1 | $Id: README,v 1.5 2010/06/06 04:55:22 perl Exp $ |
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2 | ------------------------------------------------------------------- |
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3 | |
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4 | ========================================================= |
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5 | Geant4 - an Object-Oriented Toolkit for Simulation in HEP |
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6 | ========================================================= |
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7 | |
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8 | field01 |
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9 | ------- |
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10 | |
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11 | Example enabling investigation of tracking in a magnetic field. |
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12 | Electromagnetic processes also included. |
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13 | |
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14 | |
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15 | 1- GEOMETRY DEFINITION |
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16 | |
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17 | The "absorber" is a solid made of a given material. |
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18 | |
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19 | Three parameters define the absorber : |
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20 | - the material of the absorber, |
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21 | - the thickness of an absorber, |
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22 | - the transverse size of the absorber (the input face is a square). |
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23 | |
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24 | The volume "World" contains the "absorber". |
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25 | In this test the parameters of the "World" can be changed , too. |
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26 | |
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27 | In addition a transverse uniform magnetic field can be applied. |
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28 | |
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29 | The default geometry is constructed in DetectorConstruction class, |
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30 | but all the parameters can be changed via |
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31 | the commands defined in the DetectorMessenger class. |
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32 | |
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33 | 2- AN EVENT : THE PRIMARY GENERATOR |
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34 | |
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35 | The primary kinematic consists of a single particle (proton, Ekin = 1 GeV) |
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36 | which hits the |
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37 | absorber perpendicular to the input face. The type of the particle |
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38 | and its energy are set in the PrimaryGeneratorAction class, and can |
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39 | be changed via the G4 build-in commands of ParticleGun class (see |
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40 | the macros provided with this example). |
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41 | |
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42 | A RUN is a set of events. |
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43 | |
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44 | 3- DETECTOR RESPONSE |
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45 | |
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46 | The spatial distribution of charged particles transported in magnetic |
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47 | field is envistigated. |
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48 | A HIT is a record, event per event , of all the |
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49 | informations needed to simulate and analyse the detector response. |
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50 | |
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51 | In this example a CalorHit is defined as a set of 2 informations: |
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52 | - the total energy deposit in the absorber, |
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53 | - the total tracklength of all charged particles in the absorber, |
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54 | |
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55 | Therefore the absorber is declared |
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56 | 'sensitive detector' (SD), which means they can contribute to the hit. |
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57 | |
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58 | 4- PHYSICS DEMO |
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59 | |
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60 | The particle's type and the physic processes which will be available |
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61 | in this example are set in PhysicsList class. |
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62 | |
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63 | The messenger classes introduce interactive commands . Using these |
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64 | commands the geometry of the detector, the data of the primary |
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65 | particle, etc. can be changed. |
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66 | |
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67 | |
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68 | 5- HOW TO START ? |
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69 | |
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70 | - compile and link to generate an executable |
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71 | % cd $G4INSTALL/example/extended/field/field01 |
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72 | % gmake |
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73 | |
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74 | - execute field01 in 'batch' mode from macro file e.g. |
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75 | % $(G4INSTALL)/bin/$(G4SYSTEM)/field01 field01.in |
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76 | |
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77 | - execute field01 in 'interactive' mode with visualization e.g. |
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78 | % $(G4INSTALL)/bin/$(G4SYSTEM)/field01 |
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79 | .... |
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80 | Idle> /control/execute vis.mac |
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81 | .... |
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82 | |
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83 | |
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84 | |
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