Testing a novel sensor design to jointly measure cosmic-ray neutrons, muons and gamma rays for non-invasive soil moisture estimation

Abstract

Abstract. Cosmic-ray neutron sensing (CRNS) has emerged as a reliable method for soil moisture and snow estimation. However, the applicability of this method beyond research has been limited due to, among others, the use of relatively large and expensive sensors. This paper presents the tests conducted to a new scintillator-based sensor especially designed to jointly measure neutron counts, total gamma-rays, and muons. The neutron signal is firstly compared against two conventional gas-tube-based CRNS sensors at two locations (Austria and Germany). The estimated soil moisture is further assessed at four agricultural sites in Italy based on gravimetric soil moisture collected within the sensor footprint. The results show that the signal detected by the new scintillator-based CRNS sensor is well in agreement with the conventional CRNS sensors and with the gravimetric soil moisture measurements. In addition, the muons and the total gamma-rays simultaneously detected by the sensor show promising features for a better correction of the incoming variability and for discriminating irrigation and precipitation events, respectively. Further experiments and analyses should be conducted, however, to better understand the added value of these additional data for soil moisture estimation. Overall, the new scintillator design shows to be a valid and compact alternative to conventional CRNS sensors for non-invasive soil moisture monitoring that can open the path to a wide range of applications.