@misc{oai:repo.qst.go.jp:00069900,
 author = {Yajima, Kazuaki and Yasuda, Hiroshi and 矢島 千秋 and 保田 浩志},
 month = {Oct},
 note = {Cosmic neutrons are main contributor to cosmic radiation exposure, achieving about a half of total effective dose at aviation altitude. There have been many experiments of cosmic neutron measurement in aircraft and at high mountain but not so many reports about the energy spectrum, which is necessary to determine accurate cosmic-neutron dose. The energy spectrum measurements were performed using a multi-moderator spectrometer, so-called Bonner ball detector, so far. However, there is still some uncertainty in those results particular in the high-energy region. Therefore, we tried to measure precise cosmic-neutron energy spectrum using a phoswich-type detector and to verify the cosmic-neutron energy spectra that were measured with Bonner ball detectors. 
The measurement was performed in the Mt. Fuji Weather Station built at the summit of Mt. Fuji (3,776 m above see level) from July to August, 2008. It is expected that the cosmic-neutron ambient dose equivalent rate is about 10 times greater there than that at the sea level.  The phoswich-type detector has a 160 mm x 160 mm probe consisting of liquid scintillator and plastic scintillator. The signals of neutron were discriminated from those of other particles analyzed based on the difference of the decay time between the liquid scintillator and the plastic scintillator. Then unfolding with the FERDO-U code was performed. In order to obtain precise energy spectra, the response functions, precise particle discrimination technique and unfolding program are discussed., 11th Neutron and Ion Dosimetry Symposium (NEUDOS-11）},
 title = {Measurement of Cosmic Neutron Energy Spectrum at the Summit of Mt. Fuji},
 year = {2009}
}