Monte Carlo method was used to study the
characteristics of neutron interactions with cells underneath a water medium
layer with varying thickness. The following results were obtained. (1) The
fractions of neutron interaction with <sup>1</sup>H, <sup>12</sup>C, <sup>14</sup>N
and <sup>16</sup>O nuclei in the cell layer were studied. The fraction with <sup>1</sup>H
increased with increasing medium thickness, while decreased for <sup>12</sup>C,
<sup>14</sup>N and <sup>16</sup>O nuclei. The bulges in the interaction
fractions with <sup>12</sup>C, <sup>14</sup>N and <sup>16</sup>O nuclei were
explained by the resonance spikes in the interaction cross-section data. The
interaction fraction decreased in the order: <sup>1</sup>H > <sup>16</sup>O
> <sup>12</sup>C > <sup>14</sup>N. (2) In general, as the medium
thickness increased, the number of “interacting neutrons” which exited the
medium and then further interacted with the cell layer increased. (3) The area
under the angular distributions for “interacting neutrons” decreased with
increasing incident neutron energy. Such results would be useful for deciphering
the reasons behind discrepancies among existing results in the literature
