A huge global scientific infrastructure is opening up underground in Japan to study matter, supernovae, and asymmetries in the universe.

Il July 31, 2025, under a mountain in the city of Hida, in the Japanese prefecture of Gifu, one of the most complex phases of the project has been concluded Hyper-Kamiokande: the excavation of the gigantic cave intended to house the main detector of the experiment. This is not just a construction step, but a decisive step forward for one of the most ambitious scientific infrastructure under construction today in the field of particle physicsThe underground cavity, dug at approximately 600 meters of depth, will have to accommodate a new generation tank filled with 260.000 cubic meters of ultra-pure water, designed to observe extremely rare phenomena and elusive particles such as neutrinos.

The work is coordinated by theTokyo University and KEK, High Energy Accelerator Research Organization, which leads the international collaboration of Hyper-KThe project involves 630 researchers di 22 Countries, with an Italian participation entrusted to theNational Institute of Nuclear PhysicsThe size of the collaboration is not an organizational detail: it indicates how much the contemporary fundamental physics it now depends on distributed scientific supply chains, specialized laboratories, extremely high-precision components and engineering capabilities that are difficult to concentrate in a single country.

Hyper-K was formally born in February 2020 as successor to Super-Kamiokande, one of the most influential experiments in the history of neutrino physicsThe new infrastructure, however, will have to operate on a much larger scale. The reservoir will have a volume of more than eight times greater compared to its predecessor and will be equipped with approximately 20.000 high-sensitivity photomultipliers, flanked by 800 multi-PMT modulesThese photosensors will be responsible for detecting the faint Cherenkov light produced when a charged particle, generated by the interaction of a neutrino with water, travels faster than light in the same environment.

A 69-meter cavity to capture tiny signals

The cave completed at Hida It has out of scale dimensions even for theunderground engineeringThe cylindrical section measures 69 meters in diameter it's almost 73 meters high, and is surmounted by a high dome 21 metersThe shape does not respond to a scenographic need, but to a functional constraint: to accommodate a water Cherenkov detector able to maximize the observable volume, reduce background noise and ensure mechanical stability in a deep rocky environment. The mass of the overlying mountain will also act as a natural screen against many cosmic particles, making the signal physicists were looking for cleaner.

The completion of the excavation represents an engineering curiosity and, at the same time, an indicator of the transformation of large scientific experiments into complex infrastructure projects. Before reaching the main cavity it was necessary geological studies, preliminary excavations, stability assessments, and careful planning of the construction sequence. In experiments of this type, the scientific data does not arise only from the algorithm or the sensor, but also from the quality of the concrete, the precision of the coatings, the cleanliness of the materials, the reliability of the electrical systems, and the risk management on construction sites.

"The construction of a detector like Hyper-Kamiokande demonstrates how the frontier of experimental physics has now also become an industrial frontier: it requires expertise in photonics, digitization electronics, precision mechanics, environmental control, and underwater systems integration. The challenge lies not only in producing individual advanced components, but in making them function for years within a huge, stable, and calibrated infrastructure, where any error can translate into experimental noise or loss of sensitivity."

Da August 2025, the next stage involves transforming the cavity into the large tank of the experiment. In 2026 the construction of the is planned real detector, while within the 2027 All internal components should be installed. Only after filling with ultra-pure water Hyper-K will be able to start operations as indicated for the 2028The timeline makes the incremental nature of the project evident: each phase prepares the next, but none can be accelerated beyond certain limits without compromising quality, safety or metrological reliability.

Italy in sensors, Switzerland in the CERN supply chain

Hyper-K's most visible innovation is the detector scale, but the most delicate part concerns the ability to transform very weak physical events into analyzable data. photomultipliers They are light-sensitive devices, designed to amplify extremely small signals. multi-PMT modules, composed of multiple integrated sensors, increase the granularity of the measurement and allow for a richer reconstruction of the tracks. In an experiment that observes extremely rare particles, the competitive advantage lies not in brute power, but in the combination of sensitive surface, low noise, time synchronization and processing capacity.

It is precisely at this technical level, less spectacular but decisive, that the Italian contribution. Italy, through theNational Institute of Nuclear Physics, not only participates in scientific collaboration: it intervenes in one of the most sensitive components of the apparatus, the one that must make extremely weak signals measurable within a gigantic volume of water. The section INFN of Naples It coordinates the contribution of the countries involved in the implementation of the multi-PMTs, including Canada, Poland, Czech Republic, Mexico e Greece.

Italy's centrality is also industrial and organizational. A new laboratory is being set up at the Naples branch of the INFN where the equipment will be assembled. more than a third of multi-PMT modules intended for Hyper-K. This is a fact that places the Italian participation not on the accessory level, but within the detector quality chain: assembly, integration, control and reliability of the modules are indispensable conditions for the experiment to be able to operate for years with metrological stability.

The reading is particularly interesting also for a Swiss newspaper like Innovating.News, because this supply chain does not end in Italy or in Japan.INFN he designed thedigitalization electronics of photomultipliers and is responsible for the production of 2.000 electronic cards. Starting from the middle of the 2026, these cards will be sent to the CERN, in the Geneva region, to be calibrated and integrated into underwater containers together with other electronic parts produced in South Korea, France, Japan, Poland, Spain, Switzerland e UK.

The point, therefore, is not to tell Hyper-K as an Italian national success, but as an example of European and global big science in which Italy carries out a highly specialized task and Switzerland enters the value chain through the CERN and the culture of scientific integration that revolves around the Geneva area. The operational chain well describes the new geography of advanced research: national planning, multilateral assembly, calibration in a European reference center and final integration in Japan.

For the tech industry, the most interesting spin-off is not necessarily an immediate product, but theaccumulation of skillsPhotodetectors, submerged resistant electronics, synchronization systems, waterproof containers, calibration procedures and constant quality check They feed an ecosystem of transferable knowledge. From this perspective, the Italian contribution should not be seen as a side note, but as a piece of Europe's ability to remain competitive in the advanced scientific instrumentation, in dialogue with international infrastructures such as CERN and with large experimental projects outside Europe.

From proton decay to CP asymmetry

The scientific program of Hyper-K is about some of the deepest questions of the contemporary physicsThe experiment will look for signs of proton decay, a phenomenon predicted by several formulations of the Grand Unification Theory but never observed. Its possible detection would have enormous implications, because it would indicate that ordinary matter is not stable in an absolute sense and would provide clues to a possible unification of the forze fondamentali at very high energies. The difficulty is that the phenomenon, if it exists, is extremely rare: enormous masses of observed material and long acquisition times are required.

A second strand concerns the CP violation, that is, the asymmetry between the behavior of the neutrinos and that of antineutrinosUnderstanding whether these particles oscillate differently may help explain why the observable universe is dominated by matter rather than antimatter. Hyper-K will analyze neutrino beams produced by the accelerator. J-PARC, located approximately 300 kilometers distance, and will compare them with the measurements obtained in nearby and intermediate detectors. The experimental logic is to observe how the beam changes along the path, reconstructing the oscillations between different types of neutrinos.

The project in fact includes multiple levels of observation. KEK is leading the upgrade of the J-PARC accelerator's neutrino beam and the construction of a new intermediate detector in the village of Tokai, in the prefecture of Ibaraki, less than a kilometer from the origin of the beam. An additional detector, located just 280 meters from the accelerator, integrates the architecture of the experiment. To the latter, INFN contributed with particular particle detectors known as Time Projection Chamber, instruments capable of reconstructing the trajectories of ionizing particles in a sensitive volume.

Hyper-K will also be a astrophysical observatoryNeutrinos generated by explosions of supernovae They can pass through dense regions of space and reach Earth, bringing information on the most violent phases of stellar life. Unlike light, which can be absorbed or delayed, neutrinos interact very little with matter and thus offer a complementary window on the universe. In this sense, the Japanese detector will function simultaneously as elementary particle microscope and how telescope for cosmic events.

Big science becomes an industrial platform

The history of Hyper-K confirms a now consolidated trend: the large scientific infrastructures they are not only places of discovery, but platforms of organizational innovationThe project connects universities, public institutes, national laboratories, specialized industries, and calibration centers. Its complexity requires shared standards, interoperability between components, process traceability, and governance capable of aligning contributions from different countries. It is a less visible form of innovation than digital innovation, but equally crucial for producing advanced knowledge.

In the market of scientific technologyExperiments like this are driving demand for high-reliability components and specialized engineering services. Photo-sensor manufacturing, front-end electronics, data acquisition systems, and ultrapure water treatment infrastructure are niche but strategic segments. They don't generate volumes comparable to consumer electronics, but they require performance, durability, and certifications that often anticipate future applications. medicine, environmental monitoring, of your digital ecosystem. , materials and scientific computing.

The choice to install the main detector at great depth, connecting it to a neutrino beam generated at 300 kilometers away and coordinating it with nearby detectors also shows how contemporary research is increasingly a distributed systemA single tool is not enough: we need distributed measurement chains, robust statistical models, simulations, reconstruction software and data infrastructures capable of distinguishing a significant event from millions of background signals. Innovation is therefore both hardware and methodological.

The schedule remains challenging. After excavation, the transition to the reservoir, installation of the internal components, calibration, and filling with ultra-pure water will lead, if the schedule is respected, to the start-up of the plant in 2028From that moment on, Hyper-K will not produce immediate answers, but a progressive collection of data destined to last for years. It is the long time of experimental science: an infrastructure investment built today to intercept signals that could redefine tomorrow's understanding of material,antimatter and evolution of the universe.

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