1/3/2023 0 Comments Brookhaven secrets![]() ![]() “More people moved into the field, not as their primary discipline, but as a way of finding new creative applications for their measurements,” says Zurek. Physicists, who first developed super-precise tools and lasers for studying and controlling single atoms and molecules, looked for more ways to use their new machines. Over the past decade or so, these tabletop approaches have become increasingly popular for dark matter searches, says Zurek. “We use these methods for other applications.” Compared to WIMP detectors, the tabletop experiments are simple and cost-effective, says Gehrlein. “This was a quick and interesting thing for us to do,” says Antypas. They usually use the equipment to study the weak nuclear force in atoms, which is responsible for radioactive decay. Looking for dark matter was actually a side project for his lab. In contrast, Antypas’ entire experiment fits on a tabletop, and his collaboration consisted of 11 scientists. To shield the detectors from unwanted radiation, physicists station them in laboratories deep inside mountains or underground in former mines. For example, the LZ detector in South Dakota contains 7 tons of liquid xenon, a rare element found in the atmosphere at less than 1 part per 10 million. Those experiments commonly involve collaborations of 100 scientists or more, and the detectors have dramatic engineering requirements. ![]() ![]() In addition, the team’s approach is distinctive compared to better-known dark matter experiments, which search for particles known as WIMPs (that’s weakly-interacting massive particles). However, their absence of a discovery does help constrain the properties of dark matter, as the experiment shows what dark matter is not. Like all other dark matter experiments so far, Antypas’ search hasn’t found anything. ”When people talk about ultralight dark matter, what they mean is that the dark matter is more like a wave,” says physicist Kathryn Zurek of the California Institute of Technology, who was not involved in the experiment. According to quantum mechanics, all matter has particle-like and wave-like qualities, with larger objects typically harboring more particle-like qualities and smaller ones more wave-like qualities. At its heaviest, an ultralight dark matter particle is still about a trillion times lighter than an electron. In particular, Antypas’ team uses their experiment to search for a class of dark matter known as ultralight dark matter. He hypothesized that the galaxies were held together with a type of invisible material, now called dark matter. At those speeds, gravity dictates that the galaxies should fall apart, like pancake batter whipping off a hand mixer. In 1933, the Swiss astrophysicist Fritz Zwicky observed galaxies that appeared to be spinning faster than their visible matter would allow. The team searches for fluctuations in fundamental constants to look for dark matter, a mysterious substance that physicists estimate makes up 85 percent of the matter in the universe. In addition, any fluctuations in fine structure constant are below 1 part in 100 trillion, says Antypas. Working with another team at Heinrich Heine University Düsseldorf, they find that if the mass of the electron did change, it fluctuated by less than 1 part in 100 trillion, and the mass of the iodine atom’s nucleus by less than 1 in 10 trillion. But in a paper published in Physical Review Letters this July, they report just how much several constants do not change. To be sure, Antypas’ team has not detected fundamental constants changing. ![]()
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