Can Cosmic Rays Neutron Sensors provide valuable data about space weather events?

Cosmic Rays Neutron Sensing (CRNS) is a method to derive the amount of water in the environment by the measurement of neutron albedo in the proximity of the soil. The signal is strongly affected by the incoming cosmic rays modulation, requiring a continuous real-time correction that is typically achieved by taking as a reference the observations provided by the Neutron-Monitor DataBase (NMDB). Using the incoming flux of muons as a reference has been proposed as an alternative method of correction by Finapp, whose CRNS detector is capable of contextually measuring both neutrons and muons.

What is noise for some can be signal for others, which leads to increasing collaboration between the CRNS and the Space Weather communities. While CRNS devices cannot provide a level of accuracy and resolution comparable to dedicated neutron monitors, they would compensate with the number of deployed detectors. Being low-cost, easy to install and maintain, their use is spreading fast for various purposes, from agriculture to environmental monitoring. This can be seen as a low-cost world-wide diffuse observatory, potentially with a much higher spatial density than the NMDB and spontaneously growing.

Assessing how neutron and muon count rates measured by these devices are affected by space weather events, like Forbush decreases or Ground-Level Enhancements (GLE), could increase the understanding and monitoring of such events by providing a mapping of their impact on the Earth surface. If the CRNS station is equipped with a Finapp detector, the contextual detection of muons can provide additional information.

In this presentation we will analyze how a small set of Finapp CRNS probes, located in different locations of Earth, responded to some major events of Furbush decrease or GLE, in the neutron and muon count rate signals. The set includes, among others, two probes located in NMDB sites (OULU and JUNG) and a probe installed in Svalbard. This aims to be an example of the potential interest of CRNS for Space Weather investigation. A large database of collected data may be already available and underused.

Acknowledgement

We acknowledge the NMDB database (www.nmdb.eu), founded under the European Union's FP7 programme (contract no. 213007) for providing data. Jungfraujoch neutron monitor data were kindly provided by the Physikalisches Institut, University of Bern, Switzerland. Oulu neutron monitor data were kindly provided by the Sodankyla Geophysical Observatory (https://cosmicrays.oulu.fi). CaLMa neutron monitor data were kindly provided by the Space Research Group (SRG-UAH), University of Alcala, Spain.