Solar drift pair bursts in the decameter range

The results of observations of solar decametric drift pair bursts are presented. These observations were carried Out during a Type III burst storm on July 11-21, 2002, with the decameter radio telescope UTR-2, equipped with new back-end facilities. High time and frequency resolution of the back-end allowed Lis to obtain new information about the structure and properties of these bursts. The statistical analysis of more than 700 bursts observed on 13-15 July was performed separately for forward and reverse drift pair bursts. Such an extensive amount of these kind of bursts has never been processed before. It Should be pointed out that forward and reverse drift pair bursts have a set of similar parameters, such as time delay between the burst elements, duration of an element, and instant bandwidth of an element. Nevertheless some of their parameters are different. So, the absolute average Value of frequency drift rate for forward bursts is 0.8 MHz s(-1), while for reverse ones it is 2 MHz s-1. The obtained functional dependencies drift rate vs. frequency and flux density vs. frequency were found to be different from the Current knowledge. We also report about the observation of unusual variants of drift pairs, in particular, of hook bursts and bursts With fine time and frequency structure. A possible mechanism of drift pairs generation is proposed, according to which this emission may originate from the interaction of Langmuir waves with the magnetosonic waves having equal phase and group velocities.