Cosmic neutrons at ground: new spectral measurements at 3480 m a.s.l. and benchmarking of the cascade component as a function of the elevation at around 45° geomagnetic latitude

Within the INFN-based project SAMADHA, environment neutron spectrum measurements were performed at 3480 m a.s.l. on the Italian western Alps. An extended range Bonner Sphere Spectrometer was used, that was especially designed to operate unattended and to discriminate genuine neutron events from spurious ones. In addition to the measurements of neutron fluence rate, its energy distribution and the related ambient dose equivalent, as well as the arrival time distribution of the events were also studied. The high-energy component of the neutron fluence rate was compared to literature data measured with the same technique at similar latitudes as a function of the elevation, in turn being fitted with an exponential curve and compared to the results from EXPACS code. As the cascade component is not influenced by the materials surrounding the measurement site, this curve can be regarded as “universal” at the studied latitudes.