Table 2.

Data for a 4-layered non-absorbing sphere of external radius $r=5$ mm and internal radii 4, 3 and 2 mm.

${\mu }_{s0}$ (${\text{mm}}^{-1}$)	${⟨L_1⟩}_{\mathit{IP}}=2.490833$ mm		${⟨L_2⟩}_{\mathit{IP}}=1.110000$ mm		${⟨L_3⟩}_{\mathit{IP}}=0.395833$ mm		${⟨L_4⟩}_{\mathit{IP}}=0.106667$ mm
	$⟨L_1⟩$ (mm)	${\sigma }_{⟨L_1⟩}$ (mm)	$⟨L_2⟩$ (mm)	${\sigma }_{⟨L_2⟩}$ (mm)	$⟨L_3⟩$ (mm)	${\sigma }_{⟨L_3⟩}$ (mm)	$⟨L_4⟩$ (mm)	${\sigma }_{⟨L_4⟩}$ (mm)
0	2.49068	0.00066	1.10999	0.00053	0.39576	0.00034	0.10699	0.00019
${10}^{-6}$	2.49039	0.00061	1.11017	0.00053	0.39575	0.00033	0.10653	0.00019
${10}^{-5}$	2.49045	0.00052	1.10986	0.00051	0.39594	0.00036	0.10673	0.00019
${10}^{-4}$	2.49136	0.00068	1.10990	0.00052	0.39556	0.00032	0.10667	0.00018
${10}^{-3}$	2.49136	0.00062	1.11052	0.00051	0.39574	0.00033	0.10662	0.00018
${10}^{-2}$	2.49064	0.00055	1.11020	0.00056	0.39567	0.00036	0.10687	0.00015
${10}^{-1}$	2.49165	0.00078	1.10923	0.00053	0.39590	0.00035	0.10687	0.00017
1	2.4904	0.0011	1.10981	0.00093	0.39681	0.00052	0.10682	0.00027

In the first layer, $r\in (4,5)$ mm, $n_1=1.75$ and ${\mu }_s={\mu }_{s0}$; in the second layer, $r\in (3,4)$ mm, $n_1=1.5$ and ${\mu }_s=0$; in the third layer, $r\in (2,3)$ mm, $n_1=1.25$ and ${\mu }_s={\mu }_{s0}$; and in the forth layer $r\in (0,2)$ mm, $n_1=1$ and ${\mu }_s=0$. The refractive index of the external medium is 2. The results of MC simulations for several values of ${\mu }_{s0}$ are shown in table for the partial path length $⟨L_k⟩$ spent in the layers. The values predicted by IP are also shown. The data in table pertain to $N={10}^7$ simulated trajectories. In the supplemental material a version of this table showing the deviation between ${⟨L⟩}_{\mathit{MC}}$ and ${⟨L⟩}_{\mathit{IP}}$ is also reported.