Shedding light on “ghost particles”
An international team of scientists, including Livermore physicists Peter Barnes, Doug Wright, and Ed Hartouni, announced that it has recorded the transformation of neutrinos from one type to another.
Neutrinos are particles with negligible mass and no electric charge yet are fundamental to the structure of the universe. Sometimes termed “ghost particles,” neutrinos are extremely difficult to detect because they rarely interact with anything. They come in three “flavors”: electron, muon, and tau. Each is related to a charged particle, which gives the corresponding neutrino its name.
The physicists have been working on the Main Injector Neutrino Oscillation Search (MINOS) Project, which was launched in 2005 to solve a 50-year-old mystery: how do neutrinos change flavors? MINOS uses two detectors, one located at the source of the neutrinos, at the Department of Energy’s Fermi National Accelerator Laboratory (Fermilab), in Batavia, Illinois, and the other located 725 kilometers away, at Soudan Underground Mine State Park in northern Minnesota.
A high-intensity beam of muon neutrinos generated at Fermilab traveled through Earth to the Soudan detector. Scientists observed that a significant fraction of these neutrinos disappeared, which indicates the muon neutrinos have changed to another kind—an effect known as neutrino oscillation. If neutrinos had no mass, the particles would not oscillate as they traverse Earth, and the MINOS detector in Soudan would have recorded many more muon neutrinos.
The findings, announced March 30, 2006, at Fermilab, will help scientists better understand how particles acquire mass, as well as neutrinos’ role in the formation of the universe and their relationship to dark matter.
Contact: Peter Barnes (925) 422-3384 (firstname.lastname@example.org).
Blue ring discovered around a giant planet
Earlier this year, scientists discovered two faint rings located well outside Uranus’s main ring system. The outer ring is centered on the orbit of the tiny moon Mab and is blue, while the other ring, which orbits between the moons Rosalind and Portia, is red.
Rings around the giant planets in our solar system—Jupiter, Saturn, Uranus, and Neptune—are typically reddish because they contain many large particles that mostly reflect longer (red) wavelengths of light. The only other known blue planetary ring
is Saturn’s E ring, which hosts the moon Enceladus.
“We suspect that both rings owe their blue color to nongravitational forces acting on dust in the rings that allow
smaller particles to survive while larger ones are recaptured by the moons,” says Livermore scientist Seran Gibbard, who is a member of the research team. The team also includes Imke de Pater of the University of California at Berkeley, Mark Showalter of the SETI Institute, and Heidi Hammel of the Space Science Institute. The team’s research appeared in the April 7, 2006, issue of Science .
The blue ring was discovered by combining near-infrared observations from the Keck Telescope in Hawaii and visible-light photos taken by the Hubble Space Telescope. After other scientists discovered two new rings around Uranus, and two new moons, Mab and Cupid, the team reported seeing the red, innermost of the two new rings, but not the outermost. The outer ring could be seen in visible light but was not observable in the near-infrared, which indicates that it must be blue.
Contact: Seran Gibbard (925) 423-0656 (email@example.com).
Pathogen informatics team contributes to SARS research
For the past six years, the pathogen informatics team in Livermore’s Biosciences Directorate has worked to find the genetic signatures of disease-causing microbes to help detect and diagnose human and animal pathogens. Recently, a Livermore-developed signature of the peculiar virus that causes severe acute respiratory syndrome (SARS) contributed to a landmark study of SARS in nonhuman primates. In the study, the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) used the Livermore signature to detect the SARS virus in the body fluids of long-tailed macaque monkeys over a period of several weeks after they were infected. The research appeared in the
May 2006 issue of PLOS Medicine.
The Livermore team began analyzing the SARS virus three years ago, after a sudden outbreak of the disease was reported
in Asia. Using a map of the virus’s genome provided by the Centers for Disease Control and Prevention (CDC), the team
of biologists, mathematicians, and computer scientists designed
an initial set of potential virus signatures in just three hours. The team then used KPATH, a Laboratory-developed computational DNA signature design system, to produce 100 potential signatures. KPATH is a fully automated DNA-based signature “pipeline” that can deliver microbial signature candidates spanning 200- to 300-plus base pairs of DNA in minutes
to hours. The CDC and USAMRIID later verified 3 of the
100 signatures in laboratory testing.
Contact: Thomas Slezak (925) 422-5746 (firstname.lastname@example.org).