One of the greatest scientific search of our time- this is the hunt for dark matter. Physicists believe that this substance fills the universe and think they can see evidence of this in how galaxies rotate. The fact is that galaxies rotate so fast that they had to be torn apart, but apparently (or invisibility) there is some hidden mass that has enough gravitational force to hold them together.
This forced physicists to search for dark matter onEarth They built dozens of observatories, most of which are located in underground caves deep below the surface, where the background noise is low. Scientific fame is at stake, and those who find dark matter will be richly rewarded.
Why can't dark matter be found?
So far, physicists have not found anything. If dark matter exists, it is extremely well hidden. One possibility is that dark matter particles are too small to be found in ongoing experiments. Physicists desperately want to find a more sensitive way to search for similar substances.
Yonit Hochberg from Hebrew University inJerusalem in Israel and its colleagues have developed a promising new sensor based on tiny superconducting wires. The team prototype already shows the potential of such an approach.
The basis of the new device is a simple principle. Cool certain metals below the critical temperature and they will conduct electricity without resistance. But as soon as their temperature rises above this threshold, the superconducting behavior disappears.
Physicists know that dark matter particles cannotinteract strongly with visible matter; otherwise they would have seen them. But dark matter particles can collide with ordinary particles.
This collision is rare becauseordinary matter is mostly empty space, and particles of dark matter can pass right through it. But when they collide with an atomic nucleus or an electron in a lattice, for example, a collision causes vibrations in the lattice, thereby increasing its temperature.
It is this temperature rise that is good.superconducting nanowires are detected. Heating leads to the fact that a small part of the wires ceases to be superconducting, and this, in turn, creates a voltage pulse that is easy to measure. Moreover, such a device produces few false positives, if any.
Hochberg and colleagues tested their idea by creatingprototype. This device consists of a set of tungsten silicide nanowires only 140 nanometers wide (for comparison, the width of a human hair is about 100 000 nanometers) and 400 micrometers long. The entire apparatus is only a few milligrads above absolute zero, so that tungsten silicide wires become superconductors.
The team then watched voltage pulses,which could reveal the collision of dark matter. With appropriate shielding, they did not detect any pulses within 10,000 seconds of measurements.
This imposes important restrictions on the type of darkmatter, which could exist, and its density. It also imposes restrictions on other types of particles that physicists assume may exist.
One of these types - “dark photon”, in fact,the equivalent of an ordinary dark matter photon. If any, the new detector has not detected one. “The results obtained with this device already set significant limits for the interaction of dark matter with electrons, including the strongest terrestrial boundaries for absorbing such photons at less than eV,” says Hochberg.
The work is impressive, given that the massnanowires is just a few nanograms. The next step will be their manufacture on a larger scale. Hochberg and colleagues say that the technology is relatively mature, so it can be tested in a short time. According to their estimates, the scientific laboratory will be able to produce one thousand 200-nanometer detectors with a total mass of 1.3 grams in just one year. Therefore, a kilogram detector may well be feasible in the near future.
Maybe one day, superconducting nanowires will detect dark matter, if it exists. What do you think exists? Tell us in our chat in Telegram.