lift leveler was the major factor in this event. Event lessons learned included:

  • Use the buddy system when moving large, heavy containers on five-wheeled dollies over rough or pronounced transitional areas.
  • Ensure rough transition areas are minimized before moving across them. Inspect these potentially hazardous spots and attempt to mitigate them by making adjustments.
  • Be aware of your work environment, especially when conditions or configurations may have changed. Take the time to inspect for and make adjust to potential hazards, as appropriate.
  • Supervisors should reinforce to their workers the need to maintain constant awareness of hazards.
  • Coworkers should check that they are safe from hazards and continuously survey the situation for changing conditions.

Computing and Networking Infrastructure (CNI)

Attention JLab Wireless Network Users
The credentials used to create secure connections on the jlab_secure wireless network will expire on May 15. Prior to that time, all secure_wireless users will need to update their systems with new credentials files. If this update is not made, access to jlab_secure will stop working on May 15. The procedure for performing the update and more information can be found on the Computer Center website. Note that this change does not affect the guest wireless that relies on WEP keys that are manually updated every few months.


JLab's Safety Numbers

217 Days since Last Recordable Accident (JLab record: 319)
536 Days since Last Lost Workday Accident (JLab record: 536)

JLab Calendar of Events

April 24: Safety Shoe Truck onsite
May 5-9: Spring Cleanup Week
May 8-9: DOE Network Security Monitoring Technical Summit
May 14: JLab Run-A-Round
May 19-23: The 4th Electron Ion Collider Workshop
May 26: Memorial Day Holiday (JLab closed)



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