Jefferson Lab Weekly Briefs September 22, 2010
Jefferson Lab Weekly Briefs
September 22, 2010
The NSF has awarded a Major Research Initiative (MRI) consortium grant for the "Development of a Complete Kaon Detection System for Hall C at 12 GeV." This grant funds the construction of an Aerogel detector, which will add Kaon detection capability to the Super High Momentum Spectrometer, the new 11 GeV spectrometer in Hall C. The consortium, led by The Catholic University of America, includes Florida International University, Mississippi State University, the University of South Carolina and as non-funded partners, the Yerevan Physics Institute and JLab.
AIP State Department Fellowship Application Deadline is Nov. 1
This week saw the move toward normal operations as Accelerator Operations staff began manning the control room 24/7. Operations for the week involved mainly hot checkout of magnets, radiofrequency and other major systems. Commissioning of 2L15 continued, and 1L07 was helium processed to improve performance. The injector was set up for 130 KeV operation, up from the previous norm of 100 KeV. Studies of photocathode emission versus beam spot position were performed in an effort to gain understanding for even higher injector gun voltages in the future. Over the weekend, it was planned to spin the beam around and set up 5-pass operations, but a newly installed master oscillator had a slightly different frequency than the old, causing the path through the machine to appear longer. After consideration, setup was punted to Monday, allowing for parity-quality beam laser studies to take advantage of the available time.
The FEL team continued characterization of the ultraviolet FEL, both the optics and the electron beam, and got extremely good performance from the laser at 400 nanometers. Staffers were able to tune up the laser to get close to 250 watts during a 1 millisecond macropulse with 6 percent duty cycle and over 400 W using 9 MegaHertz electron beam. The turn-on time was as short as five microseconds, much shorter than the one-dimensional theory predicts; the power is also much larger than the theory predicts. The gain is difficult to measure, but is in excess of 100 percent net gain. The cavity length detuning curve is as long as 8 microns. In addition, the team took and analyzed transverse profiles to figure out the emittance and match in the wiggler. The Twiss parameters looked reasonable, but the horizontal emittance looked larger than it had previously. The team plans to do quad scan measurements to get a better idea of Twiss parameters. Team members also took a great deal of data on the longitudinal distribution and have started the analysis.
Center for Theoretical and Computational Physics
The Boer-Mulders distributions describe how transversely polarized quarks are distributed in an unpolarized hadron, although at present very little is known about them. In a new paper <arXiv:1009.3423>, the Boer-Mulders antiquark distributions are extracted from unpolarized Drell-Yan data. The corresponding up and down Boer-Mulders quark distributions can be determined from data on semi-inclusive deep-inelastic scattering (SIDIS), and future SIDIS experiments at JLab will help determine their flavor decomposition.
JLab Calendar of Events
Sept. 22-24: First International Symposium on the Superconducting Science and Technology of Ingot Niobium
JLab's Safety Numbers
23 Days since Last Recordable Accident (JLab record: 331)
Environment, Safety, Health & Quality
Handheld laser pointers are considered to be harmless and safe. However, the devices can cause severe eye injury, as demonstrated by a case reported in The New England Journal of Medicine of a 15-year-old boy who ordered a green handheld laser pointer off of the Internet. The teen-ager played with his laser pointer in front of a mirror to create a "laser show," during which the laser beam hit his eyes several times. He noticed immediate blurred vision in both eyes. He underwent an ophthalmic assessment two weeks later, when he could no longer disguise his bad vision. His visual acuity was so poor in his left eye that he was only able to count fingers at a distance of 3 ft, and it was 20/50 in his right eye.
In the past, laser pointers sold to the public had a maximal output of 5 milliwatts, which is regarded as harmless, because the human eye protects itself with blink reflexes. While this laser emitted 150 mW, it was advertised as a laser pointer and looked identical to low-power pointers.
You can prevent laser injury by checking your children's laser toys. If they are unlabeled or suspect, contact the lab Laser Safety Officer for support. Check your laser pointer; it should be Class II or less. If you have a laser pointer that is greater than Class II, such as Class IIIA, contact the lab Laser Safety Officer, Dick Owen, x6381, for assistance.
Computing and Networking Infrastructure
Mac Support In the Works
Flu Vaccines Now Available
JLab's BEAMS Outreach Program Needs Your Help
Patent Your Bright Ideas at JLab
Dust Off Those Golf Clubs for the JLab 2010 Fall Golf Tournament
Einstein For Everyone Kicks Off Fall Science Series Lecture Series