Kamioka ObservatoryICRR, The University of Tokyo

The Koshiba Prize is one of the awards established by the Foundation for High Energy Accelerator Science. It is given to researchers who have made outstanding contributions to the development of measurement technology in fundamental sciences, particularly in the field of particle physics, demonstrating exceptional originally, and earning high international recognition.

For the 2024 Koshiba Prize, Associate Professor Hiroyuki Sekiya, the spokesperson for the Super-Kamiokande experiment, has been selected. This award recognizes his achievements in the development of supernova neutrino observation technology at Super-Kamiokande.

Since 2020, Super-Kamiokande has been working to enhance its neutrino detection sensitivity by adding gadolinium to approximately 50,000 tons of ultrapure water. This effort improves the accuracy of determining the arrival direction of neutrinos in the event of a supernova explosion within the Milky Way galaxy. Furthermore, it aims to achieve the world’s first detection of supernova relic neutrinos—neutrinos originating from supernova explosions accumulated since the early universe.

Associate Professor Sekiya has served as the head of Super-Kamiokande’s water purification system and has been one of the leaders of the gadolinium project since 2014. He played a key role in technological developments, including the creation of a resin that maintains water transparency while retaining gadolinium and the establishment of a method to produce gadolinium sulfate with minimal radioactive impurities. His contributions in these areas have been highly recognized.

The introduction of gadolinium significantly enhanced the identification efficiency of anti-electron neutrinos, one of the six types of neutrinos. As a result, in the case of a supernova explosion occurring near the center of the Milky Way, Super-Kamiokande became possible to pinpoint the direction of the emitted neutrinos with an accuracy of approximately 3 degrees within 90 seconds, allowing timely alerts to observatories worldwide. This breakthrough is expected to contribute significantly to the advancement of multi-messenger astronomy. Furthermore, in the search for supernova relic neutrinos, background components such as electron neutrinos are suppressed, allowing the detection of potential signals. Associate Professor Sekiya’s significant contributions to these improvements of Super-Kamiokande have been duly recognized, leading to this prestigious award.

Upon receiving the award, Associate Professor Sekiya commented; “As a researcher working in Kamioka, I am deeply honored to receive the Koshiba Prize. The realization of the Super-Kamiokande Gadolinium Project (SK-Gd) is the result of years of dedicated effort by many individuals, including past and present members of the Water Team, SK collaborators, and numerous companies, such as those involved in water purification systems and rare earth manufacturing. I consider this award a recognition of our collective achievements.
Looking ahead, we will continue our research using the upgraded Super-Kamiokande to achieve the first detection of the diffuse supernova neutrino background and to observe neutrinos from supernova explosions within the Milky Way, enabling timely alerts to other observatories. I sincerely appreciate your continued support for Super-Kamiokande.”

Links
Foundation for High Energy Accelerator Science
Completion of additional Gd introduction into Super-Kamiokande (July 8, 2022)