Beyond Helium-3: Instruments for Cosmic-Ray Neutron Sensing based on Boron-10 Neutron Detectors

Cosmic-Ray Neutron Sensing (CRNS) has become a standard method for non-invasive soil moisture monitoring at the field scale. With most CRNS sensors being derivatives from scientific nuclear equipment, the development of instruments based on alternative neutron detection technologies is a major development goal for CRNS. We present a modular instrument family based on boron-10-lined proportional counters, specifically designed for long-term autonomous field operation. The system is controlled by a data logger supporting various telemetry options and external SDI-12 environmental sensors and the frontend electronics with its pulse shape analysis effectively separates neutron signals from background and electronic noise. Our results show high energy efficiency, with the latest generation close to 50 mW, allowing solar-powered operation even in challenging environments. The performance of the instruments has been validated within long-term field deployments in different settings, showing that boron-10-based systems provide a scalable, cost-effective and reliable alternative for the next generation of CRNS monitoring networks.