A conclusion could be drawn from both the XCOM and experimental results are that
“foam + liquid” samples do have larger mass attenuation coefficients than bulk samples.
Since the mass attenuation coefficients already consider the density factor, definitely we can
make a conclusion that the “foam + liquid” samples have better attenuation while having the
benefit of weight saving. This point is illustrated in Figure 4.10, which shows a plot of the
experimental results for bulk material and “10 PPI foam + water” samples.