Jefferson Lab Weekly Briefs
August 6, 2008
12 GeV Upgrade
The R&D task to re-measure the Higher-Order Mode (HOM) damping in the 12 GeV-style superconducting radio frequency (SRF) cavities had previously confirmed last year’s results that the damping meets the specification comfortably. Subsequently, measurements in the Vertical Test Area (VTA) have confirmed that VTA measurements can be used as a step in the overall quality assurance program to identify cavities that have marginal damping behavior prior to cryomodule assembly.
Measurements of both prototype beamline quadrupoles is underway. Initial analysis of the data found that the fields are as expected. Fine tuning of the assembly and fabrication processes will be done based on the results of the measurement.
Requests For Proposals (RFPs) were released for the 4.5 Kelvin Coldbox, klystron and SRF cavity contracts. These represent roughly half of the total contract value of the FY09 procurements for Accelerator Systems.
The repair contract for Transformer LN1 has been awarded. LN1 will be removed by a crane and shipped to the repair company. In the injector, Gun 3 was charged to 125 kilovolts (kV) for high-voltage processing, and the Gun 2 bakeout was completed. Box supply water flow and trip levels now available on EPICs and box supply maintenance continued on the dogleg magnets. The South Linac was brought to high voltage without major problems. The General Purpose Building was tied in to the electrical system, and tunnel safety training was completed.
Free-Electron Laser (FEL)
The FEL staff is making good progress with installing beamline for the ultraviolet (UV) system. On the gun test stand, a new cathode was made after mildly baking the system to reduce water; a quantum efficiency of 16 percent was achieved. The 3rd Optical Transfer System Turning Mirror Cassette for the infrared (IR) line was hung on the ceiling, and the FEL gun is nearing final assembly.
In a Theory Center paper (arXiv:0807.0944v1 [hep-ph]) last month, the up and down quark contributions to the proton magnetic form factor at finite momentum transfer were determined by applying chiral corrections to quenched lattice data. Combined with the experimental values of the proton and neutron magnetic form factors, a relatively accurate value for the strange magnetic form factor was obtained, i.e. GsM= -0.034 ± 0.021 in units of the nuclear magneton. This result is in excellent agreement with the recent determination of GsM at Mainz.
JLab's Safety Numbers
296 Days since Last Recordable Accident (JLab record: 319)
JLab Calendar of Events
Aug. 12-14 Occupational Medicine Cholesterol Screenings
Environment, Safety, Health & Quality
A rattlesnake was recently sighted during a contractor walkthrough on the north end of the property bordering Canon Boulevard. This section of the site is currently in a natural state, but it will be used during construction of the Hall D complex. There were no interactions with the snake and no one was injured.
It's always a good idea to wear boots and long pants in wooded areas. Also, if you sight a snake, give it a wide berth. Eighty percent of snake bites occur when people are trying to kill the animal, so the most prudent action is to distance yourself from the threat right away.
If you are bitten, the best course of action is to get to an emergency room as soon as possible; remain calm and keep the injured area lower than the heart. If possible, information on the snake's marking and appearance should be noted.
Computing and Networking Infrastructure (CNI)
The CNI group is planning a systems maintenance period from 5-10 p.m. on Tuesday, Aug. 12. Currently, the only planned outage is a configuration outage to the bbftp server, a scientific computing parallel ftp server.
Other maintenance should be non-intrusive, however, new security patches will be pushed out to all Linux and Windows systems. If you work on one of these systems, please log out of all desktop computers at the end of your workday Aug. 12, but leave the systems powered on overnight so that the patches can be installed. If you experience difficulties with your computer, reboot to see if that fixes the problem before calling the Help Desk (x7155) for assistance.
Cholesterol Screenings Offered Aug. 12-14
Instructions for All International Visitors to Jefferson Lab
Christoph Leemann Retirement Reception
Property Management Reminder: Removing Property
An Employee Property Pass or loan agreement with another institution is required from the JLab Property Office before property is removed from the lab. While offsite, the safe keeping of the property is the responsibility of the employee or institution having temporary custody. For more information, consult the JLab Property Manual.