Figure 3.

(a) A primary beam track, (b) the chord length distribution of primary tracks normalized by the maximum length, f(L_Ch,N), (c) $D_{\mathit{Sph},1}^{\delta ,1}$ as a function of impact parameter, b and (d) CDDF(b) of impact parameter are plotted for spherical target volumes. The results are presented for ³He beam and V_Sph1 (d_Sph=0.545 μm) in (a,b) and V_Sph3 (d_Sph=2.210 μm) in (c,d). The blue line in figure 4(c) shows the slope on linear scale $(D_{Sph,1}^{\delta ,1}(\mathrm{\text{Gy}})=\mathit{constant}+\mathit{slope}\times b)$ which fits to a negative slope; 0.1504 – 0.00184×b Gy. Similarly, the slope on log-log scale plotted as a red line in figure 3(c), is positive valued; $\mathit{Log}(D_{\mathit{Sph},1}^{\delta ,1})=\mathit{constant}+\mathit{slope}\times \mathit{Log}(b)=-1.2057+0.05698\times \mathit{Log}(b)$.