Power spectrum analysis of LMSU (Lomonosov Moscow State University) nuclear decay-rate data: Further indication of r-mode oscillations in an inner solar tachocline

► Measurements of the 90Sr-90Y decay process show a strong annual variation. ► They also show an oscillation attributable to internal solar rotation. ► Additional low-frequency oscillations are indicative of internal r-mode oscillations. ► These oscillations apparently occur in an inner tachocline. ► This tachocline separates the radiative zone from a slowly rotating core.