Asymmetry of L and M β-conversion lines in the thulium atom

We discuss asymmetry of the shape of β-lines of the Tm atom emitted in knockout of an electron from L and M shells in a nuclear transition. (These lines are used for calibration of the spectrometer in the experiment performed at the Institute of Theoretical and Experimental Physics on the search for a nonzero neutrino mass.) The asymmetry arises as the result of excitation of outer electrons to the discrete and continuous spectra. The ''shake-up'' mechanism is dominant up to excitation energies around 150 eV, and its probability is calculated with the Hartree-Fock method