Experimental Measurements of the Cosmic-Ray Induced Neutron Spectra at Various Mountain Altitudes With HERMEIS

Measurements performed with the High Energy Range Multisphere Extended IRSN System (HERMEIS) acquired by the French Aerospace Lab are presented and discussed. The detectors were calibrated at the Low Noise Underground Laboratory of Rustrel. Atmospheric neutron spectra were obtained at three altitudes ( ${+}500$ m, ${+}1000$ m and ${+}2885$ m) and the first results about the continuous measurements of the Natural Radiative Environment at the Pic du Midi are presented with a discussion about the uncertainties.