Jefferson Lab Weekly Briefs
July 7, 2010
12 GeV Upgrade
Deliveries of the new beam transport quadrupole magnets near completion, with more than 100 of the 114 ordered now on site. Closure has been reached with the vendor for the beam transport septa on annealing of the iron, and a path forward for the coil insulation for those septa magnets has been identified. During the most recent tests of the first article klystron, the klystron vendor encountered heating issues in the components that receive the power out of the klystron; straightforward corrective modifications are being made and the next test is projected for mid-July. A preliminary design review of the “box” power supplies for the beam transport dipole magnets was held. Installation of the Central Helium Liquefier system hardware continues in the new CHL building addition. The first two 12 GeV production superconducting radiofrequency cavities are expected to be delivered this month.
During the week, the CHL tripped three times, which caused about 15 hours of down time. Problems with box supplies (Hall B dipole and shunt MAC5R03) affected beam delivery for a few hours. The machine optics was optimized. The setup for the Hall A APEX Test was successfully done. Over the weekend, beam (straight ahead mode) was successfully established to the Hall C beam dump for Q-weak.
The FEL team had success in doing initial beam setup for the ultraviolet beamline and getting good beam around the full recovery path. This beam was then used for checkout of beam diagnostics and machine protection systems. The team is also making good progress in preparing the UV mirrors for installation and finishing the welding of the wiggler chamber.
In a new paper, <arxiv:1006.5444> theorists from the College of William & Mary and Hampton University (two of whom are also Theory Center associate senior staff) considered a challenging astrophysical problem of the positron excess found in the vicinity of the Milky Way galactic center, which may be related to the dynamics of elusive dark matter particles. The authors analyzed possible scenarios of positron production and concluded that the observed spatial distribution of annihilation photons cannot be due to the decay of relic dark matter; it is consistent, however, with the production of positrons in collisions between dark matter particles or possibly caused by the activity of a high-intensity radiation source located in the galactic center. Some hypotheses on positron production in collisions involving dark matter particles can be tested in the APEX experiment at JLab.
Environment, Safety, Health & Quality
The National Cancer Institute undertook a comprehensive study of possible environmental and genetic causes, including cell phones, of malignant and benign brain tumors. In the case of handheld cell phones, the study found no indication of higher brain tumor risk among persons who had used cell phones compared with those who had not used them.
The study included 782 brain tumor cases and 799 controls from three medical institutions: St. Joseph’s Hospital and Medical Center in Phoenix, Brigham and Women’s Hospital in Boston, and Western Pennsylvania Hospital in Pittsburgh. The study included brain tumor patients diagnosed with glioma (489 cases), meningioma (197 cases) or acoustic neuroma (96 cases). The control subjects were people who were admitted for a variety of non-cancerous conditions to the same hospitals as the brain tumor patients, and the control subjects were matched with the case subjects by hospital, sex, race, age and distance of residence from the hospital.
The study found that there was no evidence of increasing risk with increasing years of use or average minutes of use per day, nor did brain tumors among cell phone users tend to occur more often than expected on the side of the head on which people reported using their phone. Specifically, there was no indication of increased risk associated with use of a cell phone for one hour or more per day, for five or more years, or for cumulative use of more than 100 hours. These findings pertain to all three tumor types considered (glioma, meningioma and acoustic neuroma). For more information, visit the study Q&A on the National Cancer Institute website.
American Red Cross Blood Drive
Recharge Today at the Quark Cafe!
JLab's Safety Numbers
70 Days since Last Recordable Accident (JLab record: 331)
JLab Calendar of Events
July 19-21: JLab Science and Technology Review