Study of the Environmental Neutron Spectrum at Zacatecas City

The environmental neutron spectrum has been measured at Zacatecas City in Mexico. Neutron spectrum was unfolded from count rates obtained with a multisphere neutron spectrometer with a LiI(Eu) scintillator. With the spectrum information the ambient dose equivalent and the isotropic effective dose were calculated. A model based upon the geomagnetic latitude and the altitude above sea level, that allows to estimate the neutron fluence rate is proposed, the model results are compared with total neutron fluences measured at several locations worldwide. Environmental neutron spectrum shows peaks at 1 and 100 MeV as well as a relevant amount of low energy neutrons. The neutron fluence rate was 65 ± 3 cm-h, producing 13.7 ± 0.6 nSv-h due to ambient dose equivalent rate and an isotropic effective dose rate of 14.1 ± 0.6 nSv-h. Neutron fluence rates predicted with the model are in agreement with those reported in the literature.