1 | <!-- ******************************************************** --> |
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2 | <!-- --> |
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3 | <!-- [History] --> |
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4 | <!-- Converted to DocBook: Katsuya Amako, Aug-2006 --> |
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5 | <!-- Changed by: Katsuya Amako, 21-Sep-1998 --> |
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6 | <!-- Changed by: Dennis Wright, 27-Nov-2001 --> |
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7 | <!-- Proof read by: Joe Chuma, 30-Jun-1999 --> |
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8 | <!-- --> |
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9 | <!-- ******************************************************** --> |
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10 | |
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11 | |
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12 | <!-- ******************* Section (Level#1) ****************** --> |
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13 | <sect1 id="sect.Digi"> |
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14 | <title> |
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15 | Digitization |
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16 | </title> |
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17 | |
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18 | |
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19 | <!-- ******************* Section (Level#2) ****************** --> |
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20 | <sect2 id="sect.Digi.Digi"> |
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21 | <title> |
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22 | Digi |
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23 | </title> |
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24 | |
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25 | <para> |
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26 | A hit is created by a sensitive detector when a step goes through |
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27 | it. Thus, the sensitive detector is associated to the corresponding |
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28 | <emphasis>G4LogicalVolume</emphasis> object(s). On the other hand, a digit is |
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29 | created using information of hits and/or other digits by a |
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30 | digitizer module. The digitizer module is not associated with any |
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31 | volume, and you have to implicitly invoke the <literal>Digitize()</literal> |
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32 | method of your concrete <emphasis>G4VDigitizerModule</emphasis> class. |
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33 | </para> |
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34 | |
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35 | <para> |
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36 | Typical usages of digitizer module include: |
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37 | |
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38 | <itemizedlist spacing="compact"> |
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39 | <listitem><para> |
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40 | simulate ADC and/or TDC |
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41 | </para></listitem> |
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42 | <listitem><para> |
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43 | simulate readout scheme |
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44 | </para></listitem> |
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45 | <listitem><para> |
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46 | generate raw data |
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47 | </para></listitem> |
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48 | <listitem><para> |
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49 | simulate trigger logics |
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50 | </para></listitem> |
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51 | <listitem><para> |
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52 | simulate pile up |
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53 | </para></listitem> |
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54 | </itemizedlist> |
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55 | </para> |
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56 | |
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57 | |
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58 | <!-- ******* Bridgehead ******* --> |
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59 | <bridgehead renderas='sect4'> |
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60 | G4VDigi |
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61 | </bridgehead> |
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62 | |
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63 | <para> |
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64 | <emphasis>G4VDigi</emphasis> is an abstract base class which represents a |
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65 | digit. You have to inherit this base class and derive your own |
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66 | concrete digit class(es). The member data of your concrete digit |
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67 | class should be defined by yourself. <emphasis>G4VDigi</emphasis> has two virtual |
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68 | methods, <literal>Draw()</literal> and <literal>Print()</literal>. |
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69 | </para> |
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70 | |
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71 | <!-- ******* Bridgehead ******* --> |
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72 | <bridgehead renderas='sect4'> |
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73 | G4TDigiCollection |
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74 | </bridgehead> |
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75 | |
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76 | <para> |
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77 | <emphasis>G4TDigiCollection</emphasis> is a template class for digits |
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78 | collections, which is derived from the abstract base class |
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79 | <emphasis>G4VDigiCollection</emphasis>. <emphasis>G4Event</emphasis> has a |
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80 | <emphasis>G4DCofThisEvent</emphasis> object, which is a container class of |
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81 | collections of digits. The usages of <emphasis>G4VDigi</emphasis> and |
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82 | <emphasis>G4TDigiCollection</emphasis> are almost the same as <emphasis>G4VHit</emphasis> and |
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83 | <emphasis>G4THitsCollection</emphasis>, respectively, explained in the previous |
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84 | section. |
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85 | </para> |
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86 | |
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87 | </sect2> |
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88 | |
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89 | |
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90 | <!-- ******************* Section (Level#2) ****************** --> |
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91 | <sect2 id="sect.Digi.DigMod"> |
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92 | <title> |
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93 | Digitizer module |
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94 | </title> |
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95 | |
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96 | <!-- ******* Bridgehead ******* --> |
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97 | <bridgehead renderas='sect4'> |
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98 | G4VDigitizerModule |
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99 | </bridgehead> |
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100 | |
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101 | <para> |
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102 | <emphasis>G4VDigitizerModule</emphasis> is an abstract base class which |
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103 | represents a digitizer module. It has a pure virtual method, |
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104 | <literal>Digitize()</literal>. A concrete digitizer module must have an |
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105 | implementation of this virtual method. The Geant4 kernel classes do |
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106 | not have a ``built-in'' invocation to the <literal>Digitize()</literal> |
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107 | method. You have to implement your code to invoke this method of |
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108 | your digitizer module. |
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109 | </para> |
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110 | |
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111 | <para> |
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112 | In the <literal>Digitize()</literal> method, you construct your |
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113 | <emphasis>G4VDigi</emphasis> concrete class objects and store them to your |
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114 | <emphasis>G4TDigiCollection</emphasis> concrete class object(s). Your |
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115 | collection(s) should be associated with the <emphasis>G4DCofThisEvent</emphasis> |
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116 | object. |
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117 | </para> |
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118 | |
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119 | <!-- ******* Bridgehead ******* --> |
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120 | <bridgehead renderas='sect4'> |
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121 | G4DigiManager |
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122 | </bridgehead> |
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123 | |
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124 | <para> |
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125 | <emphasis>G4DigiManager</emphasis> is the singleton manager class of the |
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126 | digitizer modules. All of your concrete digitizer modules should be |
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127 | registered to <emphasis>G4DigiManager</emphasis> with their unique names. |
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128 | |
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129 | <informalexample> |
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130 | <programlisting> |
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131 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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132 | MyDigitizer * myDM = new MyDigitizer( "/myDet/myCal/myEMdigiMod" ); |
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133 | fDM->AddNewModule(myDM); |
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134 | </programlisting> |
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135 | </informalexample> |
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136 | </para> |
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137 | |
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138 | <para> |
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139 | Your concrete digitizer module can be accessed from your code using |
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140 | the unique module name. |
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141 | |
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142 | <informalexample> |
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143 | <programlisting> |
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144 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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145 | MyDigitizer * myDM = fDM->FindDigitizerModule( "/myDet/myCal/myEMdigiMod" ); |
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146 | myDM->Digitize(); |
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147 | </programlisting> |
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148 | </informalexample> |
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149 | </para> |
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150 | |
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151 | <para> |
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152 | Also, <emphasis>G4DigiManager</emphasis> has a <emphasis>Digitize()</emphasis> |
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153 | method which takes the unique module name. |
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154 | |
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155 | <informalexample> |
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156 | <programlisting> |
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157 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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158 | MyDigitizer * myDM = fDM->Digitize( "/myDet/myCal/myEMdigiMod" ); |
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159 | </programlisting> |
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160 | </informalexample> |
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161 | </para> |
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162 | |
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163 | <!-- ******* Bridgehead ******* --> |
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164 | <bridgehead renderas='sect4'> |
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165 | How to get hitsCollection and/or digiCollection |
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166 | </bridgehead> |
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167 | |
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168 | <para> |
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169 | <emphasis>G4DigiManager</emphasis> has the following methods to access to the |
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170 | hits or digi collections of the currently processing event or of |
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171 | previous events. |
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172 | </para> |
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173 | |
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174 | <para> |
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175 | First, you have to get the collection ID number of the hits or |
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176 | digits collection. |
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177 | |
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178 | <informalexample> |
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179 | <programlisting> |
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180 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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181 | G4int myHitsCollID = fDM->GetHitsCollectionID( "hits_collection_name" ); |
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182 | G4int myDigiCollID = fDM->GetDigiCollectionID( "digi_collection_name" ); |
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183 | </programlisting> |
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184 | </informalexample> |
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185 | </para> |
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186 | |
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187 | <para> |
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188 | Then, you can get the pointer to your concrete |
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189 | <emphasis>G4THitsCollection</emphasis> object or |
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190 | <emphasis>G4TDigiCollection</emphasis> object of the currently processing event. |
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191 | |
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192 | <informalexample> |
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193 | <programlisting> |
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194 | MyHitsCollection * HC = fDM->GetHitsCollection( myHitsCollID ); |
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195 | MyDigiCollection * DC = fDM->GetDigiCollection( myDigiCollID ); |
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196 | </programlisting> |
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197 | </informalexample> |
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198 | </para> |
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199 | |
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200 | <para> |
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201 | In case you want to access to the hits or digits collection of |
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202 | previous events, add the second argument. |
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203 | |
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204 | <informalexample> |
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205 | <programlisting> |
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206 | MyHitsCollection * HC = fDM->GetHitsCollection( myHitsCollID, n ); |
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207 | MyDigiCollection * DC = fDM->GetDigiCollection( myDigiCollID, n ); |
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208 | </programlisting> |
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209 | </informalexample> |
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210 | |
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211 | where, <literal>n</literal> indicates the hits or digits collection of the |
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212 | <literal>n</literal><superscript>th</superscript> previous event. |
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213 | </para> |
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214 | |
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215 | </sect2> |
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216 | </sect1> |
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