[904] | 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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