![]() Some points to be made about the equation:ġ) The nuclide that decays is the one on the left-hand side of the equation.Ģ) The order of the nuclides on the right-hand side can be in any order.ģ) The way it is written above is the usual way.Ĥ) The mass number and atomic number of the neutrino are zero.ĥ) The neutrino symbol is the Greek letter "nu."Įxample #2: Here is another example of a positron decay equation: These points present a simplified view of what positron decay actually is:ġ) Something inside the nucleus of an atom breaks down, which causes a proton to become a neutron.Ģ) It emits a positron and a neutrino which go zooming off into space.ģ) The atomic number goes DOWN by one and mass number remains unchanged. Positron decay is like a mirror image of beta decay. Fitting core-level edges, either in electron-capture spectroscopy or in x-ray absorption spectroscopy, by a single resonance thus leads to an underestimation of the core hole lifetime.ChemTeam: Writing Positron and Electron Capture Equations Writing Positron Decay and Electron Capture Equations Alpha Decay & Beta Decay Neutron Emission and Capture Gamma Decay Proton Emission and Capture Spontaneous Fission Radioactivity MenuĪ Brief Tutorial About Writing Nuclear Symbols ![]() The multiplet broadening and Auger shake-up of the main core-level edges do, however, change the apparent linewidth and accompanying lifetime of these edges. As the end point of the spectrum is affected most by the neutrino mass, these additional states do not directly influence the statistics for determining the neutrino mass. The additional structures due to Auger decay are, although clearly visible, relatively weak compared to the single core hole states and are incidentally far away from the end-point region of the spectrum. Multiplets crucially change the appearance of the resonances on a Rydberg energy scale. Many-body Coulomb interactions lead to the formation of multiplets and to additional peaks corresponding to multiple core holes created via Auger decay. The electronic relaxation after an electron-capture event due to the modified nuclear potential leads to a mixing of different edges, but, due to conservation of angular momentum of each scattered electron, no additional structures emerge. We find that relativistic interactions beyond the Dirac equation lead to only minor shifts of the spectral peaks. Our comparison to experimental electron-capture data critically tests the accuracy of these theories. We use theoretical methods developed and extensively used for the calculation of core level spectroscopy on correlated electron materials. Our current level of theory includes all intra-atomic decay channels and many-body interactions on a basis of fully relativistic bound orbitals. ![]() Here we present an ab initio calculation of the electron-capture spectrum of Ho 163, i.e., the Ho 163 decay rate as a function of the energy distribution between the Dy 163 daughter atom and the neutrino. The determination of the electron neutrino mass by electron capture in Ho 163 relies on a precise understanding of the deexcitation of a core hole after an electron-capture event.
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