[1208] | 1 | <HTML> |
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| 2 | <TITLE> |
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| 3 | </TITLE> |
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| 4 | <!-- Changed by: Katsuya Amako, 21-Sep-1998 --> |
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| 5 | <!-- Changed by: Dennis Wright, 27-Nov-2001 --> |
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| 6 | <!-- Proof read by: Joe Chuma, 30-Jun-1999 --> |
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| 7 | |
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| 8 | <BODY> |
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| 9 | <TABLE WIDTH="100%"><TR> |
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| 10 | <TD> |
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| 11 | |
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| 12 | |
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| 13 | <A HREF="index.html"> |
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| 14 | <IMG SRC="../../../../resources/html/IconsGIF/Contents.gif" ALT="Contents"></A> |
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| 15 | <A HREF="hit.html"> |
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| 16 | <IMG SRC="../../../../resources/html/IconsGIF/Previous.gif" ALT="Previous"></A> |
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| 17 | <A HREF="persistency.html"> |
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| 18 | <IMG SRC="../../../../resources/html/IconsGIF/Next.gif" ALT="Next"></A> |
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| 19 | </TD> |
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| 20 | <TD ALIGN="Right"> |
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| 21 | <FONT SIZE="-1" COLOR="#238E23"> |
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| 22 | <B>Geant4 User's Guide</B> |
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| 23 | <BR> |
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| 24 | <B>For Application Developers</B> |
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| 25 | <BR> |
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| 26 | <B>Detector Definition and Response</B> |
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| 27 | </FONT> |
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| 28 | </TD> |
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| 29 | </TR></TABLE> |
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| 30 | <BR><BR> |
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| 31 | |
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| 32 | <P ALIGN="Center"> |
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| 33 | <FONT SIZE="+3" COLOR="#238E23"> |
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| 34 | <B>4.5 Digitization</B> |
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| 35 | </FONT> |
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| 36 | <BR><BR> |
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| 37 | |
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| 38 | <HR ALIGN="Center" SIZE="7%"> |
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| 39 | <p> |
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| 40 | |
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| 41 | <a name="4.5.1"> |
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| 42 | <H2>4.5.1 Digi</H2></a> |
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| 43 | |
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| 44 | A hit is created by a sensitive detector when a step goes through |
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| 45 | it. Thus, the sensitive detector is associated to the corresponding |
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| 46 | <i>G4LogicalVolume</i> object(s). On the other hand, a digit is |
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| 47 | created using information of hits and/or other digits by a digitizer |
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| 48 | module. The digitizer module is not associated with any volume, and |
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| 49 | you have to implicitly invoke the <tt>Digitize()</tt> method of your |
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| 50 | concrete <i>G4VDigitizerModule</i> class. |
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| 51 | <p> |
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| 52 | Typical usages of digitizer module include: |
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| 53 | <ul> |
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| 54 | <li>simulate ADC and/or TDC |
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| 55 | <li>simulate readout scheme |
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| 56 | <li>generate raw data |
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| 57 | <li>simulate trigger logics |
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| 58 | <li>simulate pile up |
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| 59 | </ul> |
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| 60 | <p> |
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| 61 | |
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| 62 | <B><i>G4VDigi</i></B> |
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| 63 | <P> |
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| 64 | <i>G4VDigi</i> is an abstract base class which represents a digit. |
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| 65 | You have to inherit this base class and derive your own concrete |
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| 66 | digit class(es). The member data of your concrete digit class |
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| 67 | should be defined by yourself. <i>G4VDigi</i> has two virtual methods, |
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| 68 | <tt>Draw()</tt> and <tt>Print()</tt>. |
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| 69 | <p> |
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| 70 | |
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| 71 | <B><i>G4TDigiCollection</i></B> |
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| 72 | <P> |
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| 73 | <i>G4TDigiCollection</i> is a template class for digits collections, |
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| 74 | which is derived from the abstract base class <i>G4VDigiCollection</i>. |
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| 75 | <i>G4Event</i> has a <i>G4DCofThisEvent</i> object, which is a |
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| 76 | container class of collections of digits. The usages of <i>G4VDigi</i> |
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| 77 | and <i>G4TDigiCollection</i> are almost the same as <i>G4VHit</i> and |
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| 78 | <i>G4THitsCollection</i>, respectively, explained in the previous |
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| 79 | section. |
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| 80 | <p> |
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| 81 | |
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| 82 | <HR> |
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| 83 | <a name="4.5.2"> |
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| 84 | <H2>4.5.2 Digitizer module</H2></a> |
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| 85 | |
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| 86 | <B><i>G4VDigitizerModule</i></B> |
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| 87 | <P> |
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| 88 | <i>G4VDigitizerModule</i> is an abstract base class which represents |
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| 89 | a digitizer module. It has a pure virtual method, <tt>Digitize()</tt>. |
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| 90 | A concrete digitizer module must have an implementation of this |
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| 91 | virtual method. The Geant4 kernel classes do not have a ``built-in'' invocation to |
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| 92 | the <tt>Digitize()</tt> method. You have to implement your code to invoke |
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| 93 | this method of your digitizer module. |
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| 94 | <p> |
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| 95 | In the <tt>Digitize()</tt> method, you construct your <i>G4VDigi</i> |
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| 96 | concrete class objects and store them to your <i>G4TDigiCollection</i> |
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| 97 | concrete class object(s). Your collection(s) should be associated |
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| 98 | with the <i>G4DCofThisEvent</i> object. |
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| 99 | <p> |
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| 100 | |
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| 101 | <B><i>G4DigiManager</i></B> |
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| 102 | <P> |
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| 103 | <i>G4DigiManager</i> is the singleton manager class of the digitizer |
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| 104 | modules. All of your concrete digitizer modules should be registered |
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| 105 | to <i>G4DigiManager</i> with their unique names. |
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| 106 | <pre> |
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| 107 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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| 108 | MyDigitizer * myDM = new MyDigitizer( "/myDet/myCal/myEMdigiMod" ); |
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| 109 | fDM->AddNewModule(myDM); |
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| 110 | </pre> |
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| 111 | Your concrete digitizer module can be accessed from your code using |
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| 112 | the unique module name. |
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| 113 | <pre> |
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| 114 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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| 115 | MyDigitizer * myDM = fDM->FindDigitizerModule( "/myDet/myCal/myEMdigiMod" ); |
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| 116 | myDM->Digitize(); |
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| 117 | </pre> |
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| 118 | Also, <i>G4DigiManager</i> has a <i>Digitize()</i> method which takes |
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| 119 | the unique module name. |
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| 120 | <pre> |
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| 121 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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| 122 | MyDigitizer * myDM = fDM->Digitize( "/myDet/myCal/myEMdigiMod" ); |
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| 123 | </pre> |
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| 124 | <p> |
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| 125 | |
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| 126 | <B>How to get hitsCollection and/or digiCollection</B> |
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| 127 | <P> |
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| 128 | <i>G4DigiManager</i> has the following methods to access to the |
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| 129 | hits or digi collections of the currently processing event |
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| 130 | or of previous events. |
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| 131 | <p> |
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| 132 | First, you have to get the collection ID number of the hits or digits |
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| 133 | collection. |
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| 134 | <pre> |
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| 135 | G4DigiManager * fDM = G4DigiManager::GetDMpointer(); |
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| 136 | G4int myHitsCollID = fDM->GetHitsCollectionID( "hits_collection_name" ); |
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| 137 | G4int myDigiCollID = fDM->GetDigiCollectionID( "digi_collection_name" ); |
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| 138 | </pre> |
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| 139 | Then, you can get the pointer to your concrete <i>G4THitsCollection</i> |
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| 140 | object or <i>G4TDigiCollection</i> object of the currently processing |
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| 141 | event. |
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| 142 | <pre> |
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| 143 | MyHitsCollection * HC = fDM->GetHitsCollection( myHitsCollID ); |
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| 144 | MyDigiCollection * DC = fDM->GetDigiCollection( myDigiCollID ); |
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| 145 | </pre> |
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| 146 | In case you want to access to the hits or digits collection of previous |
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| 147 | events, add the second argument. |
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| 148 | <pre> |
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| 149 | MyHitsCollection * HC = fDM->GetHitsCollection( myHitsCollID, n ); |
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| 150 | MyDigiCollection * DC = fDM->GetDigiCollection( myDigiCollID, n ); |
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| 151 | </pre> |
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| 152 | where, <tt>n</tt> indicates the hits or digits collection of the <tt>n</tt><sup>th</sup> |
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| 153 | previous event. |
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| 154 | <p> |
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| 155 | |
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| 156 | <BR><BR> |
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| 157 | <HR> |
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| 158 | <A HREF="../../../../Authors/html/subjectsToAuthors.html"> |
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| 159 | <I>About the authors</I></A> |
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| 160 | |
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| 161 | </BODY> |
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| 162 | </HTML> |
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