| 1 | $Id: README,v 1.4 2004/10/27 11:19:13 japost 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 | field03 |
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| 9 | ------- |
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| 10 | |
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| 11 | Example of tracking in magnetic field where field associated |
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| 12 | to selected logical volumes varies. |
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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 which hits the |
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| 36 | absorber perpendicular to the input face. The type of the particle |
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| 37 | and its energy are set in the PrimaryGeneratorAction class, and can |
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| 38 | be changed via the G4 build-in commands of ParticleGun class (see |
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| 39 | the macros provided with this example). |
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| 40 | |
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| 41 | A RUN is a set of events. |
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| 42 | |
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| 43 | 3- DETECTOR RESPONSE |
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| 44 | |
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| 45 | |
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| 46 | A HIT is a record, event per event , of all the |
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| 47 | informations needed to simulate and analyse the detector response. |
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| 48 | |
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| 49 | In this example a CalorHit is defined as a set of 2 informations: |
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| 50 | - the total energy deposit in the absorber, |
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| 51 | - the total tracklength of all charged particles in the absorber, |
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| 52 | |
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| 53 | Therefore the absorber is declared |
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| 54 | 'sensitive detector' (SD), which means they can contribute to the hit. |
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| 55 | |
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| 56 | |
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| 57 | 4- PHYSICS DEMO |
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| 58 | |
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| 59 | The particle's type and the physic processes which will be available |
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| 60 | in this example are set in PhysicsList class. |
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| 61 | |
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| 62 | The messenger classes introduce interactive commands . Using these |
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| 63 | commands the geometry of the detector, the data of the primary |
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| 64 | particle, etc. can be changed. |
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| 65 | |
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| 66 | |
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| 67 | 5- HOW TO START ? |
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| 68 | |
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| 69 | - compile and link to generate an executable |
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| 70 | % cd $G4INSTALL/example/extended/field/field03 |
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| 71 | % gmake |
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| 72 | |
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| 73 | - execute field03 in 'batch' mode from macro files e.g. |
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| 74 | % $(G4INSTALL)/bin/$(G4SYSTEM)/field03 field03.in |
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| 75 | |
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| 76 | - execute field03 in 'interactive' mode with visualization e.g. |
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| 77 | % $(G4INSTALL)/bin/$(G4SYSTEM)/field03 |
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| 78 | .... |
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| 79 | Idle> type your commands |
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| 80 | .... |
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