Muon Flux Variations Measured by Low-Cost Portable Cosmic Ray Detectors and Their Correlation With Space Weather Activity

We present a comparison of the measured cosmic ray (CR) muon fluxes from two identical portable low-cost detectors at different geolocations and their sensitivity to space weather events in real time. The first detector is installed at Mount Wilson Observatory, CA, USA (geomagnetic cutoff rigidity Rc similar to 4.88 GV), and the second detector is running on the downtown campus of Georgia State University in Atlanta, GA, USA (Rc similar to 3.65 GV). The variation of the detected muon fluxes is compared to the changes in the interplanetary solar wind parameters at the L1 Lagrange point and geomagnetic indexes. In particular, we have investigated the muon flux behavior during three major interplanetary shock events and geomagnetic disturbances that occurred during July and August of 2022. To validate the interpretation of the measured muon signals, we compare the muon fluxes to the measurement from the Oulu neutron monitor (NM, Rc similar to 0.8 GV). The results of this analysis show that the muon detector installed at Mount Wilson Observatory demonstrates a stronger correlation with a high-latitude NM. Both detectors typically observe a muon flux decrease during the arrival of interplanetary shocks and geomagnetic storms. Interestingly, the decrease could be observed several hours before the onset of the first considered interplanetary shocks at L1 at 2022-07-23 02:28:00 UT driven by the high-speed Coronal Mass Ejection and related geomagnetic storm at 2022-07-23 03:59:00 UT. This effort represents an initial step toward establishing a global network of portable low-cost CR muon detectors for monitoring the sensitivity of muon flux changes to space and terrestrial weather parameters. A pair of identical, low-cost, and portable cosmic ray (CR) muon detectors is set up over 3,500 km apart for an exploratory study of monitoring space and terrestrial weather in real time at a global scale. One detector is installed on Mount Wilson, California and the other is in downtown Atlanta, Georgia. To validate the interpretation of the measured muon signals, the muon fluxes are compared to the well-known neutron flux measurement from the Oulu neutron station in Finland. The results of this analysis show that the CR flux from both muon detectors typically decreases during geomagnetic storm events and that the muon detector installed on Mount Wilson is significantly correlated with the Oulu neutron monitor. Although this is yet an initial effort of building a global network of CR muon detectors for monitoring the space and earth weather in real time, the study provides evidence that muon network detection efficiency can be sufficient for a diagnostic of the major geoeffective space weather events. A global network of portable muon detectors is under development for monitoring the dynamic changes of the space and terrestrial weatherA comparison of the measured cosmic ray (CR) muon fluxes from two identical detectors at different geolocations in real-time is carried outA correlation study between the muon data and the neutron measurement at Oulu CR station in Finland is presented in this paper