A new study performed by scientists from Chalmers University of Technology and ETH Zürich, Switzerland has proposed a promising method to spot obscure dark matter particles through formerly uncharted atomic responses occurring in the detector material.
The latest calculations allow theorists to make comprehensive predictions about the strength and nature of interactions between electrons and dark matter, which were not possible before.
Our new research into these atomic responses reveals material properties that have until now remained hidden. They could not be investigated using any of the particles available to us today—only dark matter could reveal them.
Riccardo Catena, Associate Professor, Department at Physics, Chalmers University of Technology
For every dust cloud, star, or galaxy that is visible in space, five times more material also exists there which cannot be observed. And this material is called the dark matter. Therefore, finding ways to detect these unfamiliar particles which form such an important part of the Milky Way is a top priority in astroparticle physics.
In the universal search for dark matter, massive detectors have been constructed deep underground in an attempt to capture the particles as they bounce off atomic nuclei.
To date, these enigmatic particles have eluded detection. According to the Chalmers team, one potential explanation could be that dark matter particles are lighter than protons, and therefore do not cause the atomic nuclei to recoil—individuals can visualize a ping pong ball hitting into a bowling ball. A potential approach to resolve this issue could therefore be to change focus from nuclei to electrons, which are relatively lighter.
In their latest article, the scientists talked about how dark matter particles can network with the electrons in atoms. They proposed that the speed at which dark matter can push electrons out of atoms is governed by four autonomous atomic responses—three of which were formerly unknown. The team has computed the ways that electrons in xenon and argon atoms, utilized in today's biggest detectors, should react to dark matter.
The study results were recently reported in the Physical Review Research journal and conducted within a new partnership with Nicola Spaldin, condensed-matter physicist and her team at ETH. The researchers’ predictions can currently be tested in dark matter observatories worldwide.
We tried to remove as many access barriers as possible. The paper is published in a fully open access journal and the scientific code to compute the new atomic response functions is open source, for anyone who wants to take a look ‘under the hood’ of our paper.
Timon Emken, Postdoctoral Researcher, Dark Matter Group, Department of Physics, Chalmers University of Technology
Catena, R., et al. (2020) Atomic responses to general dark matter-electron interactions. Physical Review Research. doi.org/10.1103/PhysRevResearch.2.033195.