A. Putze et al.: An MCMC technique to sample transport and source parameters of Galactic cosmic rays. II. Fig. 10. Shown are the envelopes of 68% CL (shaded areas) and best-fit (thick lines) ratios for the standard DM II ( r$_{h}$ = 0, red) and for model III (standard and modified DM, blue) in the 1D geometry (based on the B/C + $^{10}$Be/$^{9}$Be + $^{26}$Al/$^{27}$Al + $^{36}$Cl/Cl constraint). All quantities are IS. The data are demodulated using the approximate procedure E IS k = E TOA k + Φ. sion/convection/reacceleration). For model II, the size of r$_{h}$ suddenly jumps to ∼ 100 pc. But for δ ≳ 0 . 3, it returns to the pure diffusion regime, r$_{h}$ decreasing abruptly (to a non-vanishing value) and L becoming vanishingly small. In this regime, the thin-disc approximation is no longer valid and nothing can be said about it. For model III, the plateau r$_{h}$ ∼ 100 pc is stable for all δ ≳ 0 . 2. The under- dense bubble also stabilises the value of the halo size L . The way of understanding this trend is as for the stan- dard DM, but now the flux of the radioactive species reads N rad r$_{h}$ (0) ∝ exp( − r$_{h}$$_{/}$√$_{Kγτ}$$_{0}$$_{)}$$_{/}$ √$_{Kγτ}$$_{0}$$_{. The weaker depen-}$ dence of L with δ must be represented by this formula. We underline that for all best-fit configurations leading to r$_{h}$ = 0, the improvement is statistically meaningful com- pared to the case r$_{h}$ = 0. A similar analysis can be carried out using elemental ra- tios instead of isotopic ones. As before, the best-fit values of well-chosen combinations of the transport parameters { K$_{0}$, δ, V$_{c}$, V$_{a}$ } are left unchanged when radioactive species are added to the fit (same values as in Fig. 11). For the standard DM ( r$_{h}$ = 0), the dependence of the diffu- sive halo size L on the diffusion slope δ is shown in Fig. 12, Fig. 12. Best-fit value of the halo size L as a function of δ in standard DM, based on a fit on B/C plus a ratio where a radioactive species is present: B/C+Be/B (black small symbols), B/C+Al/Mg (blue medium-size symbols), and B/C+Cl/Ar (pink large symbols). The dashed lines (square symbols) refer to model II, and the solid lines (circles) refer to model III. 5.2. Isotopic versus elemental measurements 5.2.1. General dependence of L with δ 13 Ek/n (GeV/n) -1 10 1 10 2 10 3 10 B/C 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 IS IMP7-8 Voyager1&2 ACE 97-98 ACE 01-03 AMS-01 HEAO-3 Spacelab-2 CREAM 04 Standard DM II Standard DM III Modified DM III Ek/n (GeV/n) -1 10 1 10 2 10 3 10 Be 9 Be/ 10 0 0.1 0.2 0.3 0.4 0.5 0.6 IS IMP7-8 Balloon #1 Balloon #2 Balloon #3 ISEE-3 Ulysses Voyager1&2 ACE 97-98 ISOMAX Standard DM II Standard DM III Modified DM III Ek/n (GeV/n) -1 10 1 10 2 10 3 10 Al 27 Al/ 26 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 IS Balloon ISEE-3 Voyager1&2 Ulysses ACE 97-98 Standard DM II Standard DM III Modified DM III Ek/n (GeV/n) -1 10 1 10 2 10 3 10 Cl/Cl 36 0 0.05 0.1 0.15 0.2 0.25 IS Ulysses ACE 97-98 Standard DM II Standard DM III Modified DM III 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 L (kpc) 10 2 10 Model III Be/B Al/Mg Cl/Ar Model II Be/B Al/Mg Cl/Ar Combined fit B/C + elemental rad. ratio