matter – Physics for you

on June 17, 2021June 17, 2021Articles

Physicists have created a new form of matter

Scientists at the Massachusetts Institute of Technology in the United States have created a superfluid solid from sodium atoms. For this purpose, they used lasers, …

on June 13, 2021June 13, 2021Articles

Clue "dark" matter

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on June 8, 2021June 8, 2021Articles

Scientists have discovered a new form of matter: liquid glass

Researchers from the University of Constance (Germany) have been able to simulate the structure and behavior of a new form of matter. It got the …

About four years ago, I wrote a short post about Columbia University professor Elena Aprile and her project to search for XENON dark matter particles. She then believed that "over the next couple of years, maybe five or six in total, we will either say for sure that WIMPs do not exist, or we will discover something." And so, perhaps, they really discovered something! © XENON experiment The heart of the detector is a chamber filled with 3.5 tons of xenon. XENON is the most sensitive detector at the moment, aimed at finding dark matter particles. Its current modification XENON1T is 3.2 tons of liquid ultrapure xenon (just to understand the technical complexity of the experiment: xenon can only be in liquid form in a very narrow temperature range from -108 to -111 ° C). The xenon tank is located deep underground in the mountains of Italy and surrounded by sensitive sensors. Initially, the project was actually looking for WIMPs - these are such popular hypothetical candidates for dark matter particles with a large mass, which, it is assumed, can weakly interact with xenon nuclei. But for more than 10 years (before loading several tons of xenon, they started with small detectors) they have not found anything like that. And then they realized that using the same setup, one could look for a slightly different type of hypothetical particles called axions. These particles are much lighter, and they are looked for by their effect on electrons. The problem here is that a lot of ordinary things interact with electrons: for example, electrons from the beta decay of radioactive atoms in a rock. But these ordinary events can be more or less accurately assessed and see if there is anything else in the signal. It turned out that it seems as it is: instead of the expected 232 ± 15 events, we saw 285 - this is an excess of 3.5σ (this roughly means that the chance that the excess is a coincidence of circumstances is something about 0.02%). In the physics of elementary particles, this is not yet a discovery, but it is very close to it (for a discovery, 5σ is required, which corresponds to an error probability of ~ 10⁻⁵%). © XENON Collaboration Measurement results with the XENON1T detector. A strong excess over the background (red line) is noticeable for an energy of about 2 keV. Other explanations, of course, are also possible. For example, ordinary neutrinos can give the same signal if they suddenly have a large magnetic moment - no one knows its value, and if it really turns out to be so large, then this in itself will be extremely interesting and unexpected. There is, however, a trivial explanation - the signal is caused by tritium contamination. This is the only banal reason that scientists could not completely exclude due to the difficulty of detecting tritium. In fact, this isotope of hydrogen, due to its high radioactivity, is extremely rare: in xenon, according to estimates, it should not have more than 1 atom per 10²⁵ of xenon atoms, but this may be enough to explain a good half of the observed signal. Apparently, the only way to exclude this explanation is to find a similar signal by other methods. Preprint of the article: E. Aprile et al. (XENON Collaboration) Observation of Excess Electronic Recoil Events in XENON1T

on June 3, 2021June 3, 2021Articles

XENON1T detector may have detected dark matter particles axions

About four years ago, I wrote a short post about Columbia University professor Elena Aprile and her project to search for XENON dark matter particles. …

on June 3, 2021June 3, 2021Articles

Physicists first got the state of matter predicted almost 50 years ago

The elusive excitony, the existence of which could not be experimentally proven for almost half a century, finally showed itself to researchers. This is reported …

updated on June 3, 2021June 3, 2021Articles

FASER experiment will study particles interacting with dark matter

The FASER experiment will be ready to collect collision data at the Large Hadron Collider when they resume in spring 2022 The newest experiment at …

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