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. Space weather events pose a great risk to critical infrastructures such as radio communication, satellite operations, electrical power grids, and aviation technology. The UK has registered severe space weather events as a potential risk to critical infrastructure. The UK designed and built a new standard ground‐level neutron monitor called NM‐2023 for severe space weather radiation assessment. A 4‐NM‐2023 matches the performance of a 6‐NM‐64 design but with a reduced footprint, volume, mass, and cost, utilizing environmentally friendly, non‐toxic gas‐filled counters. We present neutron monitoring survey results from N50L neutron slab‐based subsystems (from now on referred as N50L subsystems) deployed across several UK sites and the University of Surrey's Compact Neutron Monitor (CNM). The N50L subsystems and CNM provide data that have similar trends to the data from DRBS and Oulu, despite both being significantly smaller. The count rate measurements are influenced by altitude, latitude, and objects around the NM. The N50L subsystems, 2‐NM‐2023, DRBS, and Oulu were able to observe the Forbush decrease which occurred over the 2024 spring. However, only Oulu registered sufficient cosmic ray counts to be classified as GLE‐74, classified as a weak GLE. Forbush decreases and GLE‐74 observed over the Northern Hemisphere in Spring 2024 Cosmic ray count rate trends from N50L subsystems match Compact Neutron Monitor (CNM) and NM‐64 monitors at similar geomagnetic cutoff rigidities The 4‐NM‐2023 matches 6‐NM‐64 count rates with a smaller, lighter, lower‐cost design using non‐toxic gas‐filled counters