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A reduction of the background of about two orders is still needed. The determination of the electron-neutrino mass seems possible but is definitely difficult. In addition two-hole and even three hole states are included into the description of the process. The excitation spectrum in Dy* of one-hole electron states is due to one electron excitation above the Fermi surface (shake-up into bound orbits above the occupied electron states) or into the continuum (shake-off). The difference between the upper end of this deexcitation spectrum and the Q value = 2.8 keV must be the rest mass of the neutrino. The excitation of Dy* can be measured by the total deexcitation energy using a bolometer, which measures photon and Auger electron deexcitations together. The energy of the Q = 2.8 keV value is used to excite 163Dy* and for the total energy, rest mass and kinetic energy, of the emitted neutrino. For electron capture in 163Ho to 163Dy the Q value is very small Q=2.8 keV and thus optimal for the determination of the neutrino mass.Įnergy conservation restricts the capture to 3s1/2 (2 keV binding energy) and 3p1/2 (1.8 keV binding energy) and higher electron orbits in 163Ho. The Q-value, energy difference between the parent and the daughter atom, must be large enough to emit a bound ns1/2 or an np1/2 electron into an excited state or into the continuum. This is the case for electrons in the parent atom in ns1/2 and due to the relativistic lower amplitude in np1/2 orbits. Time: 3:00pm, October 15th (Monday), 2018Įlectron capture in an atom is only possible, if the electron wave function has an overlap with the nucleus. Amand Faessler (University of Tuebingen, Germany)Ĭhairman: Prof. Title: Can the electron-neutrino mass be determined by electron capture?