title: Measurement for the dose-rates of the cosmic-ray components on the ground.
abstract: In this study, we aimed to measure the directly ionizing component (muons and photons) and the indirectly ionizing component (neutrons) of the cosmic-ray spectra and evaluate their dose rate contribution to the total dose rate on a ground level in Japan. Measurements were carried out in Tohoku University, Japan, from October 2000. The pulse-height spectra of the cosmic-ray photons and muons were measured with a 12.7 cm diameter and 12.7 cm long NaI(Tl) scintillation detector. In order to measure energy spectra of cosmic-ray photons and muons, response functions of the detector to photons and muons were determined by the Monte Carlo simulation codes. The cosmic-ray photon dose was evaluated directly from the measured pulse-height spectrum by using the spectrum weight function, and the cosmic-ray muon dose was evaluated by converting the measured pulse height spectrum into deposited energy within the detector. The quantity of the cosmic-ray electrons is estimated to be very small and is not taken into account in this study. The cosmic-ray neutron spectrum and the neutron dose were measured by using a multi-moderator spectrometer (Bonner ball) and a rem counter. The measurements could finally give the annual absorbed dose in tissue of the cosmic-ray muons of 315 microSv/y and annual ambient doses of the cosmic-ray photons and neutrons on the ground in Japan of 55 microSv/y and 31 microSv/y, respectively.
authors.affiliation: Department of Quantum Science and Energy Engineering, Tohoku University, Aza-aoba, Amaraki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Danielle A H
authors.initials: DA
authors.lastname: Rasolonjatovo
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Naoya
authors.initials: N
authors.lastname: Hirabayashi
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nunomiya
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Noriaki
authors.initials: N
authors.lastname: Nakao
mesh_terms: D001417:Background Radiation; D003359:Cosmic Radiation; D007564:Japan; D008651:Mesons; D009502:Neutrons; D017785:Photons; D011874:Radiometry