An update on the UK ground level neutron monitor implementation phase.

The global network of neutron monitors comprises predominantly of the monitor standardised by Carmichael in 1964, the NM-64.  The design of these existing monitors and their instrumentation have changed very little over the last sixty years.  For example, their neutron detectors rely on gas filled proportional counters that are either filled with highly toxic boron trifluoride (BF₃) or helium-3 (³He) in an arrangement not optimised for this detector type.  We have designed a new neutron monitor optimised for fully modernised, 1” diameter, gas-filled ³He detectors.  Our new design is optimised for cost savings, compactness and efficient use of ³He.  Benchmarked against a 6-NM-64, our design has a 71% smaller footprint, 83% smaller volume, and is 55% lighter.  It is estimated to be ~50% cheaper, excluding cost reductions associated with the shipping, installation, housing, maintenance and operation of a more compact instrument.  It is suited for unattended operation in relatively remote locations and designed to produce comparable results to a 6-counter NM-64 typically used in the existing global network.  We provide a progress update and latest validation results relating to the implementation of the new design at the UK Metrological Office’s Camborne observatory near Cornwall.  Funded by UK Research & Innovation (UKRI), this research is part of the Space Weather Instrumentation, Measurement, Modelling and Risk (SWIMMR) programme.