Figure 5.

Monte Carlo (MC) simulation of fluence rate distribution by a circular beam of radius (a) 0.4 cm and (b) 8 cm incident on a semi-infinite liquid surface as a function of depth (d) for μ_a = 0.09, 0.18, and 0.58 cm⁻¹ and μ_s’ = 0.2 cm⁻¹. Fits of exponential forms are shown along with the MC data. The exponential form of e^−μ_ad fits the simulation well up to a depth of 0.4 cm, while overestimating φ/φ₀ at larger depths. Broad-beam simulations agree with the simple exponential form up to a depth of 1.3 cm.