Study of extensive air showers at sea level
Methods of determining the age parameter of air showers of size l0(^4) - 10(^7) particles which trigger the Durham E.A.S, array are discussed. The average age parameter of showers and their dependence on shower size and zenith angle have been studied. The result for the mean age parameter shows consistency with some previous work. Also, the data was used to determine the size spectrum in the range of shower size 2.10(^4) - 2.10(^7) particles in both differential and integral form. The results are then compared with other measurements. Except at very small and large shower size, the spectrum shows a close agreement with previous work assuming all showers obey the Greisen lateral structure function. Possible source directions of cosmic rays have been studied. A study of the arrival directions of showers in galactic coordinates has been carried out and in general indicates an isotropic distribution in arrival directions. In one particular direction an excess of events is observed at the level of 3.4 standard deviations. More experimental data is required to determine whether this is a real source or not. A search for particles that travel faster than light (tachyons) using an unshielded plastic scintillation detector has also been carried out. No evidence for the existence of tachyons has been found.