Cal State East Bay Physics Department Helps Spearhead Global Effort to Understand Dark Matter
Associate Physics Professor Derek F. Jackson Kimball, Ph.D
- March 12, 2015
The Department of Physics at California State University, East Bay is participating in a unique international experiment — the Global Network of Optical Magnetometers for Exotic physics (GNOME) — to search for a theoretical object known as a "domain wall," a fracture or boundary in space. If they exist, domain walls could help physicists understand the nature of dark matter.
Little is known about the nature of dark matter, invisible material in space that does not emit or absorb light but is detectable through its gravitational pull, which affects the motion of galaxies and galactic clusters. Measurements of these gravitational effects of dark matter show that there is five times more dark matter than ordinary matter (material made of atoms: stars, planets, gas clouds, etc.) in the universe.
If dark matter takes the form of domain walls, crossing such a wall would exert a tiny force on spinning atoms, similar to the force of a magnetic field. To search for a domain wall, the GNOME experiment will use five atomic magnetometers (sensors) strategically located around the world. These sensors can detect magnetic fields billions of times smaller than the magnetic field of Earth. If the planet passes through a domain wall made of dark matter, the atoms spinning inside the device will begin to wobble, and the sensors will detect the moment when this wobble occurs.
Derek F. Jackson Kimball, Ph.D, associate professor of physics at CSUEB and one of the physicists spearheading the project, says that five sensors are necessary to get an accurate reading. "If we were to use one sensor, we couldn’t be sure that what we were seeing wasn’t caused by other outside factors, such as magnetic field noise or vibrations or other interference. But using five sensors synced together by GPS lets us filter out random, uncorrelated noise," Jackson Kimball said. "If we see a similar result at different times on the sensors around the world, and the timing of the events matches what we expect from Earth passing through a dark matter domain wall, then we know we’ve got a legitimate reading. Detection of events with four of the sensors predicts when the fifth event will occur. If a fifth event matches the prediction from the first four, it could mean we’ve moved through a domain wall and we’ll have a huge clue as to what dark matter might be," he said.
Prototypes for the sensors are currently being built, and at least three of them, including CSUEB’s, are scheduled to go online this summer. In addition to the sensor on CSUEB’s Hayward campus, three others will be located in Poland, Germany, and South Korea. The fifth site has yet to be determined, but possible sites include Ohio, India, Israel, and Latvia.
Jackson Kimball said the GNOME experiment presents a unique opportunity for CSUEB undergraduate students. "Our prototype sensor at East Bay is being built by undergraduates and that’s very unusual," he said. "Normally this type of work in the physics community is reserved for graduate students or postdoctoral researchers, but since the physics department here at East Bay doesn’t have a graduate program, it allows our undergrads to experience actual field research from the ground up. There aren’t that many universities where that occurs."
Jackson Kimball added that the GNOME project also teaches students the value of teamwork and connects them with colleagues around the world. "The great thing about this project is that a publicly funded university like Cal State East Bay is able to engage in international collaboration with other physicists," Jackson Kimball said. "A career in physics doesn’t take place in a vacuum. It requires working in tandem with others in your field. This too is an important lesson for our students."