1 | $Id: README,v 1.5 2010/09/08 11:22:01 vnivanch 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 | TestEm8 |
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9 | ------- |
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10 | |
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11 | Example for investigation of ionisation in thin absorbers and gaseous |
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12 | detectors |
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13 | |
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14 | 1- GEOMETRY DEFINITION |
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15 | |
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16 | The target is a cilinder made of a given material placed inside |
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17 | cilindrical container, which is placed inside the world volume. |
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18 | |
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19 | Following parameters define the geometry: |
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20 | - the material of the target, |
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21 | - the thickness of the target, |
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22 | - the radius of the target, |
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23 | - the material of the container, |
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24 | - the thickness of the container, |
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25 | - the material of the world. |
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26 | |
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27 | The list of materials used in gaseous detectors are built inside |
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28 | the DetectorConstruction class, also NIST materials are availabe. |
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29 | The default geometry is provided but all parameters can be changed via |
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30 | UI commands defined in the DetectorMessenger class, for example, |
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31 | |
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32 | /testem/setGasMat XeCH4C3H8 |
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33 | /testem/setWindowMat G4_MYLAR |
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34 | /testem/setWorldMat G4_AIR |
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35 | /testem/setGasThick 10 cm |
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36 | /testem/setGasRad 20 cm |
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37 | /testem/setWindowThick 50 um |
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38 | |
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39 | |
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40 | 2- AN EVENT : THE PRIMARY GENERATOR |
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41 | |
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42 | The primary kinematic consists of a single particle which hits the |
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43 | absorber perpendicular to the input face. The type of the particle |
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44 | and its energy can be set via the G4 build-in commands of ParticleGun |
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45 | A RUN is a set of events. |
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46 | |
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47 | 3- DETECTOR RESPONSE |
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48 | |
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49 | The TargetSD class sending information about each step inside the target |
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50 | to the HistoManager class scoring of energy deposition in the detector. |
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51 | Additionally at each step of a particle inside the target the number of |
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52 | ionisation clusters is sampled using G4ElectronIonPair helper class. The |
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53 | parameter of transformation of energy into ionisation clusters can be |
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54 | set via UI command: |
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55 | |
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56 | /testem/setPairEnergy 19 eV |
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57 | |
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58 | |
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59 | 4- PHYSICS |
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60 | |
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61 | The particle's type and the physic processes which will be available |
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62 | in this example are set in PhysicsList class, which uses Geant4 |
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63 | EM physics constructors providing in the physics_list library. |
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64 | |
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65 | The messenger classes introduce interactive commands. In particular, |
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66 | PAI ionisation model can be added using G4EmConfurator helper class, |
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67 | which is invokated by the UI command |
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68 | |
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69 | /testem/phys/addPhysics pai |
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70 | |
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71 | 5- HOW TO START ? |
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72 | |
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73 | - compile and link to generate an executable |
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74 | % cd TestEm8 |
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75 | % gmake |
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76 | |
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77 | - execute TestEm8 in 'batch' mode from macro files e.g. |
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78 | % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8 TestEm8.in |
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79 | |
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80 | - execute TestEm8 in 'interactive' mode with visualization e.g. |
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81 | % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8 |
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82 | .... |
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83 | Idle> type your commands |
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84 | .... |
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85 | |
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86 | |
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87 | |
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88 | |
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