Shape of the power spectrum of cosmic ray at ground level up to 7 x 10 super(-) super(3) Hz

The power spectral density of cosmic-ray fluctuations observed at ground level during the years 1966-1968 has been calculated. To obtain the correct shape of the spectrum, the fast Fourier transform method with a triangular data window was used, and corrections were made for uncorrelated errors and aliasing effects. When ignoring the Earth rotation peaks, the spectral index alpha , for a sample of polar, middle latitude, and equatorial stations, is [perspective to] -1.96 in the frequency range 3 x 10 super(-) super(7) -10 super(-) super(4) Hz. A possible break around 10 super(-) super(5) Hz, if existing, would be, on the whole, barely significant, as alpha would change from [perspective to] -1.96 to -2.10. There are indications that, from 10 super(-) super(4) Hz to 7 x 10 super(-) super(3) Hz, the spectrum continues with alpha [perspective to] -2.