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Non-static surfaces in MCNPX: The chopper extension

by Kyle B Grammer, Franz X Gallmeier, Erik B Iverson
Publication Type
Conference Paper
Journal Name
Journal of Neutron Research
Publication Date
Page Numbers
191 to 198
Conference Name
International Collaboration on Advanced Neutron Sources
Conference Location
Chattanooga, Tennessee, United States of America
Conference Sponsor
Conference Date

Rotating objects, such as choppers, are common components of a neutron beamline, and the motion of these components is not described in the static geometry of an MCNPX model. The special case of non-static surfaces for rotation about a stationary point in space has been developed for MCNPX. In addition, velocity dependent kinematics due to the motion of the medium have been implemented. This implementation allows for the simulation of rotating objects at speeds comparable to the velocity of cold neutrons. Applications of the chopper extension will be discussed, including the direct simulation of a bandwidth chopper system, the thermalization of neutrons inside a spinning material, and the discussion of the implementation of a spinning single crystal.