Development and Neutronic Validation of Pelletized Cold and Very Cold Moderators for Pulsed Neutron Sources.

摘要

Intense beams of cold neutrons are produced at several DOE facilities and are used by researchers to study the microscopic structure of materials. Energetic neutrons are produced by a high energy proton beam impacting a target. The fast neutrons are converted to the desired cold neutrons passing through a cryogenic moderator vessel, presently filled with dense cold hydrogen gas. Moderators made from solid methane have demonstrated superior performance to the hydrogen moderators but cannot be implemented on high power sources such as the SNS due to the difficulty of removing heat from the solid blocks of methane.