Nagaoka K, Hiraide I, Sato K, Nakamura T
Japan Chemical Analysis Center (JCAC), 295-3 Sanno-cho, Inage-ku, Chiba-shi, Chiba 263-0002, Japan.
Radiat Prot Dosimetry. 2008;132(4):365-74. doi: 10.1093/rpd/ncn316. Epub 2009 Jan 16.
Cosmic-ray dose rates on the ground were measured throughout Japan. Neutron dose rates were measured as ambient dose equivalent rates (H*(10)) at 240 points using high-sensitivity neutron REM counters. In addition, cosmic rays directly ionising plus photon components were measured with an ionisation chamber. Time variation due to solar modulation during this study was corrected based on the results of sequential measurements. The effects of altitude, geomagnetic latitude, rainfall and snowfall on the neutron dose rate were inferred from the measured results. The mean value of the neutron dose rates (H*(10)) measured at 47 points of prefectural capitals in Japan was 4.0 nSv h(-1). The value corrected for the energy response of the REM counter was 6.4 nSv h(-1), corresponding to 4.8 nSv h(-1) as an effective dose (ISO). The mean value of the cosmic ray directly ionising plus photon components as an effective dose was 31 nSv h(-1).
在日本各地测量了地面上的宇宙射线剂量率。使用高灵敏度中子REM计数器在240个点测量中子剂量率，作为环境剂量当量率（H*(10)）。此外，用电离室测量宇宙射线直接电离加光子成分。根据连续测量结果校正了本研究期间由于太阳调制引起的时间变化。从测量结果推断出海拔、地磁纬度、降雨和降雪对中子剂量率的影响。在日本47个省会城市测量的中子剂量率（H*(10)）的平均值为4.0 nSv h(-1)。针对REM计数器的能量响应校正后的值为6.4 nSv h(-1)，对应于作为有效剂量（ISO）的4.8 nSv h(-1)。宇宙射线直接电离加光子成分作为有效剂量的平均值为31 nSv h(-1)。
