Abstract
Developing mass spectrometric techniques, dataing methods using extinct nuclides have been applied to many meteorites to understand cosmochemical processes. In the dating, a half life is a very important value for obtaining an accurate age. Almost half lives values of extinct radionuclides were detemined by 1960s, since then it was a few case that their half lives were examined. Recently we measured a half life of 53Mn. We will review half lives of extinct radionuclides and present our half life value of 53Mn.
