New Hafnium Isotope,Hf182

182Hf-182W isotope systematics of chondrites, eucrites, and martian meteorites: Chronology of core formation and early mantle differentiation in Vesta and Mars

“…Quitté et al (2003) reported an initial 182 Hf/ 180 Hf ratios of the solar system of (1.6 Ϯ 0.3) ϫ 10 Ϫ4 , which was later corrected to (1.4 Ϯ 0.2) ϫ 10 Ϫ4 by . This value is significantly higher than the solar system initial 182 Hf/ 180 Hf inferred above, and a possible reason for this discrepancy may be the uncertainty of the half-life of 182 Hf that is Ϯ 2 Myr for a half-life of 9 Myr (Wing et al, 1961). Alternatively, formation of the solar system, or more accurately the last nucleosynthetic event that produced 182 Hf, may have occurred more than 4567.2 Ϯ 0.6 Ma ago.…”

“…The time difference between Hf/W fractionation in any two samples or reservoirs can be calculated from their initial 182 Hf/ 180 Hf ratios as determined from the slope of an isochron in a plot of 182 (Wing et al, 1961). In order to convert the relative timescale obtained in this manner to absolute ages, determination of the 182 Hf/ 180 Hf ratio at a well-defined point in time is needed.…”

The distribution of short-lived radioisotopes in the early solar system and the chronology of asteroid accretion, differentiation, and secondary mineralization

“…For 53 Mn, t 1/2 = 3.7 ± 0.4 Ma reported by Honda and Imamura (1971) is conventionally chosen, and we adhere to that choice, although somewhat higher values of 3.9 ± 0.6 and 3.85 ± 0.4 Ma were reported by Wö lfle et al (1972) and Heimann et al (1974), respectively. For 182 Hf, t 1/2 = 8.90 ± 0.09 Ma reported by Vockenhuber et al (2004) is in exact agreement with a weighted average including earlier determinations by Naumann and Michel (1961) and Wing et al (1961). We examine the chronology of differentiated asteroids by applying these three short-lived chronometers in combination with 207 Pb/ 206 Pb ages to provide an overview of asteroid evolution during the first $10 Ma of solar system history.…”

JENDL-4.0: A New Library for Nuclear Science and Engineering

“…The 1=v-shaped capture cross sections of 181;182 Hf were normalized to measured thermal cross sections, because no RRPs were available for the two isotopes. As for 181 Hfðn; Þ, there exist only two experimental thermal cross sections, 191,192) and the present evaluation is based on the latest data. 191) More experimental data would be needed to improve the reliability of the production cross section of the long-lived 182 …”