| 1 | \chapter[Introduction] |
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| 2 | {Introduction} |
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| 3 | |
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| 4 | \section{Scope of This Manual} |
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| 5 | |
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| 6 | The Physics Reference Manual provides detailed explanations of the physics |
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| 7 | implemented in the Geant4 toolkit. The manual's purpose is threefold: |
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| 8 | |
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| 9 | \begin{itemize} |
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| 10 | |
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| 11 | \item to present the theoretical formulation, model, or parameterization of |
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| 12 | the physics interactions included in Geant4, |
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| 13 | |
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| 14 | \item to describe the probability of the occurrence of an interaction and the |
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| 15 | sampling mechanisms required to simulate it, and |
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| 16 | |
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| 17 | \item to serve as a reference for toolkit users and developers who wish to |
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| 18 | consult the underlying physics of an interaction. |
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| 19 | |
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| 20 | \end{itemize} |
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| 21 | |
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| 22 | This manual does not discuss code implementation or how to use the |
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| 23 | implemented physics interactions in a simulation. These topics are |
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| 24 | discussed in the User's Guide for Application Developers. Details |
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| 25 | of the object-oriented design and functionality of the Geant4 toolkit |
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| 26 | are given in the User's Guide for Toolkit Developers. The |
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| 27 | Installation Guide for Setting up Geant4 in Your Computing Environment |
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| 28 | describes how to get the Geant4 code, install it, and run it. |
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| 29 | |
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| 30 | \section{Definition of Terms} |
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| 31 | |
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| 32 | Several terms used throughout the Physics Reference Manual have specific |
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| 33 | meaning within Geant4, but are not well-defined in general usage. The |
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| 34 | definitions of these terms are given here. |
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| 35 | |
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| 36 | \begin{itemize} |
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| 37 | |
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| 38 | \item {\bf process} - a C++ class which describes how and when a specific |
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| 39 | kind of physical interaction takes place along a |
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| 40 | particle track. A given particle type typically |
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| 41 | has several processes assigned to it. |
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| 42 | Occaisionally ``process'' refers to the interaction |
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| 43 | which the process class describes. |
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| 44 | |
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| 45 | \item {\bf model} - a C++ class whose methods implement the details of an |
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| 46 | interaction, such as its kinematics. One or more |
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| 47 | models may be assigned to each process. In sections |
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| 48 | discussing the theory of an interaction, ``model'' may |
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| 49 | refer to the formulae or parameterization on which |
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| 50 | the model class is based. |
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| 51 | |
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| 52 | \item {\bf Geant3} - a physics simulation tool written in Fortran, |
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| 53 | and the predecessor of Geant4. Although many |
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| 54 | references are made to Geant3, no knowledge |
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| 55 | of it is required to understand this manual. |
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| 56 | |
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| 57 | \end{itemize} |
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| 58 | |
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| 59 | \section{Status of this document} |
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| 60 | 4.12.01 created by D.H. Wright |
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| 61 | |
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| 62 | |
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