Scientists use special radios to search for dark matter’s missing pieces

By
Stanford University
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A schematic representation of DMRadio-50L. The magnetic field we apply (B0) will interact with the dark matter axions to produce the axion induced current (Jeff). This in turn will induce a flux in the center of the toroid and then the currents that flow in response to that (Iret) are resonantly enhanced and measured. Credit: DMRadio Collaboration

For a long time, scientists have known that dark matter exists in our universe.

They’ve seen its effects on other things in space, but they still don’t know what it’s actually made of.

One of the candidates that might make up dark matter is a tiny particle called an axion.

Axions are not just any ordinary particles; they could help solve some big puzzles in physics. The DMRadio experiments are like detectives, specially designed to find these elusive axions.

If axions pass through a magnetic field, they can produce a very tiny electric field—so tiny it’s like trying to hear a whisper in a loud room.

To find this barely-there signal, scientists use something called a resonator, which amplifies the signal, making it easier to detect.

Imagine strumming a guitar string and then putting it on a guitar body; the sound gets louder. In a similar way, these resonators make the electric field signal stronger.

There are three DMRadio experiments:

  1. DMRadio-50L: This experiment is being built at Stanford and will use a donut-shaped magnet to produce a magnetic field. Scientists will then look for an oscillating electric current that the axions might produce.
  2. DMRadio-m3: This one uses a different kind of magnet and is being constructed at SLAC National Lab. It will look for heavier axions than DMRadio-50L.
  3. DMRadio-GUT: Still in the planning stage, this experiment aims to be super-sensitive and find even more types of axions.

Each experiment uses fancy technology like superconducting sheaths and tunable capacitors to increase their chances of detecting axions.

In simple terms, a magnetic field is applied, and if axions are around, they will produce a tiny current.

This current is picked up by special sensors that the lab makes. Because axions are so lightweight—more than 20 trillion times lighter than an electron—even a tiny signal would be a big deal.

Whether they find axions or not, these experiments will teach us more about our universe. They can also help test new types of technology.

So, as scientists continue their dark matter detective work, they’ll be listening closely for clues in places no one has ever looked before.

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