The “Days on Diffraction” are annually organized in the beginning of summer by the St. Petersburg State University, St. Petersburg Department of Steklov Mathematical Institute (PDMI) of the Russian Academy of Sciences, and Euler International Mathematical Institute.
The “Day on Diffraction” have been held since late 1960-s. Originally these were one-day seminars summing up the results of the famous Leningrad Diffraction Theory School headed by V.A. Fock and V.I. Smirnov. The works of V.I. Smirnov and S.L. Sobolev on functionally-invariant solutions of wave equation in the beginning of 30-s, the method of partial separation of variables suggested by V.I. Smirnov in 1937, widely known works of V.A. Fock on diffraction of radio-waves around the surface of the Earth of 40-s laid the cornerstone of Leningrad – St. Petersburg school. The main body of the diffraction school in 60s – 70s was constituted by the students of G.I. Petrashen' who proceed with and developed the subjects of diffraction after the World War II.
The idea of organizing annual seminars on diffraction theory and wave propagation has arisen in 1968, and the first one was held in June 1968. The next day after the Seminar its participants, which were young in those times, went to Komarovo on the bank of the Gulf of Finland, played volleyball, football on the beach, drank tea. All the sessions since have always ended with friendly picnic parties with a camp fire and traditional Russian games. Year by year the Soviet scientists from other cities began to participate and the “Day on Diffraction” became an All Union Seminar. Since 1986 the event occupied two days: the first was organized in Leningrad, the second was at the faculty of Physics in Peterhoff. Within the last decade “Day on Diffraction” (recently “Days on Diffraction”) became international and occupies four (five, since 2011) days with the number of participants exceeding one hundred. Conference's web-history available since 1996.
Reference: V.M. Babich, A.P. Kiselev, “Days on Diffraction,” Successor of all-USSR symposia and schools on diffraction theory, In Russian, English translation: Journal of Math. Sciences, 2011, Vol. 175, Issue 6, pp. 621–622.