Study of extensive air showers at sea level

Abstract

The zenith angle distribution of EAS over the size range 10(^4) -1.4.10(^6) particles at sea level has been studied. Representing the zenith angle distribution by 1(θ) = I(O)cos(^n)θ it is found that n = 8.4 (^+) (_-) 0.3 over the size range 5.10(^10) 1.4.10(^6) particles. For the smallest sizes studied 10(^4) < 5.10(^4) the measurements suggest n decreases to 5.1 (^+)(_-)1.3,The design and performance of a prototype plastic scintillation counter of area 80 cm 50 cm = 0.4 m(^2) is described. The response of the counter is such that it gives a single particle peak well resolved from the noise when its response to the global cosmic ray flux is displayed on a pulse height analyser. Two such counters of this type were used as local electron density detectors to register the arrival of extensive air showers in a tachyon search experiment. The tachyon search experiment showed evidence that tachyons may be associated with extensive air showers of local electron density > 25m(^-2) The evidence is based on the observation of an excess of ionising events (4.4 standard deviations above the background) occurring in the 85-95 us time domain before the arrival of the main shower front at sea level.