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| 2 | ==============================================================
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| 3 | Geant4 - an Object-oriented Toolkit for Simulation HEP
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| 4 | ==============================================================
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| 5 |
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| 6 | Rich Detector for LHCb
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| 7 | ----------------------------------
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| 8 |
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| 9 | This example is intended to simulate the TestBeam Setup of the Rich detector
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| 10 | at the LHCb to test the performance of the aerogel radiator.
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| 11 | The goal of the Rich is the proper identification of charged particles
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| 12 | in a momentum range of 1-150 GeV/c and to assist in the separation of
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| 13 | signal and background.
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| 14 |
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| 15 |
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| 16 | 1. GEOMETRY DEFINITION
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| 17 | -----------------------------
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| 18 |
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| 19 | It consists on 2 detector; RICH1, RICH2 which have to cover
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| 20 | the full LHCb momentum range:
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| 21 |
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| 22 | RICH1: Aerogel 2 to 10 GeV/c
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| 23 | C4F10 < 70 GeV/c
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| 24 |
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| 25 | RICH2: CF4 < 150 GeV/c
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| 26 |
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| 27 |
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| 28 | The geometry (defined inside RichDetectorConstruction class) consists of
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| 29 | 4 Hpd, a target containing the aerogel and a spherical mirror.
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| 30 | The TestbeamSetUp is related to changes in teils, distances between elements
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| 31 | of the testbeam and types. All the possible configurations are considered
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| 32 | by a loop inside the MaterialParameters class.
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| 33 |
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| 34 |
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| 35 | 2. AN EVENT: THE PRIMARY GENERATOR
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| 36 | -------------------------------------
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| 37 |
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| 38 | The primary kinematic consists of a single charge particle (normally pions)
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| 39 | which is sent towards the target producing a rain of photons reflected and
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| 40 | focused by the spherical mirrors and recolected after in the Hpd.
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| 41 |
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| 42 | The aim of the testbeam is to perform resolutions measurements with
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| 43 | and without the aerogel to probe the improvement of its use. Comparisons
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| 44 | between simulation and data are performed to determine the angle defined
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| 45 | between the simmetry axis of the system (axis z) and the distance to the
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| 46 | interaction point of the produced photons in the Hpd.
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| 47 |
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| 48 | The information related to type of particles to be sent, their energy
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| 49 | and directions is included inside the PrimaryGeneratorAction class.
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| 50 | These parameters can be changed interactively using an extern macro
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| 51 | (run1.mac). It is recomended the use of such macro for changes because
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| 52 | it avoids further compilations.
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| 53 |
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| 54 | A RUN is a set of events.
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| 55 |
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| 56 |
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| 57 | 3. VISUALIZATION
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| 58 | --------------------
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| 59 |
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| 60 | The Visualization manager is set in the main().
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| 61 | The Initialisation of the drawing is already defined in run1.mac.
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| 62 | The example is prepared to use any other visualization packages which
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| 63 | can be defined in such macro or inside RichTbVis0.mac. Before running
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| 64 | the events, the visualization must be initialized by:
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| 65 |
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| 66 | > /control/execute/RichTbVis0.mac
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| 67 |
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| 68 | The detector has longitudinal view of the geometry as default.
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| 69 |
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| 70 | The tracks are drawn at the end of event, and erased at the end of the run.
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| 71 |
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| 72 |
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| 73 | 4. PHYSICS DEMO
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| 74 | ----------------
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| 75 |
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| 76 | The particles type and physics processes which will be available in
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| 77 | this example are set in PhysicsList class.
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| 78 |
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| 79 | In addition a built-in interactive command (process/inactivate proname)
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| 80 | allows to activate/inactivatethe processes one by one.
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| 81 |
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| 82 | 5. HOW TO START?
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| 83 | -----------------
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| 84 |
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| 85 | - compile and link to generate an executable
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| 86 | % cd geant4/examples/advanced/Rich/
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| 87 | % gmake
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| 88 |
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| 89 | - execute the program in 'batch' mode from macro files
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| 90 | % RichTbSim run1.mac
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| 91 |
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| 92 | - execute tests in 'interactive mode'
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| 93 | % RichTbSim
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| 94 | .....
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| 95 |
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| 96 | Idle> type your commands
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| 97 | .....
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| 98 | Idle> exit
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| 99 |
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| 100 |
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| 101 | 6. HISTOGRAMS
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| 102 | ---------------
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| 103 |
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| 104 | This example produces 7 histograms (saved as rich.his generated automatically
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| 105 | during the running time) which illustrate the final state of the most important
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| 106 | information of the example:
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| 107 |
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| 108 | histo1 --> Number of Photon Hits per Track
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| 109 | histo2 --> Number of Photons before Mirror
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| 110 | histo3 --> WaveLength of Photons before Mirror
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| 111 | histo4 --> WaveLength of Photons after Mirror
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| 112 | histo5 --> Cherekov Angle at roduction all angles
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| 113 | histo6 --> Z of the Photon Emission Point
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| 114 | histo7 --> Cherenkov Ring Radius
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| 115 |
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| 116 | See their definition on AnalysisManager.
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| 117 |
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| 118 | Note that histograms are disabled via the flag G4ANALYSIS_USE in GNUmakefile.
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| 119 |
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| 120 |
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| 121 | 7. Using the PI implementation of the AIDA histograms:
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| 122 | ------------------------------------------------------
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| 123 |
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| 124 | In order to setup the proper environmental variables, needed for
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| 125 | running AIDA / PI , run the script:
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| 126 |
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| 127 | --- For c-shell : source setupAidaPi.csh
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| 128 |
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| 129 | --- For bash-shell : . setupAidaPi.sh
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| 130 |
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| 131 | Notice that you need g++ 3.2 or 3.23.
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| 132 |
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