2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/8043Variations of radiocarbon concentration have been studied in annual rings for the last 350 years (1600-1950)on the basis of our experimental research using methods of spectral analysis. From this interval of time special attention is paid to the so-called period of the Maunder minimum (1645-1715) of solar activity. In the experimental series of corresponding period two types of periodicity are revealed: 20 year and 8 year.5 pages, 3 figuresAstrophysicstext