Studies on radio emission at lower frequencies from vertical and inclined large EAS

Abstract

The title of the thesis is quotStudies on radio emission at lower frequencies from vertical and inclined large EASquot. The frequencies selected for the study are 120 KHz and 400 KHz. The experimental works were performed at the Cosmic Ray Research Laboratory, Department of Physics, Gauhati University since February 1991 to March 1994. The thesis consists of five chapters as stated below : Chapter 1 : Introduction This chapter contains a brief history of cosmic rays and its composition. development of EAS in the atmosphere, emission of electromagnetic radiation from EAS etc. The aims of the present studies are also mentioned in this chapter. The present study presented in the thesis includes the following aspects : I. Determination of shower parameters, viz. core location (x0, y0), shower size (N) and age parameter (S) by measuring the particle densities of the showers. II. Determination of arrival directions of primary particles by measuring arrival time distribution of shower front particles. III. Study of the lateral distribution of the field strength and some other characteristics of the radio emission at lower frequencies from vertical and inclined EAS. IV. Study on production mechanism of radio emission at lower frequencies. V. Study of dependence of radio field intensity on depth of shower maximum. VI. Study of polarisation of radio signals. Chapter 2 : Theories A brief of the existing theories and calculations are presented in this chapter. Theories on lateral distribution of shower front charged particles as well as electromagnetic radiation, determination of inclination of shower axes, production mechanism of radio waves at lower frequencies from EAS, dependence of radio signals on depth of shower maximum etc. are the main contents of this chapter. Chapter 3 : The Experimental set-up Details of the experimental arrangements, design. fabrication and installation of various units, testing and calibration of the set-up have been discussed in this chapter. The study is based on the ground level observations. To...