Despite their abundance—billions of neutrinos are thought to flow through human bodies every second, according to scientists—neutrinos are some of the most difficult particles to observe and measure in the universe. They barely interact with their surroundings, which makes them so elusive and difficult to spot. Surprisingly, this is actually their hidden strength. To find these elusive particles, astronomers have constructed some of the strangest observatories ever. One illustration comes from the KM3NeT, or Cubic Kilometre Neutrino Telescope, which is now being built in the Mediterranean Sea off the coast of Sicily, Italy.
Why detect neutrinos in the first place?
Neutrinos, often known as “ghost particles,” can transmit information about remote areas of the cosmos that would otherwise be degraded despite the fact that they are so difficult to detect. In fact, the very characteristic that makes them so difficult to find also makes them so useful as a tool for observation. Since neutrinos are mostly unaffected by matter and electromagnetic fields, they do not degrade as much as photons or other light particles do when they traverse the vastness of space. The James Webb Space Telescope and other cutting-edge space observatories may not be able to match the information that neutrinos could potentially deliver. Supernovae, star mergers, and other unusual cosmic occurrences can produce neutrinos, which could yield useful information.
Meet the KM3NeT underwater telescope
To find super-energetic neutrinos that have traveled from far-off galaxies, researchers are constructing KM3NeT beneath the Mediterranean Sea. When complete, it will be constructed of millions of spherical detectors suspended vertically from the ocean floor like kelp and connected to strings. As the name implies, KM3NeT will require the equivalent of 400,000 Olympic swimming pools in one cubic kilometer of water. It will consist of more than 6,000 spheres, each holding 31 photomultiplier tubes, which are extremely sensitive detectors. These independent ball-shaped spheres or telescopes are essential to the construction. One of these huge balls is seen being rolled into the ocean slowly in the video up top. They will then wait for radiation flashes that happen when the so-called ghost particles impact with the surrounding water, anchoring about three and a half kilometers beneath the surface of the ocean.
Why build KM3NeT beneath the ocean?
Because the Antarctic is a favorable location for the IceCube Neutrino Observatory, the ocean is a good place for the KM3NeT telescope. Since it began operation in 2011, the IceCube observatory has used detectors bored into a cubic kilometer of pure ice. The first proof that some neutrinos originate from blazars, a particularly energetic class of galaxy fueled by a black hole, was provided by observations from IceCube.
Cherenkov radiation flashes are sought after by the detectors utilized by KM3NeT and the IceCube observatory. This light is created when neutrinos interact with water or ice molecules. These flashes can be read by the detectors, providing information about the neutrino’s origin and possible formation processes.
Since water scatters light less than ice, the KM3NeT team chose to construct a submerged telescope instead of utilizing ice. This makes it simpler to determine the origin of the neutrinos with greater accuracy. There is less light to work with because water absorbs light more than air. As KM3NeT expands and continues to gather fresh information on the elusive ghost particles from the far-off universe, we will start to have a clearer understanding of the distinctions between the two observatories.