Hubert G. auteur aut IRD Herbert Gaëlle auteur aut IRD Tilhac A. auteur aut IRD Rey R. auteur aut IRD Bourlès Bernard auteur aut IRD text journalArticle eng text/pdf born digital access This paper presents the operation of a neutron spectrometer onboard the R/V La Thalassa during the PIRATA (Prediction and Research Moored Array in the Tropical Atlantic) oceanographic cruises in the equatorial Atlantic. The cruises took place from February to April in 2019 and 2020. We analyze cosmic ray-induced neutrons measured by the spectrometer, accounting for various physical factors influencing neutron detection, including environmental and systematic effects primarily driven by atmospheric pressure and water vapor content variations. Additionally, the study incorporates the influence of short-term fluctuations in primary cosmic rays to investigate the geomagnetic cutoff rigidity dependence. Detailed analyses of count rates, fluxes, and neutron spectra are provided, facilitating cross-comparison of radiation fields. The mobile neutron spectrometer enables latitude-dependent surveys, assessing the impact of geomagnetic cutoff rigidity on neutron spectra. Equivalent 3NM64 count rates were derived from PIRATA measurements and compared with previous results. specialized Cosmic ray Atmospheric radiation environment Neutron spectrometer PIRATA oceanographic cruises ATLANTIQUE ZONE TROPICALE 020 021 030 278 106690 [12 p.] 2026 1364-6826 https://www.documentation.ird.fr/hor/fdi:010095863 10.1016/j.jastp.2025.106690 1364-6826 [F B010095863] https://www.documentation.ird.fr/hor/fdi:010095863 https://www.documentation.ird.fr/intranet/publi/2026-01/010095863.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2026-01-14 2026-01-14 fdi:010095863 fre