Kazuyoshi KobayashiView profile
Associate Professor
Kazuyoshi Kobayashi is an Associate Professor at Waseda University’s Faculty of Science and Engineering and a researcher in the Research Institute for Science and Engineering. He is an experimental astro-particle physicist whose work spans space-borne cosmic-ray calorimetry, direction-sensitive dark-matter searches, and ultra-low-background detector R&D. His scientific output includes 149 refereed papers and an h-index of 56 (Scopus, Sept 2025). Education: 1993 – 1997: B.S. in Physics, University of Tokyo 1997 – 2002: Ph.D. in Physics (cosmic-ray and particle physics), Graduate School of Science, University of Tokyo Research interests: Kobayashi addresses fundamental questions about the origin, acceleration and propagation of cosmic rays by measuring their elemental spectra (proton to nickel) from tens of GeV to hundreds of TeV with the CALET instrument on the International Space Station. Parallel to this, he develops and operates underground detectors to hunt for weakly interacting massive particles (WIMPs) and studies neutrino properties using large liquid-xenon and water-Cherenkov observatories. His technical expertise includes low-radioactivity photomultiplier tubes, micro-pattern gas detectors (µ-PICs), radon-emanation screening, and advanced statistical inference for rare-event searches. Publication trends (2020-2023): His recent articles concentrate on (i) precision cosmic-ray spectroscopy (electrons, protons, helium, boron, carbon, oxygen, nickel, iron) revealing spectral hardenings and charge-sign dependent solar modulation, (ii) world-leading dark-matter limits from XENON1T/XENONnT and XMASS-I covering nuclear recoils, electronic recoils, inelastic scattering and bosonic models, and (iii) multi-messenger follow-ups of gravitational-wave events with CALET and Super-Kamiokande. These works combine high-statistics space data with ultra-low-background underground measurements to probe both astrophysical and particle-physics phenomena. Awards & recognition: No named prizes are listed in the supplied text; however, his membership in the CALET, XENON, XMASS, NEWAGE and Super-Kamiokande collaborations, coupled with his role as corresponding analyzer for multiple high-impact papers, signifies strong peer recognition. Advising & grants: While formal student names and grant numbers are not published on the profile page, Kobayashi is regularly designated as analysis coordinator or corresponding author for graduate-student datasets, indicating active supervision of PhD and master’s students. His projects are supported by Japanese JSPS KAKENHI grants and international collaboration funds. Labs & teams: He leads the Japanese CALET operations team at Waseda, contributes to the XENON/XMASS low-background working groups, and heads detector R&D for the NEWAGE direction-sensitive TPC. These teams operate instruments at the Kamioka Underground Observatory and aboard the ISS, with ongoing upgrades toward XENONnT and future GADZOOKS!-style neutron-tagging phases of Super-Kamiokande.










