![]() Furthermore, due to the pure α-decay series of 154Dy (i.e., 154Dy → 150Gd → 146Sm → 142Nd), nucleosynthesis computations aimed to explain the processes that led to the natural isotopic abundances of 146Sm and 142Nd need to take into account the contribution of the decay of its α-unstable progenitors. These models 18, 19, that correlate the observed isotopic abundances to specific nuclear reaction paths, depend on the cross section reactions, which in turn strongly depend on the half-lives of all the nuclides involved. As stated in 16, 17, knowledge on the reaction rates of nuclear reactions such as 154Dy(α, γ) and 154Dy(n,γ), respectively, is useful to test and improve the models used in the prediction of astrophysical p-process reaction rates. ![]() ![]() Through the nuclear reactions 154Dy(α, γ) 158Er 14, 154Dy(γ, α) 150Gd, and 154Dy(γ, 2n) 152Dy 15, this exotic radionuclide contributes to the synthesis of 142Nd, 146Sm, 150Gd, 152Gd, and 158Dy – all nuclides shielded from s- and r-nucleosynthetic processes by their respective isobars. Interestingly, the extinct 154Dy (I α = 100% at E α = 2.87 MeV) 13 is one of the nuclides involved in such p-process reaction networks. Instead, they are produced in a network of photodisintegration and charged particle reactions called p-process 12. The latter is a group of proton-rich isotopes between 74Se and 196Hg that cannot be produced by either slow neutron-capture (s-process) or rapid neutron-capture (r-process) reactions 10, 11. Over the past two decades, there has been a strong effort in the description of the mechanism responsible for the synthesis of p-nuclei. Even though such radionuclides became extinct soon after the formation of the Solar System, it is possible from the analysis of the abundances of their stable decay products to reconstruct the nucleosynthetic processes that occurred millions (or even billions) of years ago, e.g. As a first application of the half-life value determined in this work, the excitation functions for the production of 154Dy in proton-irradiated Ta, Pb, and W targets were re-evaluated, which are now in agreement with theoretical calculations.Įxtinct radionuclides play an essential role in the description and in the reconstruction of recent galactic events, providing as well essential timescale constraints 1, 2, 3, 4. This precise half-life value is useful for the the correct testing and evaluation of p-process nucleosynthetic models using 154Dy as a seed nucleus or as a reaction product, as well as for the safe disposal of irradiated target material from accelerator driven facilities. The half-life value was determined as (1.40 ± 0.08)∙10 6 y, with an uncertainty reduced by a factor of ~ 10 compared to the currently adopted value of (3.0 ± 1.5)∙10 6 y. ![]() The disintegration rate of the radio-lanthanide was measured by means of α-spectrometry. Sector field- and multicollector-inductively coupled plasma mass spectrometry were used to determine the amount of 154Dy retrieved. 154Dy was radiochemically separated from proton-irradiated tantalum samples. Sixty years after the discovery of 154Dy, the half-life of this pure alpha-emitter was re-measured. ![]()
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