MCNP geometry transformation and plotter equations

The MCNP Monte Carlo radiation-transport code contains versatile capabilities to develop and plot geometries used in simulations. Although these capabilities have been available in MCNP since the late 1970s, many of the derivational details underpinning these capabilities are not contained in the MCNP manual and do not appear to have been documented in Los Alamos reports or the published literature. Derivations of many of the equations underlying the MCNP geometry transformation and geometry plot utility are presented here. Although this document does not include derivations of all of the expressions contained in MCNP, its contents should nevertheless provide the reader with a deeper understanding of the geometry transformation and plotting features than can be obtained using only the MCNP theory manual.

► Detailed derivations of geometry transformation and graphics equations are given. ► The derivations illuminate how visually appealing plots are created. ► The graphics equations are associated with specific lines of code. ► A coding curiosity is identified.