| 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>5.3. Particles</title><link rel="stylesheet" href="../xml/XSLCustomizationLayer/G4HTMLStylesheet.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.71.1"><link rel="start" href="index.html" title="Geant4 User's Guide for Application Developers"><link rel="up" href="ch05.html" title="Chapter 5. Tracking and Physics"><link rel="prev" href="ch05s02.html" title="5.2. Physics Processes"><link rel="next" href="ch05s04.html" title="5.4. Production Threshold versus Tracking Cut"><script language="JavaScript">
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| 8 | </script></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5.3.
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| 9 | Particles
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| 10 | </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch05s02.html"><img src="AllResources/IconsGIF/prev.gif" alt="Prev"></a> </td><th width="60%" align="center">Chapter 5.
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| 11 | Tracking and Physics
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| 12 | </th><td width="20%" align="right"> <a accesskey="n" href="ch05s04.html"><img src="AllResources/IconsGIF/next.gif" alt="Next"></a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sect.Parti"></a>5.3.
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| 13 | Particles
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| 14 | </h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.Parti.Basic"></a>5.3.1.
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| 15 | Basic concepts
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| 16 | </h3></div></div></div><p>
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| 17 | There are three levels of classes to describe particles in Geant4.
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| 18 |
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| 19 | </p><div class="variablelist"><dl><dt><span class="term">
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| 20 | <span class="emphasis"><em>G4ParticleDefinition</em></span>
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| 21 | </span></dt><dd>
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| 22 | defines a particle
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| 23 | </dd><dt><span class="term">
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| 24 | <span class="emphasis"><em>G4DynamicParticle</em></span>
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| 25 | </span></dt><dd>
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| 26 | describes a particle interacting with materials
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| 27 | </dd><dt><span class="term">
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| 28 | <span class="emphasis"><em>G4Track</em></span>
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| 29 | </span></dt><dd>
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| 30 | describes a particle traveling in space and time
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| 31 | </dd></dl></div><p>
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| 32 | </p><p>
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| 33 | <span class="emphasis"><em>G4ParticleDefinition</em></span> aggregates information to
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| 34 | characterize a particle's properties, such as name, mass, spin,
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| 35 | life time, and decay modes. <span class="emphasis"><em>G4DynamicParticle</em></span> aggregates
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| 36 | information to describe the dynamics of particles, such as energy,
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| 37 | momentum, polarization, and proper time, as well as ``particle
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| 38 | definition'' information. <span class="emphasis"><em>G4Track</em></span> includes all information
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| 39 | necessary for tracking in a detector simulation, such as time,
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| 40 | position, and step, as well as ``dynamic particle''
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| 41 | information.
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| 42 | </p><p>
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| 43 | <span class="emphasis"><em>G4Track</em></span> has all the information necessary for tracking in
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| 44 | Geant4. It includes position, time, and step, as well as
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| 45 | kinematics. Details of <span class="emphasis"><em>G4Track</em></span> will be described in
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| 46 | <a href="ch05.html#sect.Track" title="5.1.
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| 47 | Tracking
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| 48 | ">Section 5.1</a>.
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| 49 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.Parti.Def"></a>5.3.2.
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| 50 | Definition of a particle
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| 51 | </h3></div></div></div><p>
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| 52 | There are a large number of elementary particles and nuclei. Geant4
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| 53 | provides the <span class="emphasis"><em>G4ParticleDefinition</em></span> class to represent
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| 54 | particles, and various particles, such as the electron, proton, and
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| 55 | gamma have their own classes derived from
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| 56 | <span class="emphasis"><em>G4ParticleDefinition</em></span>.
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| 57 | </p><p>
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| 58 | We do not need to make a class in Geant4 for every kind of
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| 59 | particle in the world. There are more than 100 types of particles
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| 60 | defined in Geant4 by default. Which particles should be included,
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| 61 | and how to implement them, is determined according to the following
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| 62 | criteria. (Of course, the user can define any particles he wants.
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| 63 | Please see the <span class="bold"><strong>User's Guide: For ToolKit
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| 64 | Developers</strong></span>).
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| 65 | </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sect.Parti.Def.PartiList"></a>5.3.2.1.
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| 66 | Particle List in Geant4
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| 67 | </h4></div></div></div><p>
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| 68 | This list includes all particles in Geant4 and you can see
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| 69 | properties of particles such as
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| 70 |
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| 71 | </p><div class="itemizedlist"><ul type="disc" compact><li><p>
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| 72 | PDG encoding
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| 73 | </p></li><li><p>
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| 74 | mass and width
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| 75 | </p></li><li><p>
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| 76 | electric charge
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| 77 | </p></li><li><p>
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| 78 | spin, isospin and parity
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| 79 | </p></li><li><p>
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| 80 | magnetic moment
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| 81 | </p></li><li><p>
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| 82 | quark contents
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| 83 | </p></li><li><p>
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| 84 | life time and decay modes
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| 85 | </p></li></ul></div><p>
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| 86 | </p><p>
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| 87 | Here is a list of particles in Geant4. This list is generated
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| 88 | automatically by using Geant4 functionality, so listed values are
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| 89 | same as those in your Geant4 application (as far as you do not
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| 90 | change source codes).
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| 91 | </p><h5><a name="id470604"></a>
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| 92 | Categories
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| 93 | </h5><p>
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| 94 | </p><div class="itemizedlist"><ul type="disc" compact><li><p>
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| 95 | <a href="./AllResources/TrackingAndPhysics/particleList.src/quarks/index.html" target="_top">
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| 96 | gluon / quarks / di-quarks
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| 97 | </a>
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| 98 | </p></li><li><p>
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| 99 | <a href="./AllResources/TrackingAndPhysics/particleList.src/leptons/index.html" target="_top">
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| 100 | leptons
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| 101 | </a>
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| 102 | </p></li><li><p>
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| 103 | <a href="./AllResources/TrackingAndPhysics/particleList.src/mesons/index.html" target="_top">
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| 104 | mesons
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| 105 | </a>
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| 106 | </p></li><li><p>
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| 107 | <a href="./AllResources/TrackingAndPhysics/particleList.src/baryons/index.html" target="_top">
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| 108 | baryons
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| 109 | </a>
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| 110 | </p></li><li><p>
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| 111 | <a href="./AllResources/TrackingAndPhysics/particleList.src/ions/index.html" target="_top">
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| 112 | ions
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| 113 | </a>
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| 114 | </p></li><li><p>
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| 115 | <a href="./AllResources/TrackingAndPhysics/particleList.src/others/index.html" target="_top">
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| 116 | others
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| 117 | </a>
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| 118 | </p></li></ul></div><p>
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| 119 | </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sect.Parti.Def.Classif"></a>5.3.2.2.
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| 120 | Classification of particles
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| 121 | </h4></div></div></div><p>
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| 122 | </p><div class="orderedlist"><ol type="1" compact><li><p>
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| 123 | </p><p>
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| 124 | elementary particles which should be tracked in Geant4 volumes
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| 125 | </p><p>
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| 126 | </p><p>
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| 127 | All particles that can fly a finite length and interact with
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| 128 | materials in detectors are included in this category. In addition,
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| 129 | some particles with a very short lifetime are included
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| 130 | for user's convenience.
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| 131 |
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| 132 | </p><div class="orderedlist"><ol type="a" compact><li><p>
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| 133 | stable particles
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| 134 | </p><p>
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| 135 | Stable means that the particle can not decay, or has a very small
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| 136 | possibility to decay in detectors, e.g., gamma, electron, proton,
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| 137 | and neutron.
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| 138 | </p><p>
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| 139 | </p></li><li><p>
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| 140 | long life (>10<sup>-14</sup>sec) particles
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| 141 | </p><p>
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| 142 | Particles which may travel a finite length, e.g., muon, charged
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| 143 | pions.
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| 144 | </p><p>
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| 145 | </p></li><li><p>
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| 146 | short life particles that decay immediately in Geant4
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| 147 | </p><p>
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| 148 | For example, pi<sup>0</sup>, eta
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| 149 | </p><p>
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| 150 | </p></li><li><p>
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| 151 | K<sup>0</sup> system
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| 152 | </p><p>
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| 153 | K<sup>0</sup> "decays" immediately into
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| 154 | K<sup>0</sup><sub>S</sub>
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| 155 | or K<sup>0</sup><sub>L</sub>, and then
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| 156 | K<sup>0</sup><sub>S</sub>/
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| 157 | K<sup>0</sup><sub>L</sub> decays
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| 158 | according to its life time and decay modes.
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| 159 | </p><p>
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| 160 | </p></li><li><p>
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| 161 | optical photon
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| 162 | </p><p>
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| 163 | Gamma and optical photon are distinguished in the simulation
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| 164 | view, though both are the same particle (photons with different
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| 165 | energies). For example, optical photon is used for Cerenkov light
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| 166 | and scintillation light.
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| 167 | </p><p>
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| 168 | </p></li><li><p>
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| 169 | geantino/charged geantino
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| 170 | </p><p>
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| 171 | Geantino and charged geantino are virtual particles for
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| 172 | simulation which do not interact with materials and undertake
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| 173 | transportation processes only.
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| 174 | </p><p>
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| 175 | </p></li></ol></div><p>
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| 176 | </p><p>
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| 177 | </p></li><li><p>
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| 178 | nuclei
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| 179 | </p><p>
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| 180 | Any kinds of nucleus can be used in Geant4, such as alpha(He-4),
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| 181 | uranium-238 and excited states of carbon-14. In addition,
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| 182 | Geant4 provides hyper-nuclei. Nuclei in Geant4 are
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| 183 | divided into two groups from the viewpoint of implementation.
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| 184 | </p><div class="orderedlist"><ol type="a" compact><li><p>
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| 185 | light nuclei
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| 186 | </p><p>
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| 187 | Light nuclei frequently used in simulation, e.g., alpha, deuteron,
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| 188 | He3, triton.
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| 189 | </p><p>
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| 190 | </p></li><li><p>
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| 191 | heavy nuclei (including hyper-nuclei)
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| 192 | </p><p>
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| 193 | Nuclei other than those defined in the previous category.
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| 194 | </p><p>
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| 195 | </p></li></ol></div><p>
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| 196 |
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| 197 | Note that G4ParticleDefinition represents nucleus state and
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| 198 | G4DynamicParticle represents atomic state with some nucleus. Both
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| 199 | alpha particle with charge of +2e and helium atom with no charge
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| 200 | aggregates the same "particle definition" of G4Alpha, but different
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| 201 | G4DynamicParticle objects should be assigned to them. (Details can
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| 202 | be found below)
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| 203 | </p><p>
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| 204 | </p></li><li><p>
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| 205 | short-lived particles
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| 206 | </p><p>
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| 207 | Particles with very short life time decay immediately and are never
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| 208 | tracked in the detector geometry. These particles are usually used
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| 209 | only inside physics processes to implement some models of
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| 210 | interactions. <span class="emphasis"><em>G4VShortLivedParticle</em></span> is provided as
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| 211 | the base class for these particles. All classes related to particles in
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| 212 | this category can be found in <code class="literal">shortlived</code> sub-directory
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| 213 | under the <code class="literal">particles</code> directory.
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| 214 |
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| 215 | </p><div class="orderedlist"><ol type="a" compact><li><p>
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| 216 | quarks/di-quarks
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| 217 | </p><p>
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| 218 | For example, all 6 quarks.
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| 219 | </p><p>
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| 220 | </p></li><li><p>
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| 221 | gluon
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| 222 | </p></li><li><p>
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| 223 | baryon excited states with very short life
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| 224 | </p><p>
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| 225 | For example, spin 3/2 baryons and anti-baryons
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| 226 | </p><p>
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| 227 | </p></li><li><p>
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| 228 | meson excited states with very short life
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| 229 | </p><p>
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| 230 | For example, spin 1 vector bosons
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| 231 | </p><p>
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| 232 | </p></li></ol></div><p>
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| 233 | </p><p>
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| 234 | </p></li></ol></div><p>
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| 235 | </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sect.Parti.Def.Imple"></a>5.3.2.3.
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| 236 | Implementation of particles
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| 237 | </h4></div></div></div><p>
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| 238 | <span class="emphasis"><em>Single object created in the initialization :</em></span>
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| 239 | Categories a, b-1
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| 240 | </p><p>
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| 241 | These particles are frequently used for tracking in
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| 242 | Geant4. An individual class is defined for each particle in these
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| 243 | categories. The object in each class is unique.
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| 244 | The user can get pointers to these objects by using static methods
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| 245 | in their own classes. The unique object for each class is created
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| 246 | when its static method is called in the ``initialization phase''.
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| 247 | </p><p>
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| 248 | <span class="emphasis"><em>On-the-fly creation:</em></span> Category b-2
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| 249 | </p><p>
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| 250 | Ions will travel in a detector geometry and should
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| 251 | be tracked, however, the number of ions which may be used for
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| 252 | hadronic processes is so huge that ions are dynamically
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| 253 | created by requests from processes (and users).
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| 254 | Each ion corresponds to one object of the <span class="emphasis"><em>G4Ions</em></span>
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| 255 | class.
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| 256 | <span class="emphasis"><em>G4IonTable</em></span> class is a dictionary for ions.
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| 257 | <code class="literal">G4ParticleTable::GetIon()</code> method invokes
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| 258 | <code class="literal">G4IonTable::GetIon()</code> method to create ions
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| 259 | on the fly.
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| 260 | </p><p>
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| 261 | Users can register a <span class="emphasis"><em>G4IsotopeTable</em></span> to the
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| 262 | <span class="emphasis"><em>G4IonTable</em></span>. <span class="emphasis"><em>G4IsotopeTable</em></span>
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| 263 | describes properties of ions (exited energy, decay modes, life time
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| 264 | and magnetic moments), which are used to create ions.
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| 265 | </p><p>
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| 266 | <span class="emphasis"><em>Dynamic creation by processes:</em></span> Category c
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| 267 | </p><p>
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| 268 | Particle types in this category are are not created
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| 269 | by default, but will only be created by request from processes or
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| 270 | directly by users. Each shortlived particle corresponds to one
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| 271 | object of a class derived from <span class="emphasis"><em>G4VshortLivedParticle</em></span>,
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| 272 | and it will be created dynamically during the ``initialization
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| 273 | phase''.
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| 274 | </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sect.Parti.Def.G4Parti"></a>5.3.2.4.
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| 275 | G4ParticleDefinition
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| 276 | </h4></div></div></div><p>
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| 277 | The <span class="emphasis"><em>G4ParticleDefinition</em></span> class has ``read-only'' properties
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| 278 | to characterize individual particles, such as name, mass, charge,
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| 279 | spin, and so on. These properties are set during initialization of
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| 280 | each particle. Methods to get these properties are listed in
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| 281 | <a href="ch05s03.html#table.Parti_1" title="Table 5.2.
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| 282 | Methods to get particle properties.
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| 283 | ">Table 5.2</a>.
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| 284 |
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| 285 | </p><div class="table"><a name="table.Parti_1"></a><div class="table-contents"><table summary="
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| 286 | Methods to get particle properties.
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| 287 | " border="1"><colgroup><col><col></colgroup><tbody><tr><td>
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| 288 | <code class="literal">G4String GetParticleName()</code>
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| 289 | </td><td>
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| 290 | particle name
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| 291 | </td></tr><tr><td>
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| 292 | <code class="literal">G4double GetPDGMass()</code>
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| 293 | </td><td>
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| 294 | mass
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| 295 | </td></tr><tr><td>
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| 296 | <code class="literal">G4double GetPDGWidth()</code>
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| 297 | </td><td>
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| 298 | decay width
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| 299 | </td></tr><tr><td>
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| 300 | <code class="literal">G4double GetPDGCharge()</code>
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| 301 | </td><td>
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| 302 | electric charge
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| 303 | </td></tr><tr><td>
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| 304 | <code class="literal">G4double GetPDGSpin()</code>
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| 305 | </td><td>
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| 306 | spin
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| 307 | </td></tr><tr><td>
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| 308 | <code class="literal">G4double GetPDGMagneticMoment()</code>
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| 309 | </td><td>
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| 310 | magnetic moment (0: not defined or no magnetic moment)
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| 311 | </td></tr><tr><td>
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| 312 | <code class="literal">G4int GetPDGiParity()</code>
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| 313 | </td><td>
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| 314 | parity (0:not defined)
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| 315 | </td></tr><tr><td>
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| 316 | <code class="literal">G4int GetPDGiConjugation()</code>
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| 317 | </td><td>
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| 318 | charge conjugation (0:not defined)
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| 319 | </td></tr><tr><td>
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| 320 | <code class="literal">G4double GetPDGIsospin()</code>
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| 321 | </td><td>
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| 322 | iso-spin
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| 323 | </td></tr><tr><td>
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| 324 | <code class="literal">G4double GetPDGIsospin3()</code>
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| 325 | </td><td>
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| 326 | 3<sup>rd</sup>-component of iso-spin
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| 327 | </td></tr><tr><td>
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| 328 | <code class="literal">G4int GetPDGiGParity()</code>
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| 329 | </td><td>
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| 330 | G-parity (0:not defined)
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| 331 | </td></tr><tr><td>
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| 332 | <code class="literal">G4String GetParticleType()</code>
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| 333 | </td><td>
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| 334 | particle type
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| 335 | </td></tr><tr><td>
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| 336 | <code class="literal">G4String GetParticleSubType()</code>
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| 337 | </td><td>
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| 338 | particle sub-type
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| 339 | </td></tr><tr><td>
|
|---|
| 340 | <code class="literal">G4int GetLeptonNumber()</code>
|
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| 341 | </td><td>
|
|---|
| 342 | lepton number
|
|---|
| 343 | </td></tr><tr><td>
|
|---|
| 344 | <code class="literal">G4int GetBaryonNumber()</code>
|
|---|
| 345 | </td><td>
|
|---|
| 346 | baryon number
|
|---|
| 347 | </td></tr><tr><td>
|
|---|
| 348 | <code class="literal">G4int GetPDGEncoding()</code>
|
|---|
| 349 | </td><td>
|
|---|
| 350 | particle encoding number by PDG
|
|---|
| 351 | </td></tr><tr><td>
|
|---|
| 352 | <code class="literal">G4int GetAntiPDGEncoding()</code>
|
|---|
| 353 | </td><td>
|
|---|
| 354 | encoding for anti-particle of this particle
|
|---|
| 355 | </td></tr></tbody></table></div><p class="title"><b>Table 5.2.
|
|---|
| 356 | Methods to get particle properties.
|
|---|
| 357 | </b></p></div><p><br class="table-break">
|
|---|
| 358 | </p><p>
|
|---|
| 359 | <a href="ch05s03.html#table.Parti_2" title="Table 5.3.
|
|---|
| 360 | Methods to get particle decay modes and life time.
|
|---|
| 361 | ">Table 5.3</a> shows the methods of
|
|---|
| 362 | <span class="emphasis"><em>G4ParticleDefinition</em></span> for
|
|---|
| 363 | getting information about decay modes and the life time of the
|
|---|
| 364 | particle.
|
|---|
| 365 |
|
|---|
| 366 | </p><div class="table"><a name="table.Parti_2"></a><div class="table-contents"><table summary="
|
|---|
| 367 | Methods to get particle decay modes and life time.
|
|---|
| 368 | " border="1"><colgroup><col><col></colgroup><tbody><tr><td>
|
|---|
| 369 | <code class="literal">G4bool GetPDGStable()</code>
|
|---|
| 370 | </td><td>
|
|---|
| 371 | stable flag
|
|---|
| 372 | </td></tr><tr><td>
|
|---|
| 373 | <code class="literal">G4double GetPDGLifeTime()</code>
|
|---|
| 374 | </td><td>
|
|---|
| 375 | life time
|
|---|
| 376 | </td></tr><tr><td>
|
|---|
| 377 | <code class="literal">G4DecayTable* GetDecayTable()</code>
|
|---|
| 378 | </td><td>
|
|---|
| 379 | decay table
|
|---|
| 380 | </td></tr></tbody></table></div><p class="title"><b>Table 5.3.
|
|---|
| 381 | Methods to get particle decay modes and life time.
|
|---|
| 382 | </b></p></div><p><br class="table-break">
|
|---|
| 383 | </p><p>
|
|---|
| 384 | Users can modify these properties, though the other properties
|
|---|
| 385 | listed above can not be change without rebuilding the
|
|---|
| 386 | libraries.
|
|---|
| 387 | </p><p>
|
|---|
| 388 | Each particle has its own <span class="emphasis"><em>G4ProcessManger</em></span>
|
|---|
| 389 | object that manages a list of processes applicable to the
|
|---|
| 390 | particle.(see <a href="ch02s05.html#sect.HowToSpecPhysProc.ManagingProc" title="2.5.2.
|
|---|
| 391 | Managing Processes
|
|---|
| 392 | ">Section 2.5.2</a> )
|
|---|
| 393 | </p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.Parti.Dynam"></a>5.3.3.
|
|---|
| 394 | Dynamic particle
|
|---|
| 395 | </h3></div></div></div><p>
|
|---|
| 396 | The <span class="emphasis"><em>G4DynamicParticle</em></span> class has kinematics information for
|
|---|
| 397 | the particle and is used for describing the dynamics of physics
|
|---|
| 398 | processes. The properties in <span class="emphasis"><em>G4DynamicParticle</em></span> are listed in
|
|---|
| 399 | <a href="ch05s03.html#table.Parti_4" title="Table 5.4.
|
|---|
| 400 | Methods to set/get cut off values.
|
|---|
| 401 | ">Table 5.4</a>.
|
|---|
| 402 |
|
|---|
| 403 | </p><div class="table"><a name="table.Parti_4"></a><div class="table-contents"><table summary="
|
|---|
| 404 | Methods to set/get cut off values.
|
|---|
| 405 | " border="1"><colgroup><col><col></colgroup><tbody><tr><td>
|
|---|
| 406 | <code class="literal">G4double theDynamicalMass</code>
|
|---|
| 407 | </td><td>
|
|---|
| 408 | dynamical mass
|
|---|
| 409 | </td></tr><tr><td>
|
|---|
| 410 | <code class="literal">G4ThreeVector theMomentumDirection</code>
|
|---|
| 411 | </td><td>
|
|---|
| 412 | normalized momentum vector
|
|---|
| 413 | </td></tr><tr><td>
|
|---|
| 414 | <code class="literal">G4ParticleDefinition* theParticleDefinition</code>
|
|---|
| 415 | </td><td>
|
|---|
| 416 | definition of particle
|
|---|
| 417 | </td></tr><tr><td>
|
|---|
| 418 | <code class="literal">G4double theDynamicalSpin</code>
|
|---|
| 419 | </td><td>
|
|---|
| 420 | dynamical spin
|
|---|
| 421 | (i.e. total angular momentum as a ion/atom )
|
|---|
| 422 | </td></tr><tr><td>
|
|---|
| 423 | <code class="literal">G4ThreeVector thePolarization</code>
|
|---|
| 424 | </td><td>
|
|---|
| 425 | polarization vector
|
|---|
| 426 | </td></tr><tr><td>
|
|---|
| 427 | <code class="literal">G4double theMagneticMoment</code>
|
|---|
| 428 | </td><td>
|
|---|
| 429 | dynamical magnetic moment
|
|---|
| 430 | (i.e. total magnetic moment as a ion/atom )
|
|---|
| 431 | </td></tr><tr><td>
|
|---|
| 432 | <code class="literal">G4double theKineticEnergy</code>
|
|---|
| 433 | </td><td>
|
|---|
| 434 | kinetic energy
|
|---|
| 435 | </td></tr><tr><td>
|
|---|
| 436 | <code class="literal">G4double theProperTime</code>
|
|---|
| 437 | </td><td>
|
|---|
| 438 | proper time
|
|---|
| 439 | </td></tr><tr><td>
|
|---|
| 440 | <code class="literal">G4double theDynamicalCharge</code>
|
|---|
| 441 | </td><td>
|
|---|
| 442 | dynamical electric charge
|
|---|
| 443 | (i.e. total electric charge as a ion/atom )
|
|---|
| 444 | </td></tr><tr><td>
|
|---|
| 445 | <code class="literal">G4ElectronOccupancy* theElectronOccupancy</code>
|
|---|
| 446 | </td><td>
|
|---|
| 447 | electron orbits for ions
|
|---|
| 448 | </td></tr></tbody></table></div><p class="title"><b>Table 5.4.
|
|---|
| 449 | Methods to set/get cut off values.
|
|---|
| 450 | </b></p></div><p><br class="table-break">
|
|---|
| 451 | </p><p>
|
|---|
| 452 | Here, the dynamical mass is defined as the mass for the dynamic
|
|---|
| 453 | particle. For most cases, it is same as the mass defined in
|
|---|
| 454 | <span class="emphasis"><em>G4ParticleDefinition</em></span> class ( i.e. mass value given by
|
|---|
| 455 | <code class="literal">GetPDGMass()</code> method). However, there are two
|
|---|
| 456 | exceptions.
|
|---|
| 457 |
|
|---|
| 458 | </p><div class="itemizedlist"><ul type="disc" compact><li><p>
|
|---|
| 459 | resonance particle
|
|---|
| 460 | </p></li><li><p>
|
|---|
| 461 | ions
|
|---|
| 462 | </p></li></ul></div><p>
|
|---|
| 463 | </p><p>
|
|---|
| 464 | Resonance particles have large mass width and the total energy of
|
|---|
| 465 | decay products at the center of mass system can be different event
|
|---|
| 466 | by event.
|
|---|
| 467 | </p><p>
|
|---|
| 468 | As for ions, <span class="emphasis"><em>G4ParticleDefintion</em></span> defines a nucleus and
|
|---|
| 469 | <span class="emphasis"><em>G4DynamicParticle</em></span> defines an atom.
|
|---|
| 470 | <span class="emphasis"><em>G4ElectronOccupancy</em></span> describes state of orbital electrons.
|
|---|
| 471 | So, the dynamic mass can be different from the PDG mass by the mass
|
|---|
| 472 | of electrons (and their binding energy). In addition, the dynamical
|
|---|
| 473 | charge, spin and magnetic moment are those of the atom/ion
|
|---|
| 474 | (i.e. including nucleus and orbit electrons).
|
|---|
| 475 | </p><p>
|
|---|
| 476 | Decay products of heavy flavor particles are given in many event
|
|---|
| 477 | generators. In such cases, <span class="emphasis"><em>G4VPrimaryGenerator</em></span> sets this
|
|---|
| 478 | information in <code class="literal">*thePreAssignedDecayProducts</code>. In addition,
|
|---|
| 479 | decay time of the particle can be set arbitrarily time by using
|
|---|
| 480 | <code class="literal">PreAssignedDecayProperTime</code>.
|
|---|
| 481 | </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch05s02.html"><img src="AllResources/IconsGIF/prev.gif" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="ch05.html"><img src="AllResources/IconsGIF/up.gif" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="ch05s04.html"><img src="AllResources/IconsGIF/next.gif" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">5.2.
|
|---|
| 482 | Physics Processes
|
|---|
| 483 | </td><td width="20%" align="center"><a accesskey="h" href="index.html"><img src="AllResources/IconsGIF/home.gif" alt="Home"></a></td><td width="40%" align="right" valign="top"> 5.4.
|
|---|
| 484 | Production Threshold versus Tracking Cut
|
|---|
| 485 | </td></tr></table></div></body></html>
|
|---|
