Case of WIM. Left panel: SNR age t_esc (solid lines, left axis) and radius R_esc (dashed lines, right axis) at the time of CR escape as a function of CR energy. Right panel: grammage (left axis) accumulated in a region of ∼100 pc around the source as a function of CR energy as deduced from the estimated residence time t_res (right axis) in that region. The grammage accumulated during CR Galactic propagation as estimated by Ptuskin et al. (2009) (X_P09, olive line) and by Evoli et al. (2019) (X_E19, gray line) is also shown. The cyan curve is computed by assuming that particles of all energies escape at an SNR radius of 20 pc, as assumed by D’Angelo et al. (2016). Different colors are used for different values of the hydrogen ionization fraction f and helium-to-hydrogen ratio χ. The parameters of the WIM are listed in Table 1.