Spectrum Measurement of Natural Neutron in Tibet

The spectrum and ambient dose equivalent rate of outdoor natural neutron in Tibet were measured by multisphere neutron spectrometer and neutron ambient dose equivalent (rate) meter in this paper, and the spectra and ambient dose equivalent rates of the outdoor natural neutron with different altitudes were acquired. The results indicate that the spectrum shapes of the outdoor natural neutron almost remain unchanged, the fluence rate of each energy range increases with the altitude, and the total fluence rate, effective dose rate and ambient dose equivalent rate increase exponentially with the altitude. The effective dose rate can be acquired from the result of ambient dose equivalent (rate) meter multiplied by the spectrum-effective dose conversion factor.