There are nineteen countries interested in participating in this project led by Japan. Spain is the second country to sign the MoU, after Poland signed in February. UTokyo President Teruo Fujii, KEK Director General Masanori Yamauchi, and Research Secretary General of the Ministry of Science and Innovation Raquel Yotti signed the MoU during the month of August through an exchange by mail.

According to the MoU, the Spanish Hyper-Kamiokande Consortium is made up of nine institutions: the Centro de Astropartículas y Física de Altas Energías (CAPA) of the Universidad de Zaragoza, the Centro Internacional de Física de Donostia (DIPC), the Institut de Física d’Altes Energiess (IFAE), the Laboratorio Subterráneo de Canfranc (LSC), the Universidad Autónoma de Madrid (UAM), the Universitat de Girona (UdG), the Universidad de Oviedo (UO), the Universidad Politécnica de Valencia (UPV) and the Universidad de Santiago of Compostela (USC). These institutions are expected to contribute through the development, production and installation of the photosensor protection covers, the ventilation system, the geomagnetic compensation system, electronic circuit modules, radiation sources for calibration and different elements of the near detector.

The Hyper-Kamiokande detector is expected to have eight times the mass of its predecessor, the Super-Kamiokande, and will be equipped with newly developed high-sensitivity photosensors. The construction budget was approved in the Japanese Parliament in February 2020, marking the official start of the project. Construction began in May 2021 with the excavation of the access tunnel to the experimental area.

A part of the Spanish contribution to the HKK project will be financed with funds from the Plan de Recuperación, Transformación y Resiliencia (PRTR), as one of the actions of the line of strengthening the capacities, infrastructures and equipment of the agents of the Spanish System of Science , Technology and Innovation through the promotion of new actions in large European and international research infrastructures. The action will benefit the Spanish industry, which will be responsible for the development of the detector’s components and will allow the participation of Spanish research groups in the scientific exploitation of HKK.