Extracting the ground level enhancement event of February 1956 from Legacy cosmic ray recordings

Abstract

Early continuous recordings of cosmic rays, as measured with Carnegie Type C Ionization Chambers, were made on rolls of photographic paper. This paper describes the extraction of the ionization data of a ground level enhancement (GLE) event from the ionization chamber recordings of three stations, viz.: Godhavn, Cheltenham, and Christchurch. The extracted ionization data was then converted to percentage increase above background cosmic ray levels and compared to existing neutron monitor data. The recordings share common attributes, such as a sharp rise to a peak which tapers off more slowly. This trend, seen in all three data sets, is consistent with the neutron monitor data