Monte Carlo N-Particle Simulations for Nuclear Detection and Safeguards

Table of contents: Contents .......................................................................................................................................... 4 Introduction ..................................................................................................................................... 8 Section 1: Basic Concepts ............................................................................................................... 8 1.1 Geometry ............................................................................................................................... 8 1.1.1 Simplest possible input file............................................................................................. 8 1.1.2 Running MCNP - Simplest Case ................................................................................... 9 1.1.3 Simple Input File .......................................................................................................... 12 1.1.4 Running and plotting MCNP geometries ..................................................................... 14 1.1.5 Surfaces and Complicated Cells: Intersections and Unions ......................................... 17 1.1.6 Duplicate Cells, Compliments and Translations: LIKE BUT and TRCL .................... 22 1.1.7 Filled Cells: Universes.................................................................................................. 26 1.1.8 Lattice Geometries ........................................................................................................ 32 1.1.9 Fully Specified Lattice Geometries .............................................................................. 40 1.2 Materials and Cross Sections .............................................................................................. 45 1.2.1 Specifying Materials ..................................................................................................... 45 1.2.2 Neutron cross sections .................................................................................................. 46 1.2.3 Low-energy neutron problems - thermal free gas treatment ........................................ 49 1.2.4 Low-energy neutron problem data - S(α,β) thermal treatment .................................... 50 1.2.5 Photon cross sections .................................................................................................... 53 1.2.6 Electron stopping powers for coupled photon and electron problems ......................... 57 1.2.7 Data and models for Ions and Charged Particles .......................................................... 61 1.2.8 Additional data diagnostics and recommendations ...................................................... 62 1.3 Sources ................................................................................................................................ 63 1.3.1 SDEF Fixed Sources ..................................................................................................... 63 1.3.2 SDEF Source Distributions .......................................................................................... 66 1.3.3 SDEF Dependent Distributions: DS ............................................................................. 69 1.3.4 Criticality Sources ........................................................................................................ 71 1.3.5 Surface Source Read and Write (SSR, SSW) ......................................................... 77 1.3.6 Checking sources .................................................................................................... 87 1.4 Output and Tallies ................................................