The energy-loss spectrum of extensive air showers recorded by the Haverah Park 500 m array

Abstract

An integral energy-loss spectrum of air showers is presented for each of four zenith angle intervals 0 degrees -20 degrees , 20 degrees -30 degrees on 2950 showers selected from over 30 000 recorded by the Haverah Park 500m air shower array in a running time of 6.4*107s. Here the energy loss of a shower is defined as the energy dissipated by the shower in an annulus of water 1.2 m thick in the range of distance 100 m to 1000 m from the shower axis. The energy-loss spectra for the four zenith angle intervals may be represented by power laws of exponent -1.94+or-0.06, -2.10+or-0.06, -2.26+or-0.09 and -2.22+or-0.10, respectively, over the energy-loss range 1014.6-1015.6 eV. This corresponds, in so far as the relation between energy loss and primary energy has been established to primary energies in the range 1017-1018 ev. The zenith angle distribution of the selected showers is consistent with exponential atmospheric absorption with an absorption length of 150+or-5 g cm-2. The results show no indication of a change in the slope of the primary cosmic ray energy spectrum within the energy range 1017- 1018 ev.