"K2K - Physics with Accelerator-Produced Neutrinos Across Japan"


Tsuyoshi Nakaya

Associate Professor,

Graduate School of Science, Kyoto University


A neutrino is an important particle, which is one of the most abundant particles in our universe as similar as a photon. The K2K experiment is the first long baseline neutrino experiments to study neutrino oscillations. The goals of K2K are to confirm and establish the neutrino oscillations discovered in atmospheric neutrinos. The K2K uses an intense neutrino beam produced at KEK (High Energy Accelerator Research Organization) in Tsukuba. The neutrino detectors are constructed at KEK to measure the initial flux of neutrinos and to study interactions of neutrino with a nucleus. The neutrinos travel 250 km from KEK to Kamioka and are detected by a gigantic neutrino detector, called Super-Kamiokande. The K2K started data taking in 1999 and successfully collected data by March 2004. During this period, we had a big accident of Super-Kamiokande in 2001. With thankful help and supports from the world, we successfully recovered from the accident, and resumed the K2K experiment in 2002. At this forum, we will present the new result from K2K for the neutrino oscillation. The new result will enrich our knowledge of neutrinos since the neutrino oscillation is one of the most promising phenomena to access information of the mass. Before the results of K2K and Super-Kamiokande, it was difficult to explore the property since a neutrino is the lightest and less interactive particle.




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