Altitude variation of cosmic-ray neutrons.
The altitude variation of the cosmic-ray neutron energy spectrum and the dose equivalent rate was measured at an average geomagnetic latitude of 24 degrees N by using the high-efficiency multi-sphere neutron spectrometer and neutron dose-equivalent counter developed by the authors. The data were obtained from a 2-h flight over Japan on 27 February 1985. The neutron energy spectra measured at sea level and at altitudes of 4,880 m and at 11,280 m were compared with the calculated spectra of O'Brien and with other experimental spectra, and they are in moderately good agreement with them. The dose equivalent rate increases according to a quadratic curve up to about 6,000 m and then increases linearly between 6,000 m and 11,280 m. The dependence of dose equivalent rates at sea level and at an altitude of 12,500 m on geomagnetic latitude also is given by referring to other experimental results.
Nakamura
T
T
Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan.
Uwamino
Y
Y
Ohkubo
T
T
Hara
A
A
D000531:Altitude; D003359:Cosmic Radiation; D005843:Geography; D009502:Neutrons; D011829:Radiation Dosage; D011834:Radiation Monitoring