Which characteristic should a material used for a reflector possess?

In the context of nuclear reactors, reflectors are materials placed around the reactor core to reflect neutrons back into the core, thereby enhancing the likelihood of fission events and improving the overall efficiency of the reactor. The ideal characteristic for a material used as a reflector is a high scattering cross-section.

A high scattering cross-section means that when neutrons encounter the reflector material, they are more likely to interact with it by scattering. This scattering process redirects neutrons back towards the core, increasing the chances that they will collide with fissile material and contribute to the sustained chain reactions that are critical in nuclear fission processes.

Materials with high scattering properties are typically metals like bismuth or lead, or certain types of graphitic materials, as they effectively bounce neutrons back into the core. The ability to scatter neutrons is crucial for maintaining an efficient nuclear reaction.

In contrast, materials with low scattering cross-sections would not effectively redirect neutrons, thus hindering the reactor's performance. High capture cross-sections would mean that the material absorbs neutrons rather than reflecting them, which would detract from the intended function of a reflector. High density alone does not guarantee effective reflection, as it's the interaction mechanism that is critical for performance. Therefore,