Time Profiles and Photon Spectra of Solar Hard X-Rays

Abstract

With a spectrometer aboard the ESRO TD-1A satellite, time profiles and photon spectra of solar X-rays have been observed in the energy range above 24 keV. Most of the X-ray bursts studied thus far appear to consist of numerous short-lived spikes with rise and decay times of a few seconds. Such spikes, called ‘Elementary Flare Bursts’ (EFB’s) cluster together in large numbers and constitute the conventional high energy flare. The form of the photon spectra could be determined very accurately and was in all cases of the power-law type. For the August 4, 1972 flare, the photon spectra appear to be combinations of two power-law spectra; for the lower energies the spectral coefficient is smaller than for the higher energies. The transition energy is about 60 keV.KeywordsSolar FlarePhoton SpectrumSolid State DetectorScintillation CrystalPulse Height DistributionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.