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First results from BREAD experiment demonstrate a new approach to searching for dark matter

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First results from BREAD experiment demonstrate a new approach to searching for dark matter


One of the great mysteries of modern science is dark matter. We know dark matter exists thanks to its effects on other objects in the cosmos, but we have never been able to directly see it. And it’s no minor thing — currently, scientists think it makes up about 85% of all the mass in the universe.

A new experiment by a collaboration led by the University of Chicago and Fermi National Accelerator Laboratory, known as the Broadband Reflector Experiment for Axion Detection or BREAD, has released its first results in the search for dark matter in a study published in Physical Review Letters. Though they did not find dark matter, they narrowed the constraints for where it might be and demonstrated a unique approach that may speed up the search for the mysterious substance, at relatively little space and cost.

“We’re very excited about what we’ve been able to do so far,” said UChicago Assoc. Prof. David Miller, co-leader for the experiment alongside Fermilab’s Andrew Sonnenschein, who originally developed the concept for the experiment. “There are lots of practical advantages to this design, and we’ve already shown the best sensitivity to date in this 11-12 gigahertz frequency.”

“This result is a milestone for our concept, demonstrating for the first time the power of our approach,” said Fermilab postdoctoral scholar and study lead author Stefan Knirck, who spearheaded the construction and operation of the detector. “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.”

‘Something is there’

When we look around the universe, we can see that some kind of substance is exerting enough gravity to pull on stars and galaxies and passing light, but no telescope or device has ever directly picked up the source — hence the name ‘dark matter.’

However, because no one has ever seen dark matter, we don’t even know exactly what it might look like or even precisely where to look for it. “We’re very confident that something is there, but there are many, many forms it could take,” said Miller.

Scientists have mapped out several of the most likely options for places and forms to look. Typically, the approach has been to build detectors to very thoroughly search one specific area (in this case, set of frequencies) in order to rule it out.

But a team of scientists explored a different approach. Their design is “broadband,” meaning that it can search a larger set of possibilities, 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,” said Miller. “Our method is like doing a scan of 100,000 radio stations, rather than a few very thoroughly.”

A proof of concept

The BREAD detector searches for a specific subset of possibilities. It’s built to look for dark matter in the form of what are known as “axions” or “dark photons” — particles with extremely small masses that could be converted into a visible photon under the right circumstances.

Fermilab’s Stefan Knirck with components of the BREAD detector.

Thus, BREAD consists of a metal tube containing a curved surface that catches and funnels potential photons to a sensor at one end. The entire thing is small enough to fit your arms around, which is unusual for these types of experiments.

In the full-scale version, BREAD will be settled inside a magnet to generate a strong magnetic field, which ups the chances of converting dark matter particles into photons.

For the proof of principle, however, the team ran the experiment sans magnets. The collaboration ran the prototype device at UChicago for about a month and analyzed the data.

The results are very promising, showing very high sensitivity in the chosen frequency, the scientists said.

Since the results published in Physical Review Letters were accepted, BREAD has been moved inside a repurposed MRI magnet at Argonne National Laboratory and is taking more data. Its eventual home, at Fermi National Accelerator Laboratory, will use an even stronger magnet.

“This is just the first step in a series of exciting experiments we are planning,” said Sonnenschein. “We have many ideas for improving the sensitivity of our axion search.”

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

The BREAD instrument was built at Fermilab as part of the laboratory’s detector R&D program and then operated at UChicago, where the data for this study were collected. UChicago Ph.D graduate student Gabe Hoshino led the operation of the detector, along with undergraduate students Alex Lapuente and Mira Littmann.

Argonne National Laboratory maintains an important magnet facility that will be used for the next stage of the BREAD physics program. Other institutions, including SLAC National Accelerator Laboratory, Lawrence Livermore National Laboratory, Illinois Institute of Technology, MIT, the Jet Propulsion Laboratory, the University of Washington, Caltech, and the University of Illinois at Urbana-Champaign, are working with UChicago and Fermilab on R&D for future versions of the experiment.

Funding: U.S. Department of Energy Office of Science, University of Chicago Joint Task Force Initiative, Cambridge Junior Research Fellowship, Kavli Institute for Particle Astrophysics and Cosmology Porat Fellowship.



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Researchers create artificial cells that act like living cells

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Researchers create artificial cells that act like living cells


In a new study published in Nature Chemistry, UNC-Chapel Hill researcher Ronit Freeman and her colleagues describe the steps they took to manipulate DNA and proteins — essential building blocks of life — to create cells that look and act like cells from the body. This accomplishment, a first in the field, has implications for efforts in regenerative medicine, drug delivery systems, and diagnostic tools.

“With this discovery, we can think of engineering fabrics or tissues that can be sensitive to changes in their environment and behave in dynamic ways,” says Freeman, whose lab is in the Applied Physical Sciences Department of the UNC College of Arts and Sciences.

Cells and tissues are made of proteins that come together to perform tasks and make structures. Proteins are essential for forming the framework of a cell, called the cytoskeleton. Without it, cells wouldn’t be able to function. The cytoskeleton allows cells to be flexible, both in shape and in response to their environment.

Without using natural proteins, the Freeman Lab built cells with functional cytoskeletons that can change shape and react to their surroundings. To do this, they used a new programmable peptide-DNA technology that directs peptides, the building blocks of proteins, and repurposed genetic material to work together to form a cytoskeleton.

“DNA does not normally appear in a cytoskeleton,” Freeman says. “We reprogrammed sequences of DNA so that it acts as an architectural material, binding the peptides together. Once this programmed material was placed in a droplet of water, the structures took shape.”

The ability to program DNA in this way means scientists can create cells to serve specific functions and even fine-tune a cell’s response to external stressors. While living cells are more complex than the synthetic ones created by the Freeman Lab, they are also more unpredictable and more susceptible to hostile environments, like severe temperatures.

“The synthetic cells were stable even at 122 degrees Fahrenheit, opening up the possibility of manufacturing cells with extraordinary capabilities in environments normally unsuitable to human life,” Freeman says.

Instead of creating materials that are made to last, Freeman says their materials are made to task — perform a specific function and then modify themselves to serve a new function. Their application can be customized by adding different peptide or DNA designs to program cells in materials like fabrics or tissues. These new materials can integrate with other synthetic cell technologies, all with potential applications that could revolutionize fields like biotechnology and medicine.

“This research helps us understand what makes life,” Freeman says. “This synthetic cell technology will not just enable us to reproduce what nature does, but also make materials that surpass biology.”



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This alloy is kinky

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This alloy is kinky


Researchers have uncovered a remarkable metal alloy that won’t crack at extreme temperatures due to kinking, or bending, of crystals in the alloy at the atomic level.  A metal alloy composed of niobium, tantalum, titanium, and hafnium has shocked materials scientists with its impressive strength and toughness at both extremely hot and cold temperatures, a combination of properties that seemed so far to be nearly impossible to achieve. In this context, strength is defined as how much force a material can withstand before it is permanently deformed from its original shape, and toughness is its resistance to fracturing (cracking). The alloy’s resilience to bending and fracture across an enormous range of conditions could open the door for a novel class of materials for next-generation engines that can operate at higher efficiencies.

The team, led by Robert Ritchie at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, in collaboration with the groups led by professors Diran Apelian at UC Irvine and Enrique Lavernia at Texas A&M University, discovered the alloy’s surprising properties and then figured out how they arise from interactions in the atomic structure. Their work is described in a study that was published April 11, 2024 in Science.

“The efficiency of converting heat to electricity or thrust is determined by the temperature at which fuel is burned — the hotter, the better. However, the operating temperature is limited by the structural materials which must withstand it,” said first author David Cook, a Ph.D. student in Ritchie’s lab. “We have exhausted the ability to further optimize the materials we currently use at high temperatures, and there’s a big need for novel metallic materials. That’s what this alloy shows promise in.”

The alloy in this study is from a new class of metals known as refractory high or medium entropy alloys (RHEAs/RMEAs). Most of the metals we see in commercial or industrial applications are alloys made of one main metal mixed with small quantities of other elements, but RHEAs and RMEAs are made by mixing near-equal quantities of metallic elements with very high melting temperatures, which gives them unique properties that scientists are still unraveling. Ritchie’s group has been investigating these alloys for several years because of their potential for high-temperature applications.

“Our team has done previous work on RHEAs and RMEAs and we have found that these materials are very strong, but generally possess extremely low fracture toughness, which is why we were shocked when this alloy displayed exceptionally high toughness,” said co-corresponding author Punit Kumar, a postdoctoral researcher in the group.

According to Cook, most RMEAs have a fracture toughness less than 10 MPa√m, which makes them some of the most brittle metals on record. The best cryogenic steels, specially engineered to resist fracture, are about 20 times tougher than these materials. Yet the niobium, tantalum, titanium, and hafnium (Nb45Ta25Ti15Hf15) RMEA alloy was able to beat even the cryogenic steel, clocking in at over 25 times tougher than typical RMEAs at room temperature.

But engines don’t operate at room temperature. The scientists evaluated strength and toughness at five temperatures total: -196°C (the temperature of liquid nitrogen), 25°C (room temperature), 800°C, 950°C, and 1200°C. The last temperature is about 1/5 the surface temperature of the sun.

The team found that the alloy had the highest strength in the cold and became slightly weaker as the temperature rose, but still boasted impressive figures throughout the wide range. The fracture toughness, which is calculated from how much force it takes to propagate an existing crack in a material, was high at all temperatures.

Unraveling the atomic arrangements

Almost all metallic alloys are crystalline, meaning that the atoms inside the material are arranged in repeating units. However, no crystal is perfect, they all contain defects. The most prominent defect that moves is called the dislocation, which is an unfinished plane of atoms in the crystal. When force is applied to a metal it causes many dislocations to move to accommodate the shape change. For example, when you bend a paper clip which is made of aluminum, the movement of dislocations inside the paper clip accommodates the shape change. However, the movement of dislocations becomes more difficult at lower temperatures and as a result many materials become brittle at low temperatures because dislocations cannot move. This is why the steel hull of the Titanic fractured when it hit an iceberg. Elements with high melting temperatures and their alloys take this to the extreme, with many remaining brittle up to even 800°C. However, this RMEA bucks the trend, withstanding snapping even at temperatures as low as liquid nitrogen (-196°C).

To understand what was happening inside the remarkable metal, co-investigator Andrew Minor and his team analyzed the stressed samples, alongside unbent and uncracked control samples, using four-dimensional scanning transmission electron microscopy (4D-STEM) and scanning transmission electron microscopy (STEM) at the National Center for Electron Microscopy, part of Berkeley Lab’s Molecular Foundry.

The electron microscopy data revealed that the alloy’s unusual toughness comes from an unexpected side effect of a rare defect called a kink band. Kink bands form in a crystal when an applied force causes strips of the crystal to collapse on themselves and abruptly bend. The direction in which the crystal bends in these strips increases the force that dislocations feel, causing them to move more easily. On the bulk level, this phenomenon causes the material to soften (meaning that less force has to be applied to the material as it is deformed). The team knew from past research that kink bands formed easily in RMEAs, but assumed that the softening effect would make the material less tough by making it easier for a crack to spread through the lattice. But in reality, this is not the case.

“We show, for the first time, that in the presence of a sharp crack between atoms, kink bands actually resist the propagation of a crack by distributing damage away from it, preventing fracture and leading to extraordinarily high fracture toughness,” said Cook.

The Nb45Ta25Ti15Hf15 alloy will need to undergo a lot more fundamental research and engineering testing before anything like a jet plane turbine or SpaceX rocket nozzle is made from it, said Ritchie, because mechanical engineers rightfully require a deep understanding of how their materials perform before they use them in the real world. However, this study indicates that the metal has potential to build the engines of the future.

This research was conducted by David H. Cook, Punit Kumar, Madelyn I. Payne, Calvin H. Belcher, Pedro Borges, Wenqing Wang, Flynn Walsh, Zehao Li, Arun Devaraj, Mingwei Zhang, Mark Asta, Andrew M. Minor, Enrique J. Lavernia, Diran Apelian, and Robert O. Ritchie, scientists at Berkeley Lab, UC Berkeley, Pacific Northwest National Laboratory, and UC Irvine, with funding from the Department of Energy (DOE) Office of Science. Experimental and computational analysis was conducted at the Molecular Foundry and the National Energy Research Scientific Computing Center — both are DOE Office of Science user facilities.



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Giant galactic explosion exposes galaxy pollution in action

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Giant galactic explosion exposes galaxy pollution in action


A team of international researchers studied galaxy NGC 4383, in the nearby Virgo cluster, revealing a gas outflow so large that it would take 20,000 years for light to travel from one side to the other.

The discovery was published today in the journal Monthly Notices of the Royal Astronomical Society.

Lead author Dr Adam Watts, from The University of Western Australia node at the International Centre for Radio Astronomy Research (ICRAR), said the outflow was the result of powerful stellar explosions in the central regions of the galaxy that could eject enormous amounts of hydrogen and heavier elements.

The mass of gas ejected is equivalent to more than 50 million Suns.

“Very little is known about the physics of outflows and their properties because outflows are very hard to detect,” Dr Watts said.

“The ejected gas is quite rich in heavy elements giving us a unique view of the complex process of mixing between hydrogen and metals in the outflowing gas.

“In this particular case, we detected oxygen, nitrogen, sulphur and many other chemical elements.”

Gas outflows are crucial to regulate how fast and for how long galaxies can keep forming stars. The gas ejected by these explosions pollutes the space between stars within a galaxy, and even between galaxies, and can float in the intergalactic medium forever.

The high-resolution map was produced with data from the MAUVE survey, co-led by ICRAR researchers Professors Barbara Catinella and Luca Cortese, who were also co-authors of the study.

The survey used the MUSE Integral Field Spectrograph on the European Southern Observatory’s Very Large Telescope, located in northern Chile.

“We designed MAUVE to investigate how physical processes such as gas outflows help stop star formation in galaxies,” Professor Catinella said.

“NGC 4383 was our first target, as we suspected something very interesting was happening, but the data exceeded all our expectations.

“We hope that in the future, MAUVE observations reveal the importance of gas outflows in the local Universe with exquisite detail.”



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