Project Details
Projekt
Ab initio Prediction of the 163Ho Electron Capture Spectrum
Applicant
Professor Dr. Maurits Haverkort
Subject Area
Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
Theoretical Condensed Matter Physics
Theoretical Condensed Matter Physics
Term
from 2018 to 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 254114301
Within this workgroup, we will ab initio predict the calorimetric electron capture spectra of 163Ho. From the particle physics point of view, the weak interaction of an electron with a proton leading to the creation of a neutron and an electron neutrino is theoretically straightforward. In a neutral atom, when this same interaction occurs, more complex processes will accompany the electron capture by the nucleus. Electrons in an atom are not independent identities and due to strong Coulomb forces, all electrons react once one electron is captured. The calorimetrically measured spectrum of Ho is thus not given by just 7 Lorentzian shaped peaks originating from capture events from the 3s to 6s and 3p1/2 to 5p1/2 shell respectively, but several additional shake-up and shake-off structures with an involved multiplet structure emerge. The theoretical description of the full spectrum requires one to have knowledge about the Green’s function propagators describing the time evolution of a Dy atom with the electron multi-configurational many body wave-function corresponding to the ground-state of Ho with one additional core hole. The time evolution involves fluorescence and Auger decays into bound and continuum states. These decays produce the tails of the spectrum and ultimately create the end-point of the spectrum that is influenced most by the mass of the neutrino.Using a combination of numerical methods as used in quantum chemistry (configuration interaction) and solid state physics (Green’s functions and renormalization group) we aim to achieve a numerical accuracy able to predict the mulitplet governed spectra of the core level decay with unprecedented precision. In order to achieve this we will include all possible local multiplets (shake-up and shake-down) as well as Auger and fluorescence yield decay of the excitations. We furthermore will consider the interaction of the local Ho 4f states with the electronic continuum of the host metal. We will develop the needed numerical methods to handle the many body correlations of both the ground-state as well as the excited states with sub-electron volt accuracy. We will furthermore provide an error estimate of the calculations indicating the maximal difference between the physical reality and calculated spectra.These calculations will firstly provide a detailed understanding of the electron capture resonances and their structure. Secondly, these calculations will provide information how much the end-point region is influenced by mulitplet excitations, extended fine-structure in the spectra due to multiple scattering events of Auger electrons in the host material and selection rules in the decay process related to the alignment of the magnetic moment of the 163Ho 4f shell and the 163Ho nucleus. The final aim is to provide a detailed understanding of the 163Ho electron capture spectrum needed for the accurate determination of the neutrino mass.
DFG Programme
Research Units
