New lower limits on the lifetime of heavy neutrino radiative decay

The data collected during the 2006 total solar eclipse are analyzed in the search for signals produced by a hypothetical radiative decay of heavy neutrinos. In the absence of the expected light pattern, we extract lower limits for the heavy neutrino components proper lifetime. The present analysis restricts to the direct hierarchy hypothesis (m3 ≫ m2 > m1). The quality of the data in terms of reached sensitivity suggests that those are the best limits obtainable using this technique.