Measurement of the neutron spectrum and dose in the SAA region during strong solar activity episodes by the SAMADHA experiment

The main aim of the SAMADHA (South Atlantic Magnetic Anomaly Dostimetry at High Altitude) project is to monitor the cosmic ray neutron spectrum and dose at very high altitudes in the South Atlantic Anomaly region during the maximum activity of the 25tℎ solar cycle. The experimental setup for this measurement consists of an Extended Bonner Sphere System and a commercial Rem counter. A linear energy transfer spectrometer to measure the electromagnetic part of the extensive air showers, and a high-precision barometer to correct the effect of the atmospheric pressure variations, complete the system. The experiment is operated at the Chacaltaya Cosmic Ray Laboratory in Bolivia, 5270 m above sea level, and can be remotely controlled via an Internet connection. The instruments have been collecting data almost continuously since March 2023, together with a 12NM-64 neutron monitor managed by the local research group. This high energy neutron detector monitors the variations in the flux of cosmic rays which can be used to identify the periods of most intense solar activity. We looked at some important Forbush Decreases that occurred in 2024 and 2025 after strong CMEs from the Sun searching for cross correlations in our data. In this paper, we report on the preliminary comparison between the neutron spectrum and dose measured during two of these episodes with the spectrum and dose measured during the corresponding "quiet sun" periods.