| The aim of the present work was to study the following aspects of EAS : i) Detection and determination of air showers parameters by measuring the particle densities. ii) Measurement of inclination of shower axis by recording arrival time distribution of shower front particles. iii) Measurement of FWHM of pulses photographed and study of Linsley effect. iv) Characteristics of Cherenkov radiation from air showers. v) Characteristics of low frequency (120 KHz) radio signal from showers.;Electromagnetic radiation both optical Cherenkov radiation and radio frequency (120 KHz) as well as pulses associated with extensive air showers (EAS) of energy ranging from 1.5 X 1015ev to 2.1 X 10 18ev and zenith angles 15° < 0 < 60° were selected for the present analysis.;The lateral distribution of Cherenkov pulses were assumed to have an exponential form fitted with an exponential law with an exponent reflecting the depth of shower maxima (Xm).;The variation of rise time (FWHM) with core distance (R) was studied from pulses photographed.;The experiments based on the above investigations were carried out at the Cosmic Ray Research Laboratory, Gauhati University, India, since September 91 to March, 1994.;The high field associated with low frequency radio signal (120KHz) and its variation with primary energy (Ep), core distance and zenith angle (0) were observed.;The thesis consists of the following five chapters:;1. INTRODUCTION - This chapter contains a brief history of cosmic rays, its composition, development of EAS, emission of electromagnetic radiation from EAS, a brief introduction to the present work including review of the earlier works and aim of the experiment.;2. THEORY - This chapter mainly reviews the theories and numerical calculations.;3. EXPERIMENTAL SET-UP - This chapter describes in detail the instrumentation developed, working principle, calibration etc.;4. DATA COLLECTION AND ANALYSIS - This chapter includes data collection, selection of data for required energy ranges, graphs, data fitting and comparative study.;5. DISCUSSION AND CONCLUSION - This chapter contains the outcome of data analysis, problem and prospects of the whole work as well as scope of future work and conclusions drawn.;From the experimental study, the following inferences were drawn : i) The rise time of the pulses is an increasing function of core distance (R) and a decreasing function of particle density and the distribution of FWHM with R is almost linear upto about 100m. |
