Over the last few decades, there has been a lot of effort to look for new fundamental particles with a similar mass to a proton. Since scientists fail to find one, they turn to other well-motivated candidates in axions and dark photons.
Search for Mysterious Substance
It is estimated that 80% of the matter in the universe is "dark matter," an elusive substance that does not release, absorb, or reflect light. This prevents it from being detected directly using conventional approaches. This component of the universe is only discerned from its gravitational attraction.
The existence of dark matter is currently well-documented, but astrophysicists still try to devise effective techniques to detect this substance and confirm its composition. While they know that there is a form of matter around us that does not radiate and interacts only very weakly, they do not know what it is made from.
New Approach for Searching Dark Matter
In a recent study, a group of researchers presented a new method of searching for light-dark matter candidates using a method proposed by the Broadband Reflector Experiment for Axion Detection (BREAD) Collaboration. This project is run by scientists at the University of Chicago and the Fermi Accelerator Laboratory.
The new strategy involves using a coaxial dish antenna to pick up signals associated with axions and dark photons. Their research findings are described in the paper "First Results from a Broadband Search for Dark Photon Dark Matter in the 44 to 52μeV Range with a Coaxial Dish Antenna."
Axions and dark photons are assumed to be about one trillion times lighter than photons, so detecting them would require very different technologies. Although the BREAD collaboration is still in its infancy, the technology it introduced was designed to search for these lighter particles.
Led by Stefan Knirck, the research team aims to start testing this technology in an initial small-scale experiment. It is based on the idea that if an axion or dark photon, dark matter, exists, it can convert to light particles on a metallic wall. These photons will be emitted perpendicular to the wall.
In their first experiment, the researchers focused on detecting light in the microwave regime. Although they did not pick up any relevant signal, their setup was found to be around 10,000 times more sensitive to the dark photon signal power within a mass range of 44 - 52 µeV than previously proposed techniques.
To unlock the sensitivity of their experiment to axion-like dark matter, the scientists are currently running it in a 4T magnet at Argonne National Laboratory. The team hopes their new method will enable them to explore the most well-motivated axion models, eventually leading to their detection.
Knirck and colleagues are also building more prototypes that combine the concept with other cutting-edge quantum technology to be sensitive to single light particles at the focus. At Fermilan, the team expects to receive an even more powerful magnet, which will make their experiments much more sensitive. In the future, they aim to conduct a large-scale experimental program with a setup on the ~10m scale inside a giant magnet, allowing them to investigate the best-motivated models.
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