A. Putze et al.: An MCMC technique to sample transport and source parameters of Galactic cosmic rays. II. Fig. 11. Left panel: standard DM model ( r$_{h}$ = 0)—thin-dotted lines are derived using the GAL09 instead of the W03 fragmentation cross-sections. Right panel: modified DM model ( r$_{h}$ = 0). For both panels, shown are the best-fit parame- ters on B/C + $^{10}$Be/$^{9}$Be + $^{26}$Al/$^{27}$Al + $^{36}$Cl/Cl data, as a function of the diffusion slope δ . The latter is varied between 0.1 and 1.0 for model II (blue lines, open and filled squares) and model III (black lines, open and filled circles). From top to bottom, L , K$_{0}$/L , V$_{a}$$_{/}$√$_{K}$$_{0}$$_{, and}$ V$_{c}$ as a function of δ are shown. The bottom panel shows the best χ $^{2}$/ d.o.f for each δ . for the three combinations B/C + Be/B, B/C + Al/Mg, and B/C + Cl/Ar. The trend is similar to that for isotopic ratios: L increases with increasing δ . The main difference is that the increase is sharper for both models II and III. For the former, only a small region around δ ≈ 0 . 2 corresponds to small halo sizes. For the latter, the halo size increases sharply above δ ≳ 0 . 6. For completeness, similar fits were carried out for the modified DM ( r$_{h}$ = 0). However, adding an additional de- gree of freedom only worsens the situation, and the models converge to arbitrarily small or high values of L and r$_{h}$ . Finally, if we fit the combined B/C data, the three isotopic ratios and the three elemental ratios, we do not obtain more constraints than when fitting B/C and the three isotopic ra- tios. This may indicate that the models have difficulties in 14 Combined fit Cl/Cl 36 Al +  27 Al/ 26 Be +  9 Be/ 10 B/C +  0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 L [kpc] 1 10 2 10 III (diff.+conv.+reac.) II (diff.+reac.) = 0] h [r 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1  ] -1 [ kpc Myr /L.50 0 K -1 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 )] )(4- 2 (4- 3 0 /[K a V 0 50 100 ] 1/2  Myr -1  kpc -1 [km s 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1  ]  -1  [ km s c V 0 5 10 15 20 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 /d.o.f 2 1 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 [kpc] h r 0.05 0.1 0.15 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 L [kpc] 1 10 2 10 III (diff.+conv.+reac.) II (diff.+reac.)  0] h [r 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1  ] -1 [ kpc Myr /L.50 0 K -1 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 )] )(4- 2 (4- 3 0 /[K a V 0 50 100 ] 1/2  Myr -1  kpc -1 [km s 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1  ]  -1  [ km s c V 0 5 10 15 20 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 /d.o.f 2 1 10