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The neutron sensor for field water measurement

Thanks to Cosmic Ray Neutron Sensing (CRNS) technology, our patented probe translates neutron interactions into reliable environmental data.

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The Physical Principle

From cosmic rays to water measurement

Cosmic Ray Neutron Sensing is based on a well-established physical interaction between neutrons and hydrogen atoms in water.

Cosmic rays

Cosmic rays interact with the atmosphere, generating fast neutrons that reach the Earth’s surface continuously.

Hydrogen Interaction

As fast neutrons interact with hydrogen atoms in water, they lose energy and become slow neutrons. The greater the moderation, the higher the water content in the surrounding soil or snow.

Neutron Detection

The probe measures neutron count variation and translates them into calibrated water content values in real time.

What Finapp did?

From research lab to the field: CRNS made operational

Cosmic Ray Neutron Sensing has measured water in soil and snow for years, locked inside research projects, custom builds and specialist know-how. Finapp patented a new generation of cosmic ray neutron sensors (CRNS) taking the technology out of the lab and into the field, where water decisions are actually made.

Built light. Built simple.

Compact, lightweight, datalogger on board. No trenching, no calibration rigs, no dedicated technician: install it on a pole and it starts measuring.

Muons: the built-in fact-checker.

Our probes count muons alongside neutrons, validating every reading in real time. Data you can act on the moment it arrives, not after days.

From particle counts to decisions.

Raw neutron counts help no one. Our interfaces turn them into answers: when and how much to irrigate, when a basin is approaching a risk threshold, how much water is stored in the snowpack.

The result: water intelligence, for everyone.

Growers, utilities and water authorities, not just physicists.

Measurement Advantage

Field-scale coverage meets subsurface depth

Subsurface Sensitivity

Insight below the surface

Since fast neutrons naturally penetrate approximately 30–50 cm into the soil, cosmic ray neutron sensor (CRNS) captures hydrogen-driven neutron moderation, revealing root-zone dynamics without inserting instruments into the soil.

  • 30–50 cm sensing depth
  • Root-zone monitoring
  • No soil disturbance

Field-scale footprint
point sensor
Representative Scale

Measuring areas, not isolated points

Traditional probes capture single locations. Since slow neutrons are able to travel across a 125–175 m radius, CRNS integrates their interactions over a large footprint, reflecting the real spatial variability of the field.

  • Footprint up to ~125 -175 m
  • Field-scale representativity
  • No sensor grids required
comparison

Measurement Methods Compared

Different technologies estimate water conditions in different ways. The cosmic ray neutron sensor combines wide-area coverage, subsurface sensitivity, real-time data, and non-invasive installation.
Finapp Probe TDR / FDR Probes Satellite Estimation
Measurement Scale + Field-scale representative x Point-based – Regional-scale covarage
Depth Coverage + Subsurface (0–50 cm) – Sub surface (0-100 cm) x Surface only (0-5 cm)
Representative Data + High x Low (single point) – Moderate
Installation Complexity + Single above-ground probe x Multiple probes required x None on site
Soil Disturbance + Minimal disturbance x Invasive v Non-invasive
Real-Time Data + Yes v Yes – Delayed
Continuous Monitoring + Yes v Yes (limited time) – Periodic updates
Scientific Foundation

Validated by research. Engineered for industry

The cosmic ray neutron sensor (CRNS) has been validated through nearly two decades of peer-reviewed research. Developed within the scientific community, it has become a proven technology for long-term, non-invasive environmental monitoring.

20+ years of scientific validation
Approved by FAO (Food and Agriculture Organization of the United Nations)
One technology for Soil Moisture & SWE
Trusted by researchers and industry worldwide