Search for a violation of the Pauli exclusion principle for atomic electrons and for nucleons

The Pauli exclusion principle would be violated if three atomic electrons would occupy the atomic K shell or if three protons or three neutrons would be in the nuclear 1s _{1 2} shell. Accelerator mass spectrometry at the Munich accelerator laboratory was used to look for such non-Paulian atoms of ²⁰Ne and ³⁶Ar and for non-Paulian nuclei of ⁵Li with three protons in the nuclear 1s _{1 2} shell. A time-of-flight technique was used for the identification of non-Paulian ²⁰Ne and ⁵Li. In the case of Ar, post-accelerated hydrogen-like ions were looked for. The following limits were obtained: [²⁰Ne] [²⁰Ne] < 2 × 10^-21, [³⁶Ar] [³⁶Ar] < 4 × 10^-17 and [⁵Li] [Li] < 1.3 × 10^-14 for binding energies of ⁵Li between 0 and 40 MeV.