Jefferson Lab Weekly Briefs
May 21, 2008
12 GeV Upgrade
The R&D task to extend the earlier measurements of the Higher-Order Mode (HOM) damping in the 12 GeV-style superconducting radio frequency (SRF) cavities is proceeding. Re-assembly of the cavities into the Horizontal Testbed (HTB) is almost complete, and cooldown is planned for early next week with measurements in the Cryomodule Test Facility to follow.
Sample laminations for the prototype Beam Transport quadrupoles have been received from the new vendor. They were inspected and found to meet specifications. The vendor has been instructed to proceed with manufacturing the completion of the order.
The Power System underwent two design status and safety reviews last week; RF and Magnet Power systems were reviewed separately. Both of the review panels found that the work was going well and is on track for completion consistent with the 12 GeV Project's needs.
Hall A successfully completed (Electroproduction of Pi-Zero near Threshold) on May 8. After a short changeover period, experiment E08-007 (Measurement of the Proton Elastic Form Factor Ratio at Low Q2) started on May 15 and has been making good progress.
In Hall B, experiments in the g12 run period continued data taking. About 15 billion triggers have been collected to date. Parallel to CLAS data taking, a test of the CLAS12 pre-shower prototype is in progress using the Hall B pair spectrometer. This is the first beam test of a CLAS12 detector prototype.
The lifter mechanism for the Hall C Q-weak target has been delivered. The parts for this target, which will be the highest power cryotarget in the world, are starting to be assembled in the Test Lab.
This period saw a continuation of quality continuous wave (CW) beam delivery to the experimental halls. While Hall A was in the midst of a configuration change at the start of the week, the hall was successfully brought back online Thursday, and a new experiment is underway. The only significant interruptions in beam delivery were several weather-related power glitches. The week ended with the accelerator continuing to deliver beam, with the summer scheduled accelerator down (SAD) rapidly approaching.
Free-Electron Laser (FEL)
The FEL gun has been moved out of the FEL building so it can be rebuilt and re-assembled; the ceramic stack has been cut apart for welding in a new ceramic. FEL staff members are awaiting quotes for a protective ceramic sleeve to install inside the existing ceramic. FEL staff verified that one of the quadrupoles, powered by the same trim rack used in the accelerator, meets the very stringent amplifier and UV magnet specifications. A plan has been put together to power multiple magnets using the trim rack in the magnet test area and verify that several magnets can be put through their hysteresis loops at the same time without affecting the magnet performance. A major step was taken in upgrading the optical transport system. All the “OTS-Lite” vessels have been removed, and the areas are being prepared for installation of the final OTS mirror vessels. The control system for the transport vessels has also been specified and ordered.
Recent measurements of the Sivers effect with detected pions and kaons in the final state at HERMES suggest non-negligible contributions from sea quarks to the Sivers function around x=0.15. In a new Theory Center paper, arXiv:0805.2137 [hep-ph], fits to HERMES and COMPASS data are presented, which take sea quark effects into account. Although the overall description is statistically satisfactory, a discrepancy between the pion and kaon Sivers effect remains, which new data from CLAS12 and COMPASS should help to clarify.
The power systems portion (RF System and Magnet Power) of the 12 GeV Upgrade have successfully completed Status & Safety reviews. This is in preparation for 12 GeV Independent Project Review in July.
JLab's Safety Numbers
245 Days since Last Recordable Accident (JLab record: 319)
Environment, Safety, Health & Quality
Recently, a Portsmouth Gas Diffusion Plant employee was injured when his finger was struck by a falling gas regulator. The employee disconnected the nitrogen regulator from the empty nitrogen bottle and placed the regulator assembly on top of the nitrogen storage cabinet. As the employee was removing the cylinder, the top of the cylinder became tangled in the regulator hose and wiring. The regulator fell from the top of the cabinet and pinned the employee’s left ring finger between the regulator assembly and the cabinet door frame, resulting in a fracture. The employee was wearing proper personal protective equipment (including gloves) for the job being performed. The regulator assembly weighed nearly 30 pounds and fell about two feet.
This activity is performed by trained staff on a frequent basis. This was an “error-likely” situation due to the work environment in the nitrogen cabinet. The nitrogen cabinet is very narrow and has limited work space in the cabinet. This nitrogen cabinet had been previously equipped with a chain mechanism to support the regulator when changing bottles. However, the chain support on the regulator had been removed. Therefore, when the employee removed the regulator assembly, he did not have any way to support the regulator assembly, and he placed it on the top of the cabinet while changing the empty nitrogen cylinder to get it out of his way. Being focused on the task of changing the empty nitrogen bottle, the employee did not recognize the potential hazard involved if the regulator were to fall.
Lessons to be learned from this accident:
Systems designed to prevent accidents must have configuration control. Do not modify a system in such a way that it disables safety features. Decisions that result in a unsafe act or injury are usually part of a chain of decisions that, taken together, increase that likelihood of an accident. Break that chain! There are no unimportant decisions when it comes to safety.
Computing and Networking Infrastructure
An e-mail received by hundreds of JLab computer account holders this afternoon was a Dept. of Energy cybersecurity test. The e-mail with the subject line "HSPD-12 Identification Briefing," was an no-notice authorized test. So, if you did click on the html link in the e-mail or if you responded, nothing is wrong with your computer.
JLab's Computing and Network Infrastructure Group reports that within two minutes of the first e-mail being received by JLab computer account holders, individuals were calling the IT Division to report the suspicious e-mail.
If you have any questions regarding suspicious e-mails, contact JLab's HelpDesk (firstname.lastname@example.org) or call 757-269-7155.
Safety Shoe Truck Fills Approved Orders Thursday, May 22
TIAA-CREF June Retirement Counseling Session
Scavengers steal from local college fleet vehicles
Kris Burrows, JLab's Security officer, reminds everyone to:
JLab Calendar of Events
May 19-23: The 4th Electron Ion Collider Workshop