Observation of Forbush Decreases and GLE‐74 Recorded During Ground‐Level Neutron Monitoring Survey From Various Sites

Abstract Ground‐level neutron monitors (NMs) are essential tools for monitoring space weather events, including the detection and alerting of ground‐level enhancement (GLE) events. This study presents findings from a neutron monitoring survey using two compact N50L neutron slab‐based subsystems deployed across various field sites in the United Kingdom (UK) with different geomagnetic cutoff rigidities. Data from these N50L subsystems were compared to data from established NM‐64 monitors (Dourbes and Oulu) with similar geomagnetic cutoff rigidities and accessed via the Neutron Monitor Database (NMDB). The cosmic ray (CR) count rates measured by the N50L subsystems closely follow NMDB network trends, while absolute count rates differ due to site altitude, geomagnetic latitude, and local environmental conditions in the immediate vicinity of each detector. Key events observed during the campaign include two Forbush decreases and GLE‐74. The data collected supported the development and deployment of the NM‐2023 design initiative, specifically targeting the site of the first operational 4‐NM‐2023 in the UK. Additionally, data from the N50L subsystems were compared with the University of Surrey's Compact NM setup and the Lancaster University and Mirion Technologies developed NM‐2023, enhancing GLE monitoring capabilities across UK geomagnetic cutoff rigidities. The preliminary measurements from the NM‐2023 prototype conducted at the Warrington site suggest it can achieve performance comparable to the 6‐NM‐64 monitor but with a reduced footprint, volume, mass, and cost, utilizing environmentally friendly, non‐toxic gas‐filled counters. A full 4‐NM‐2023 system has been deployed at Met Office Camborne Observatory near Cornwall, with a 1‐NM‐2023 unit installed at Lancaster University.