Finapp Cosmic Ray Neutron Sensor
CRNS for soil water content and snow water equivalent
Page Contents
Incoming measurement in situ
The detector developed and patented by Finapp is based on a plastic scintillator material (ZnS:Ag), which can detect charged particles doping with lithium to gain the capability of detecting low-energy neutrons. By pulse shape discrimination, Finapp is therefore capable of contextually detecting neutrons and muons or electrons, which suggested a new approach to obtain a site-specific incoming correction. Muons are also generated by cosmic rays, but they are not back-scattered by the soil like neutrons are, which makes them suitable for monitoring the incoming flux itself. Scientific papers showed that the muon count rate is generally correlated with the incoming neutron flux (Stevanato et al. 2022) and that it can be successfully applied as incoming correction for CRNS applications (Gianessi et al. 2024). There is evidence indicating that the muon flux measured by Finapp probes is consistent with the neutron flux data published by the Neutron Monitor Database (NMDB) network. The additional measurement of mouns allows the normalization of the flux of incoming cosmic rays, enabling a in situ validated, real-time measurement of soil moisture content, without the need of a reference of the neutron monitor database, essential in equator African region where there are no NMDB stations. Finapp is the only manufacturer of CRNS (Cosmic Ray Neutron System) devices that include muons detection, thanks to the following patents:- – 102019000000076 (Italian identification number), resulting from PCT/IB2019/061282 and extended to EU 19839276.3 (European patent number)
- – 102021000003728 (Italian identification number), resulting from PCT/IB2022/051238
How the Cosmic Ray Neutron Sensing Finapp probe works
Neutron sensing technologies count slow neutrons that have been thermalized by collision of fast neutrons or cosmic rays with hydrogen in the soil and which have bounced back to the slow neutron detector. The detectors only count returning slow and has been patented to count muons for the incoming real time and in situ correction. The count of the slow neutrons indicates the number of hydrogen atoms that have been recorded at a particular soil depth. The major source of hydrogen in soil is within water, and so small changes in soil moisture can be monitored continuously as changes in hydrogen content in the soil and thermalised neutron density.
The probe counts the neutrons available at a given time, based on the quantity of water present in that area and the availability of cosmic radiation. This involves the measurement of the incoming cosmic rays (which are fast moving neutrons). The Finapp measures a subatomic particle related to the cosmic neutron: the moun.
With the addition of an ICT International MFR-Node, the Finapp can be converted to an IoT device compatible with other sensors to measure key soil, plant, and environment parameters.
About Fast and Slow Neutrons
The Finapp detector contains Lithium-6; when a neutron hits the detector, a pulse of light is generated and energy is released. Within the detector, a photo-multiplier converts the light to an electronic signal for interpretation within the Finapp.
Incoming fast muon particles are measured by the detector, as they are electrically charged. The difference between the muons (incoming) and the slow (returning) neutrons will give the final measure of soil moisture. Any decrease in neutron count is related to the increase in soil.
About Gamma Ray measurements (Finapp-Monitor only)
Measurement of gamma rays is also possible with the Finapp-Monitor. This measurement allows for precipitation to be detected.
Specifications
Standard Finapp Probe
| Probe | Finapp-SM | Other models available – see below |
| Use | Agriculture, Snow Water Equivalent, Hydrological Bills, Environmental monitoring (landslides, wildfires and floods) Forests, and Slow Changing Environments |
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| Neutrons Count
*Each rate is generally achievable at sea level, under standard pressure (NTP), with an air humidity of 10 g/m³ and a volumetric soil moisture content of 10% at a latitude of 51° north. |
1000/h | |
| Mouns Count
*Each rate is generally achievable at sea level, under standard pressure (NTP), with an air humidity of 10 g/m³ and a volumetric soil moisture content of 10% at a latitude of 51° north. |
4000/h | |
| Enclosure | For soil moisture: Anti-UV polycarbonate IP67 enclosure of 40x30x18cm. Including brackets for anchoring to 48-50mm pole For Snow Water Equivalent: : Box Plastic IP67, 40x30x18cm + Box AlluminiumIP68, 40x31x18cm Including brackets for anchoring to 48-50mm pole |
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| Power | Depending on the site, normally the Battery (18Ah) and Solar Panel (20W). The configuration can be adjusted according to the requirements of the specific site. | |
| Range of Operation | -60°C to + 60°C |
Other Finapp Probes available
| MODEL | DEFAULT CONFIGURATION |
| Finapp Soil Moisture (SM) | • 1,000 neutrons/h* and 4,000 muons/h* at standard conditions • IP67 enclosure (30 × 40 × 18 cm) • 9 Ah battery and 20 W photovoltaic panel, charger • Mounting brackets for 48–50 mm poles • Temperature, pressure and relative humidity sensors • GSM/LTE Data transmission via API, FTP or Finapp Cloud, where mobile coverage is available • SD card for local data storage |
| Finapp SM Plus | • 2,000 neutrons/h* and 8,000 muons/h* at standard conditions • IP67 enclosure (50 × 40 × 20 cm) • 18 Ah battery and 20 W photovoltaic panel, charger • Mounting brackets for 48–50 mm poles • Temperature, pressure and relative humidity sensors • GSM/LTE Data transmission via API, FTP or Finapp Cloud, where mobile coverage is available • SD card for local data storage |
| Finapp SM Premium | • 4,000 neutrons/h* and 16,000 muons/h* at standard conditions • IP67 enclosure (50 × 40 × 20 cm) + one battery IP67 box (30x40x18cm) • 50 Ah battery and 40 W photovoltaic panel, charger • Mounting brackets for 48–50 mm poles • Temperature, pressure and relative humidity sensors • GSM/LTE Data transmission via API, FTP or Finapp Cloud, where mobile coverage is available • SD card for local data storage |
| Finapp Snow Water Equivalent (SWE) | • A pair of probes for measuring SWE – water content in the snow – in real time, over an area with a radius of approx. 20m, with saturation >10’000 mm/eq.
• 1,000 neutrons/h* and 4,000 muons/h* at standard conditions |
| Finapp SWE+SM | • A pair of probes for measuring SWE and SM: 1. SWE – snow water equivalent – in real time, over an area with a radius of about 20m, with saturation >10’000 mm/eq.2. SM – soil moisture in real time over an area of 5-20 ha approximately, up to a depth of 50cm, when the ground is not covered with snow. • 1,000 neutrons/h* and 4,000 muons/h* at standard conditions • one IP67 enclosure (40x30x18 cm) for on air probe and one aluminum IP68 (40x31x18 cm) for on ground probe • 18 Ah battery and 20 W photovoltaic panel, charger • Mounting brackets for 48–50 mm poles • Temperature, pressure and relative humidity sensors • GSM/LTE Data transmission via API, FTP or Finapp Cloud, where mobile coverage is available • SD card for local data storage |
| Rover
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• Maps of soil moisture with a maximum resolution of 10×10 m. • 4,000 neutrons/h* and 16,000 muons/h* at standard conditions • IP67 enclosure (50 × 40 × 20 cm) + one battery IP67 box (30x40x18cm) • 50 Ah battery and 40 W photovoltaic panel, charger • Mounting brackets for 48–50 mm poles • Temperature, pressure and relative humidity sensors • GPS • GSM/LTE Data transmission via API, FTP or Finapp Cloud, where mobile coverage is available • SD card for local data storage |
Internal Datalogger Embedded
The data logger is integrated into the probe’s electronic board and is included in both models. All measurements required for in-situ correction of neutron counts—including muons for incoming correction, air pressure, temperature and relative humidity—are provided by the Finapp probe.
All versions of the Finapp are equipped with a datalogger that records:
- Atmospheric pressure
- Internal temperature
- External temperature (optional)
- External relative humidity (optional)
- Auto diagnostic system
- Rain gauge (optional)
- Wind speed (optional)
- GPS (optional)
Measured data is saved locally on an SD card. The stored parameters are:
- Time stamp (UTC)
- Counting of neutrons – according to models
- Counting of muons – according to the models
- Counting of gamma – according to models
- Atmospheric pressure (hPa)
- Internal temperature (°C)
- External temperature (°C) (optional, dependent on modules)
- External humidity (%) (optional, dependent on modules)
- GPS position (optional, dependent on modules)
- Voltage (V)
Output
Soil moisture (% gravimetric or volumetric if soil density is known) averaged and integrated value over a circular area of 5/10 hectares (125/250 meters radius), up to a depth of 50cm in standard conditions.
Installation
About 2m above the ground (detector at about 1.8m from the ground)
Data transmission,
- Through GSM/LTE connection via API and/or access FINAPP cloud and/or FTP
- Via SDI-12
- RS-232 port
- Compatible with the ICT International MFR-Node using SDI-12
- Ethernet
- SDI-12 interface to the LoRaWAN network. The customer is responsible for providing and managing the LoRaWAN gateway required to receive the transmitted data.
Added values
- Real time measurement of soil moisture thanks to muons counting
- Incoming measurement & correction in situ thanks to the patent that correlates neutrons and muons.
- Full configurations: Finapp includes datalogger and all the sensors required for correction: incoming, air pressure, air temperature and air relative humidity.
- Local 8GB SD card: storage and different communication protocols available (Finapp Cloud, API, USB / RS232, SDI-12).
- Remote IoT telemetry: included (SIM included).
- Easy to install: small and compact, sent with anchors. It is enough to set it on a pole.
- Easy to maintain: No consumable or moving parts
- Very low power consumption: 1W/h • Insensitivity to soil salinity, bulk density, texture and roughness surface.
