Tridiurnal variations in cosmic-ray intensity |
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Authors: | AH Girgis MF Tolba SA Wahab AM Salem |
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Institution: | Physics Department, Faculty of Science, Ein Shams University, Cairo, Egypt |
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Abstract: | The tridiurnal wave in cosmic-ray intensity expected from a free space anisotropy is theoretically calculated for different cosmic-ray stations which are characterized by different shapes of asymptotic cones of acceptance. The amplitude A and the time of maximum Tmax are given for latitude dependence of the form cosn λ and rigidity dependence of the form , where λ and R are the latitude and rigidity respectively and n, β, R0 are constants. The values of A and Tmax, are calculated for different values of n, β and R0 for each station. The dependence of A and Tmax on the anisotropy parameters is studied for the proper selection of cosmic-ray stations whose data may be used in determining these parameters.Available experimental data were used to find the observed amplitudes of the tridiurnal variations at five stations using power spectrum analysis with hanning applied on the averaged trains. Minimum variance analysis of the theoretical and experimental amplitudes showed that β has a value between 1 and 2, R0 greater than 100 GV and n smaller than 3. |
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