Ambitious new dark matter-hunting experiment delivers 1st results

illustration showing a conical silver object against a gray and black background
A diagram of the BREAD experiment against a simulation of dark matter. (Image credit: BREAD Collaboration /Ralf Kaehler/SLAC National Accelerator Laboratory)

A new experiment designed to search the cosmos for its most mysterious "stuff," dark matter, has delivered its first results. 

While the Broadband Reflector Experiment for Axion Detection (BREAD) developed by the University of Chicago and the U.S. Department of Energy's Fermilab hasn't turned up dark matter particles just yet, the new results place a tighter constraint on the type of characteristics scientists can expect such particles to have. The BREAD experiment itself also served up an exciting new recipe that could be used in the hunt for dark matter — a relatively inexpensive one that doesn't take up a vast amount of space. 

BREAD takes a "broadband" approach to search for hypothetical dark matter particles called "axions" and associated "dark photons" across a larger set of possibilities than other experiments, albeit with slightly less precision.

"If you think about it like a radio, the search for dark matter is like tuning the dial to search for one particular radio station, except there are a million frequencies to check through," University of Chicago scientist and BREAD project co-leader David Miller said in a statement. "Our method is like doing a scan of 100,000 radio stations, rather than a few very thoroughly."

Related: What is dark matter?

A small experiment to tackle a big problem

Dark matter represents a huge problem for scientists because, despite the fact it makes up around 85% of the matter in the universe and its influence prevents galaxies from flying apart as they spin, we have little idea what it is made of.

That is in part because dark matter is effectively invisible; it doesn't seem to interact with light, neither emitting nor reflecting standard photons. That lack of electromagnetic interaction suggests that dark matter isn't composed of the protons, neutrons and electrons that comprise "normal matter" objects like stars, planets, moons, our bodies and the cat next door.

Though our telescopes can't detect dark matter directly, the stuff does affect stars, galaxies, and even light via its interactions with gravity. So astronomers can tell that something is there — they just don't know what it is. Knowing what to look for and exactly where to look is a different matter.

"We’re very confident that something is there, but there are many, many forms it could take," said Miller.

This confusion has sent scientists on the hunt for different particles with strange properties that could comprise dark matter. One such candidate is the axion, a hypothetical particle with an extremely small mass. Should axions exist, they may interact with a so-called dark photon just as everyday matter interacts with "ordinary" photons. This interaction could occasionally prompt the creation of a visible photon under certain circumstances. 

The components of the BREAD dark matter experiment (Image credit: BREAD Collaboration)

BREAD is a coaxial dish antenna in the shape of a curved metal tube that can fit on a tabletop. The experiment is designed to catch photons and funnel them to a sensor at one end to search for a subset of possible axions.

The full-scale BREAD experiment will see the equipment sit within a strong magnetic field, which the team says will increase the chances of the conversion of axons to photons. As a proof of principle, the team conducted a BREAD experiment minus the magnets needed to generate this field.

The proto-BREAD experiment ran at the University of Chicago for a month and delivered some interesting data, whetting the team's appetite for the full-scale experiment. The test results showed that BREAD was highly sensitive in the range of frequencies that the team had designed it to probe. 

"This is just the first step in a series of exciting experiments we are planning," BREAD co-leader and Fermilab researcher Andrew Sonnenschein said. "We have many ideas for improving the sensitivity of our axion search."

The test also demonstrated that particle physics can be done on a tabletop as well as in huge particle accelerators like the Large Hadron Collider (LHC), which runs for 17 miles (27 kilometers) deep under the border between France and Switzerland.

"This result is a milestone for our concept, demonstrating for the first time the power of our approach," said Stefan Knirck, the Fermilab postdoctoral scholar who led the development and construction of BREAD. "It is great to do this kind of creative tabletop-scale science, where a small team can do everything from building the experiment to data analysis but still have a great impact on modern particle physics."

The next stage of the BREAD experiment will see the apparatus transported to the magnet facility at Argonne National Laboratory. Additionally, facilities like SLAC National Accelerator Laboratory, MIT, Caltech, and NASA's Jet Propulsion Laboratory are working on research and development with the University of Chicago and Fermilab for future recipes of the BREAD experiment.

"There are still so many open questions in science and an enormous space for creative new ideas for tackling those questions," Miller concluded. "I think this is a real hallmark example of those kinds of creative ideas — in this case, impactful, collaborative partnerships between smaller-scale science at universities and larger-scale science at national laboratories."

The team's research is detailed in a paper published late last month in the journal Physical Review Letters.

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Robert Lea
Senior Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

  • philbundy
    Admin said:
    The new BREAD experiment, which was designed to search the cosmos for mysterious dark matter, has returned its first results.

    Ambitious new dark matter-hunting experiment delivers 1st results : Read more
    Dark matter is not matter at all it is magnetism and electromagnetic waves are invisible to us. It can be nothing else; I realize pretending to look for it pays the bills, so carry on.
  • danR
    philbundy said:
    Dark matter is not matter at all it is magnetism and electromagnetic waves are invisible to us. It can be nothing else; I realize pretending to look for it pays the bills, so carry on.
    Photons aren't light at all it is electromagnetic waves in the aether it can be nothing else I realize pretending to look for them pays the bills so carry on like this run-on sentence.
  • Mergatroid
    philbundy said:
    Dark matter is not matter at all it is magnetism and electromagnetic waves are invisible to us. It can be nothing else; I realize pretending to look for it pays the bills, so carry on.
    It has been proven that dark matter has gravity. A lot of it. How do electromagnetic waves have gravity? In fact, if they had gravity it would have been proven a longtime ago. If electromagnetic waves had gravity we would see it in colliders and fusion reactors.
    Tell us another story.
  • Papaspud
    Whenever I see the terms- dark matter, or dark energy as the explanation for something or another that they have no clue about, and are just wildly guessing...I just go back to my roots and translate= Magic!
  • Torbjorn Larsson
    Dark matter (as well as dark energy) - or readily visible electromagnetic radiation light - is not personal opinion "guess it's magic" but well observed phenomena with lots of clues. For instance while both light and dark matter "has gravity" only the latter has intrinsic mass. That is why we call it particulate "matter".

    The axion would have too small mass to be the best fit to cosmological observations, but it is possible. A more exciting search has just opened up since estimates show that neutron stars may work as general dark matter detectors:

    It was recently pointed out that old, isolated, NSs in the Solar neighborhood could be heated by DM capture , leading to a temperature increase of ∼ 2000 K. At ages greater than ∼ 10 Myr, isolated NSs are expected to cool to temperatures below this, provided they are not reheated by accretion of standard matter or by internal heating mechanisms . Asa result, the observation of a local NS with a temperature O(1000 K) could provide stringent constraints on DM interactions. Importantly, NS temperatures in this range would result in near-infrared emission, potentially detectable by future telescopes.
  • Unclear Engineer
    At this point, both "dark matter" and "dark energy" are really only theoretical place holders in our theories, needed to make the theories fit the observations. Theorists have been free to assume that each does exactly what is needed to make the fits, without doing anything else that would mess-up the fits.

    Experiments to detect, or if not detect, limit the range of potential parameters for dark matter and dark energy candidates have so far just made the limits somewhat tighter, without any real detections.

    All we can really say at t his point is that "something" is making our observations differ from our expectations based on the physics that we understand, and use the "dark" names for those "somethings", until we actually find something - or realize that we have been missing something important in the theories.

    At this point, I think we are going to need a bigger telescope.
  • Manix
    What any of this proves is that we don't understand the univers (and the likes of gravity) as well as we think we do. The fact all these experiments come up empty handed while looking for Dark Matter, says a lot. As Occams Razor goes..
  • Evil Red Smurf
    There are many theories and nobody knows the truth yet. A theory I like is the following:
    "Gravity in space-time is like an elastic band, and a star is like a weight hung from the elastic band - The greater the weight that is hung the more stretched the elastic band. When the weight is removed the elastic band returned to its original length and shape. However if the weight hung from the elastic bank is insufficient to snap it, but greater than the elasticity limit of the elastic, then when the weight is removed the elastic does not return to its original shape. Instead it is left with a ripple. The stretch on the elastic is like the gravitational effect of the star on space-time, but with Black Holes this is different, they stretch space-time, and if space-time has an elasticity limit then it may not return to its original 'shape'. Instead space-time is left with a ripple. What is that ripple? It's a fluctuation in space-time that behaves as though there is matter present, but without there being matter present - therefore: no visible matter, no reflected particles, in fact nothing there. But still bending light from distant stars as though there is a body present."
  • Hardcrunchyscience
    Admin said:
    The new BREAD experiment, which was designed to search the cosmos for mysterious dark matter, has returned its first results.

    Ambitious new dark matter-hunting experiment delivers 1st results : Read more
    Yes, I read the paper. One implication is that a (literally) tabletop experiment can succeed where a multibillion dollar behemoth (LHC) with methods used for decades has failed. I've seen this before - cold fusion. Don't bet any money on it.
  • JCD
    "Dark Matter" adds another onion layer of unknowing to what I already don't know. I admire those who are determined to investigate such questions. I am not sure I'm up to that level of challenge.