Evaluation of the Altitude Variation of the Cosmic-ray Induced Environmental Neutrons in the Mt. Fuji Area

概要

論文の詳細を見る
To assess the natural background neutron dose rate in Japan, a series of measurements of the cosmic-ray induced neutron energy spectra and the neutron dose rates were carried out in the Mt. Fuji area (altitude: 40–3,700 m) by means of a Bonner multi-sphere neutron spectrometer (Bonner Spectrometer: BS) and a commercially available neutron rem-counter.The following results were obtained: (1) The neutron energy spectra at each altitude were almost the same in their shapes. (2) The total neutron fluence rate and the ambient dose equivalent H*(10) obtained by BS at sea level were estimated to be about 0.0075±0.00029 cm−2·s−1 and 6.4±0.25 nSv·h−1, respectively. (3) It was confirmed that the neutron fluence rate and the dose rate varied with the altitude according to an exponential law, ∼exp(αZ), where α=0.00071±0.00002 m−1 for the fluence rate and α=0.00070±0.00001 m−1 for the dose rate, respectively. These α-values were smaller than those obtained at high geomagnetic latitudes in other studies.
一般社団法人日本原子力学会の論文
2005-06-25