Research Facility Center for Science and Technology, University of Tsukuba, Tsukuba, Japan.
Science. 2012 Mar 30;335(6076):1614-7. doi: 10.1126/science.1215510.
The extinct p-process nuclide (146)Sm serves as an astrophysical and geochemical chronometer through measurements of isotopic anomalies of its α-decay daughter (142)Nd. Based on analyses of (146)Sm/(147)Sm α-activity and atom ratios, we determined the half-life of (146)Sm to be 68 ± 7 (1σ) million years, which is shorter than the currently used value of 103 ± 5 million years. This half-life value implies a higher initial (146)Sm abundance in the early solar system, ((146)Sm/(144)Sm)(0) = 0.0094 ± 0.0005 (2σ), than previously estimated. Terrestrial, lunar, and martian planetary silicate mantle differentiation events dated with (146)Sm-(142)Nd converge to a shorter time span and in general to earlier times, due to the combined effect of the new (146)Sm half-life and ((146)Sm/(144)Sm)(0) values.
已灭绝的 p 过程核素 (146)Sm 通过测量其 α 衰变子体 (142)Nd 的同位素异常，可用作天体物理和地球化学时标。基于 (146)Sm/(147)Sm α 活度和原子比的分析，我们确定 (146)Sm 的半衰期为 68 ± 7 (1σ)百万年，短于目前使用的 103 ± 5 百万年。该半衰期值意味着早期太阳系中初始 (146)Sm 丰度较高，((146)Sm/(144)Sm)(0) = 0.0094 ± 0.0005 (2σ)，高于之前的估计。由于新的 (146)Sm 半衰期和 ((146)Sm/(144)Sm)(0) 值的综合影响，用 (146)Sm-(142)Nd 测定的地球、月球和火星行星硅酸盐地幔分异事件集中在较短的时间跨度内，总体上时间更早。
