Shot-noise character of hard X-ray emission in a solar flare

Power spectrum analysis of the hard X-ray flux of a -B flare, detected on 1974 July 6 at 10/sup h/37/sup m/ UT during a balloon flight, has shown that the intensity is not consistent with nonstationary Poisson statistics for the distribution of detected photons, i.e., correlations are present in the frequency range 0.5--50 Hz. The measured power spectrum, in fact, may be consistently interpreted as being due to a nonstationary shot-noise process, suggesting a model for the emission where elementary spikes having decay times of 120 ms are superposed at a variable rate, thus reproducing the time profile of the burst