Ultra high energy muons in extensive air showers

Abstract

The design of the modification required to increase the angular resolution of the Haverah Park Magnet Spectrograph is described. It is shown that the reduction in uncertainty of angular measurement achieved by the modification is characterised by a standard deviation of 0.l6 , corresponding to a limit of momentum resolution of 120 GeV/c. The momentum spectra, of muons in EAS derired from the data available at the conclusion of the period of operation of the original spectrograph are presented. These spectra relate to muons falling between 150 m and 600 m from the cores of showers of primary energy within the approximate range 10(^-16) eV to 18(^-18) eV. The preliminary results from the modified spectrograph are also presented but they are shown to be statistically insufficient to be considered as evidence, for or against, the validity of the earlier data. An investigation of the dependence of the momentum spectra on primary energy and shower zenith angle, originally undertaken using data available prior to the end of the period of operation of the Original spectrograph, has been repeated in the light of the improved statistics and revised EAS data. In addition, other checks have been undertaken: (a) on the effect of the accuracy of core location on the momentum spectra, and (b) on the method of deriving the spectra from the data. The data available at the conclusion of the original experiment have also been used, in conjunction with a new theoretical study of the distortion of the muon charge ratio produced by the geomagnetic field, to estimate the height of origin of muons in EAS. It is shown that measurement of this distortion cannot be used to give sufficiently accurate assessment of the height of muon production, to allow comment to be made on the nature of the primary particle or the ultra high energy interactions. Finally, an improved analytical model of EAS is described and the results are compared with those of other workers and observation.