Commentary by Professor Mariusz Wójcik, PhD, DSc, Eng., of the Interdepartmental Institute of Radiation Technology, Faculty of Chemistry, Lodz University of Technology:
Neutrinos are elementary particles that have been known to physicists since the mid-twentieth century. They are fundamental to the construction of the so-called Standard Model, which remains the best and, so far, unchallenged explanation of the structure of matter and the nature of the interactions governing it, with the exception of gravity. However, neutrinos differ significantly from the elementary particles that make up atoms and are familiar to us all. They have an extremely small mass, and their possible interactions with matter are extraordinarily weak. For this reason, detecting them is a major challenge, despite the fact that they pass through the Earth in vast cosmic numbers at every moment. Since the probability of a neutrino colliding with an atom is extremely low, observing such collisions requires detectors of enormous size. Moreover, they must be made from a pure material with suitable properties and relatively little susceptibility to interference from other radiation particles.
The idea that brought Professor Halzen the Nobel Prize was to use the immense masses of ice covering Antarctica as a neutrino detector. On his initiative, a detector known as IceCube was built between 2005 and 2010 at the Amundsen–Scott scientific station at the South Pole. Across an area extending over several kilometres, dozens of “wells”, 1.5 to 2.5 km deep, were melted into the ice. Sensitive detection instruments based on photomultiplier tubes were then lowered into them. In the anticipated collisions between neutrinos and water molecules, fast electrons may, among other things, be emitted. These, in turn, can generate signals in the photomultiplier tubes. The IceCube detector has fulfilled the expectations placed in it and continues to be expanded. Over the years, it has enabled, among other achievements, the direct detection of neutrinos with extremely high energies, reaching teraelectronvolt levels. These results are revolutionising contemporary astrophysics.
When reflecting on discoveries concerning neutrinos, it is also worth mentioning another related problem in contemporary physics: explaining the nature of so-called
dark matter. According to current theories based on astronomical observations, dark matter constitutes most of the Universe. One possible form of dark matter is believed to be the so-called WIMPs (Weakly Interacting Massive Particles). Like neutrinos, they have an extremely low probability of colliding with atoms and have therefore remained elusive to date. Large-scale detectors based on liquefied noble gases, placed deep underground, are used in the search for dark-matter particles. In September 2026, the scientific community received news that, after many years of research, one (!) collision had been observed in the LUX-ZEPLIN detector in the United States, which is based on liquefied xenon. This event would most likely be attributable to a WIMP particle. However, the finding still requires confirmation.
It is worth adding that work related to the detection of WIMP particles is also being carried out at the Interdepartmental Institute of Radiation Technology, Faculty of Chemistry, Lodz University of Technology. We are participating in the international DarkSide project, whose aim is to construct a large-scale elementary-particle detector based on liquefied argon. The detector will be located deep underground at the Gran Sasso National Laboratory in Italy.
Our contribution to the DarkSide project concerns methods for modelling physicochemical processes related to electron transport in liquefied argon. If interactions involving dark-matter particles can be observed in liquefied argon, it will attract considerable attention.