When it goes online, the MAGIS-100 experiment at the Department of Energy’s Fermi National Accelerator Laboratory and its successors will explore the nature of gravitational waves and search for certain kinds of wavelike dark matter. But first, researchers need to figure out something pretty basic: how to get good photographs of the clouds of atoms at the heart of their experiment.
August 19, 2022
When it goes online, the MAGIS-100 experiment at the Department of Energy’s Fermi National Accelerator Laboratory and its successors will explore the nature of gravitational waves and search for certain kinds of wavelike dark matter. But first, researchers need to figure out something pretty basic: how to get good photographs of the clouds of atoms at the heart of their experiment.
Researchers at the Department of Energy’s SLAC National Accelerator Laboratory realized that task would be perhaps the ultimate exercise in ultra-low light photography.
But a SLAC team that included Stanford graduate students Sanha Cheong and Murtaza Safdari, SLAC Professor Ariel Schwartzman, and SLAC scientists Michael Kagan, Sean Gasiorowski, Maxime Vandegar, and Joseph Frish found a simple way to do it: mirrors. By arranging mirrors in a dome-like configuration around an object, they can reflect more light towards the camera and image multiple sides of an object simultaneously.
And, the team reports in the Journal of Instrumentation, there’s an additional benefit. Because the camera now gathers views of an object taken from many different angles, the system is an example of “light-field imaging”, which captures not just the intensity of light but also which direction light rays travel. As a result, the mirror system can help researchers build a three-dimensional model of an object, such as an atom cloud.
“We’re advancing the imaging in experiments like MAGIS-100 to the newest imaging paradigm with this system,” Safdari said.
An unusual photographic challenge
The 100-meter-long Matter-wave Atomic Gradiometer Interferometric Sensor, or MAGIS-100, is a new kind of experiment being installed in a vertical shaft at DOE’s Fermi National Accelerator Laboratory. Known as an atom interferometer, it will exploit quantum phenomena to detect passing waves of ultralight dark matter and free-falling strontium atoms.
Experimenters will release clouds of strontium atoms in a vacuum tube that runs the length of the shaft, and then shine laser light on the free-falling clouds. Each strontium atom acts like a wave, and the laser light sends each of these atomic waves into a superposition of quantum states, one of which continues on its original path while the other one is kicked much higher up.
