| 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>4.7. Parallel Geometries</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="ch04.html" title="Chapter 4. Detector Definition and Response"><link rel="prev" href="ch04s06.html" title="4.6. Object Persistency"><link rel="next" href="ch04s08.html" title="4.8. Command-based scoring"><script language="JavaScript">
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| 4 | var url = "AllResources/Detector/geometry.src/" + fName;
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| 5 | RemoteWin=window.open(url,"","resizable=no,toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,copyhistory=0,width=520,height=520")
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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">4.7.
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| 9 | Parallel Geometries
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| 10 | </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch04s06.html"><img src="AllResources/IconsGIF/prev.gif" alt="Prev"></a> </td><th width="60%" align="center">Chapter 4.
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| 11 | Detector Definition and Response
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| 12 | </th><td width="20%" align="right"> <a accesskey="n" href="ch04s08.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.ParaGeom"></a>4.7.
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| 13 | Parallel Geometries
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| 14 | </h2></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">
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| 15 | Notice
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| 16 | </h3><p>
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| 17 | As of Geant4 release 8.2, this functionality for defining parallel
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| 18 | geometries is still in <span class="emphasis"><em>beta</em></span> release. We appreciate your
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| 19 | feedback.
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| 20 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.ParaGeom.ParaWrld"></a>4.7.1.
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| 21 | A parallel world
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| 22 | </h3></div></div></div><p>
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| 23 | Occasionally, it is not straightforward to define geometries for
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| 24 | sensitive detectors, importance geometries or envelopes for shower
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| 25 | parameterization to be coherently assigned to volumes in the
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| 26 | tracking (mass) geometry. The new parallel navigation functionality
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| 27 | allows the user to define more than one worlds simultaneously. The
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| 28 | new <code class="literal">G4Transportation</code> process will see all worlds
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| 29 | simultaneously; steps will be limited by both boundaries of the
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| 30 | mass geometry and parallel geometries.
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| 31 | </p><p>
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| 32 | In a parallel world, the user can define volumes in arbitrary
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| 33 | manner with sensitivity, regions, shower parameterization setups,
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| 34 | and/or importance weight for biasing. Volumes in different worlds
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| 35 | can overlap.
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| 36 | </p><p>
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| 37 | Here are restrictions to be considered for the parallel
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| 38 | geometry:
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| 39 |
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| 40 | </p><div class="itemizedlist"><ul type="disc" compact><li><p>
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| 41 | Materials, production thresholds and EM field are used only
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| 42 | from the mass geometry. Even if such <span class="emphasis"><em>physical</em></span>
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| 43 | quantities are defined in a parallel world, they do not affect to the
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| 44 | simulation.
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| 45 | </p></li><li><p>
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| 46 | Although all worlds will be comprehensively taken care by the
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| 47 | <code class="literal">G4Transportation</code> process for the navigation,
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| 48 | each parallel world must have its own process assigned to achieve
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| 49 | its purpose.
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| 50 | For example: in case the user defines a sensitive detector to a
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| 51 | parallel world, a process dedicated to the parallel world is
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| 52 | responsible to invoke this detector.
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| 53 | The <code class="literal">G4SteppingManager</code>
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| 54 | treats only the detectors in the mass geometry. For this case of
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| 55 | detector sensitivity defined in a parallel world, a
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| 56 | <code class="literal">G4ParallelWorldScoringProcess</code> process must be defined
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| 57 | in the physics list (see
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| 58 | <a href="ch04s07.html#sect.ParaGeom.SenstivParaWrld" title="4.7.3.
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| 59 | Detector sensitivity in a parallel world
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| 60 | ">Section 4.7.3</a>).
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| 61 | </p></li></ul></div><p>
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| 62 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.ParaGeom.DefParaWrld"></a>4.7.2.
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| 63 | Defining a parallel world
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| 64 | </h3></div></div></div><p>
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| 65 | A parallel world should be defined in the <code class="literal">Construct()</code>
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| 66 | virtual method of the user's class derived from the abstract base
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| 67 | class <span class="emphasis"><em>G4VUserParallelWorld</em></span>.
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| 68 |
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| 69 | </p><div class="example"><a name="id433212"></a><p class="title"><b>Example 4.17.
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| 70 | An example header file of a concrete user parallel world class.
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| 71 | </b></p><div class="example-contents"><pre class="programlisting">
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| 72 | #ifndef MyParallelWorld_h
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| 73 | #define MyParallelWorld_h 1
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| 74 |
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| 75 | #include "globals.hh"
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| 76 | #include "G4VUserParallelWorld.hh"
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| 77 |
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| 78 | class MyParallelWorld : <span class="color_red">public G4VUserParallelWorld</span>
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| 79 | {
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| 80 | public:
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| 81 | MyParallelWorld(G4String worldName);
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| 82 | virtual ~MyParallelWorld();
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| 83 |
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| 84 | public:
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| 85 | <span class="color_red">virtual void Construct();</span>
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| 86 | };
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| 87 |
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| 88 | #endif
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| 89 | </pre></div></div><p><br class="example-break">
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| 90 | </p><p>
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| 91 | A parallel world must have its unique name, which should be set
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| 92 | to the <code class="literal">G4VUserParallelWorld</code> base class as an argument of
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| 93 | the base class constructor.
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| 94 | </p><p>
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| 95 | The world physical volume of the parallel world is provided by
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| 96 | the <code class="literal">G4RunManager</code> as a clone of the mass geometry. In the
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| 97 | <code class="literal">Construct()</code> virtual method of the user's class, the
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| 98 | pointer to this cloned world physical volume is available through
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| 99 | the <code class="literal">GetWorld()</code> method defined in the base class. The user
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| 100 | should fill the volumes in the parallel world by using this
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| 101 | provided world volume. For a logical volume in a parallel world,
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| 102 | the material pointer can be <code class="literal">NULL</code>. Even if specified a
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| 103 | valid material pointer, it will not be taken into account by any
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| 104 | physics process.
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| 105 |
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| 106 |
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| 107 | </p><div class="example"><a name="id433280"></a><p class="title"><b>Example 4.18.
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| 108 | An example source code of a concrete user parallel world class.
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| 109 | </b></p><div class="example-contents"><pre class="programlisting">
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| 110 | #include "MyParallelWorld.hh"
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| 111 | #include "G4LogicalVolume.hh"
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| 112 | #include "G4VPhysicalVolume.hh"
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| 113 | #include "G4Box.hh"
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| 114 | #include "G4PVPlacement.hh"
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| 115 |
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| 116 | MyParallelWorld::MyParallelWorld(G4String worldName)
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| 117 | <span class="color_red">:G4VUserParallelWorld(worldName)</span>
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| 118 | {;}
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| 119 |
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| 120 | MyParallelWorld::~MyParallelWorld()
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| 121 | {;}
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| 122 |
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| 123 | void MyParallelWorld::Construct()
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| 124 | {
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| 125 | G4VPhysicalVolume* ghostWorld = <span class="color_red">GetWorld();</span>
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| 126 | G4LogicalVolume* worldLogical = ghostWorld->GetLogicalVolume();
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| 127 |
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| 128 | // place volumes in the parallel world here. For example ...
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| 129 | //
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| 130 | G4Box * ghostSolid = new G4Box("GhostdBox", 60.*cm, 60.*cm, 60.*cm);
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| 131 | G4LogicalVolume * ghostLogical
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| 132 | = new G4LogicalVolume(ghostSolid, 0, "GhostLogical", 0, 0, 0);
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| 133 | new G4PVPlacement(0, G4ThreeVector(), ghostLogical,
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| 134 | "GhostPhysical", worldLogical, 0, 0);
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| 135 | }
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| 136 | </pre></div></div><p><br class="example-break">
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| 137 | </p><p>
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| 138 | In case the user needs to define more than one parallel worlds,
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| 139 | each of them must be implemented through its dedicated class. Each
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| 140 | parallel world should be registered to the mass geometry class
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| 141 | using the method <code class="literal">RegisterParallelWorld()</code> available through
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| 142 | the class <code class="literal">G4VUserDetectorConstruction</code>. The registration
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| 143 | must be done -before- the mass world is registed to the
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| 144 | <code class="literal">G4RunManager</code>.
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| 145 |
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| 146 | </p><div class="example"><a name="id433338"></a><p class="title"><b>Example 4.19.
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| 147 | Typical implementation in the <code class="literal">main()</code> to define a parallel
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| 148 | world.
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| 149 | </b></p><div class="example-contents"><pre class="programlisting">
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| 150 | // RunManager construction
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| 151 | //
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| 152 | G4RunManager* runManager = new G4RunManager;
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| 153 |
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| 154 | // mass world
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| 155 | //
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| 156 | MyDetectorConstruction* massWorld = new MyDetectorConstruction;
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| 157 |
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| 158 | // parallel world
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| 159 | //
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| 160 | massWorld-><span class="color_red">RegisterParallelWorld</span>(new MyParallelWorld("ParallelScoringWorld"));
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| 161 |
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| 162 | // set mass world to run manager
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| 163 | //
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| 164 | runManager->SetUserInitialization(massWorld);
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| 165 | </pre></div></div><p><br class="example-break">
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| 166 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.ParaGeom.SenstivParaWrld"></a>4.7.3.
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| 167 | Detector sensitivity in a parallel world
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| 168 | </h3></div></div></div><p>
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| 169 | Any kind of <code class="literal">G4VSensitiveDetector</code> object can be defined
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| 170 | in volumes in a parallel world, exactly at the same manner for the
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| 171 | mass geometry. Once the user defines the sensitive detector in a
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| 172 | parallel world, he/she must define a process which takes care of
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| 173 | these detectors.
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| 174 | </p><p>
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| 175 | The <code class="literal">G4ParallelWorldScoringProcess</code> is the class provided
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| 176 | for this purpose. This process must be defined to all kinds of
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| 177 | particles which need to be "detected". This process must be ordered
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| 178 | <span class="color_red">
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| 179 | just after <code class="literal">G4Transporation</code> and prior
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| 180 | to any other physics processes</span>. The name of the parallel
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| 181 | world where the <code class="literal">G4ParallelWorldScoringProcess</code> is
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| 182 | responsible for, must be defined through the method
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| 183 | <code class="literal">SetParallelWorld()</code> available from the class
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| 184 | <code class="literal">G4ParallelWorldScoringProcess</code>. If the user has more than
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| 185 | one parallel worlds with detectors, for each of the parallel
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| 186 | worlds, dedicated <code class="literal">G4ParallelWorldScoringProcess</code> objects
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| 187 | must be instantiated with the name of each parallel world
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| 188 | respectively and registered to the particles.
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| 189 |
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| 190 | </p><div class="example"><a name="id433442"></a><p class="title"><b>Example 4.20.
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| 191 | Define <code class="literal">G4ParallelWorldScoringProcess</code>.
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| 192 | </b></p><div class="example-contents"><pre class="programlisting">
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| 193 | // Add parallel world scoring process
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| 194 | //
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| 195 | G4ParallelWorldScoringProcess* theParallelWorldScoringProcess
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| 196 | = new <span class="color_red">G4ParallelWorldScoringProcess</span>("ParaWorldScoringProc");
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| 197 | theParallelWorldScoringProcess-><span class="color_red">SetParallelWorld</span>("ParallelScoringWorld");
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| 198 |
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| 199 | theParticleIterator->reset();
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| 200 | while( (*theParticleIterator)() )
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| 201 | {
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| 202 | G4ParticleDefinition* particle = theParticleIterator->value();
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| 203 | if (!particle->IsShortLived())
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| 204 | {
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| 205 | G4ProcessManager* pmanager = particle->GetProcessManager();
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| 206 | pmanager->AddProcess(theParallelWorldScoringProcess);
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| 207 | pmanager->SetProcessOrderingToLast(theParallelWorldScoringProcess, idxAtRest);
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| 208 | pmanager->SetProcessOrdering(theParallelWorldScoringProcess, idxAlongStep, 1);
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| 209 | pmanager->SetProcessOrderingToLast(theParallelWorldScoringProcess, idxPostStep);
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| 210 | }
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| 211 | }
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| 212 | </pre></div></div><p><br class="example-break">
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| 213 | </p><p>
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| 214 | At the end of processing an event, all hits collections made for
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| 215 | the parallel world are stored in <code class="literal">G4HCofThisEvent</code> as well
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| 216 | as those for the mass geometry.
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| 217 | </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch04s06.html"><img src="AllResources/IconsGIF/prev.gif" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="ch04.html"><img src="AllResources/IconsGIF/up.gif" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="ch04s08.html"><img src="AllResources/IconsGIF/next.gif" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">4.6.
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| 218 | Object Persistency
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| 219 | </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"> 4.8.
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| 220 | Command-based scoring
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| 221 | </td></tr></table></div></body></html>
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