Improving Cosmic-Ray Neutron Sensing with neutron spectrometry

Investigating soil moisture on an intermediate scale (i.e., an area of some hectares and depth of tens of centimeters) can be achieved by measuring the flux of cosmic neutrons. This technique is called cosmic-ray neutron sensing and uses neutron counters to assess the water content in a field. Over the last year, the authors proposed an innovative neutron spectrometer to perform these measurements, which is called WEDDING-PIE (Wide Energy Detector for Direct Investigation of Neutron spectrum at Ground level for Precise moIsture Evaluation), abbreviated as W-PIE. Counters which are conventionally used can only give information on the intensity of the cosmic neutron flux, whereas a neutron spectrometer can calculate both the intensity and the neutron energy distribution. In this paper, the potential of the W-PIE for soil moisture measurements is described and the main advantages of using a neutron spectrometer over conventional neutron counters are illustrated. In conclusion, preliminary results of the measuring campaign in Parco Nord, Milan, are provided.