Cosmic Rays — highly energetic particles from space — bring us new knowledge about the nature; new species of elementary particles including dark matters, high-energy phenomena of the universe and signatures of past solar activities are notable examples. Through cosmic-ray observations we pursue a variety of interdisciplinary research topics between particle physics and astrophysics as follows:
a) The LHCf experiment: a study of hadron interactions with ultra high energy cosmic rays by using small, dedicated electro-magnetic calorimeters at the CERN Large Hadron Collider (LHC).
b) Underground experiments at the Kamioka mine: neutrino observations at Super-Kamiokande and dark matter searches at the XMASS experiment.
c) Underground experiments at the Gran Sasso Underground Laboratory (LNGS): direct dark matter detection and searches for the neutrinoless double beta decay at the XENON/DARWIN experiment
d) The SciCR Solar Neutron Telescope: Measurement of solar neutrons associated with solar flares by a massive scintillator hodoscopes at the top of a mountain in Mexico.
e) Measurement of radiocarbon (14C) contained in tree rings to probe solar activities in past periods (e.g., the Sporer and Wolf Minima).
f) The MOA experiment: Gravitational microlensing to search for exoplanets and MACHOs by using a dedicated 1.8 m optical telescope at New Zealand.
g) Gamma-ray observations: Investigation of origin and propagation of cosmic rays and search for dark matters with the Fermi gamma-ray satellite. Development of new gamma-ray instruments such as the Soft Gamma-ray Detector on board the ASTRO-H satellite and the Cherenkov Telescope Array.