Gabriele Cosmo
133 lines
4.2 KiB
Plaintext
133 lines
4.2 KiB
Plaintext
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==============================================================
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Geant4 - an Object-oriented Toolkit for Simulation HEP
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==============================================================
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Rich Detector for LHCb
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----------------------------------
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This example is intended to simulate the TestBeam Setup of the Rich detector
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at the LHCb to test the performance of the aerogel radiator.
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The goal of the Rich is the proper identification of charged particles
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in a momentum range of 1-150 GeV/c and to assist in the separation of
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signal and background.
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1. GEOMETRY DEFINITION
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-----------------------------
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It consists on 2 detector; RICH1, RICH2 which have to cover
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the full LHCb momentum range:
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RICH1: Aerogel 2 to 10 GeV/c
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C4F10 < 70 GeV/c
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RICH2: CF4 < 150 GeV/c
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The geometry (defined inside RichDetectorConstruction class) consists of
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4 Hpd, a target containing the aerogel and a spherical mirror.
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The TestbeamSetUp is related to changes in teils, distances between elements
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of the testbeam and types. All the possible configurations are considered
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by a loop inside the MaterialParameters class.
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2. AN EVENT: THE PRIMARY GENERATOR
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-------------------------------------
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The primary kinematic consists of a single charge particle (normally pions)
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which is sent towards the target producing a rain of photons reflected and
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focused by the spherical mirrors and recolected after in the Hpd.
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The aim of the testbeam is to perform resolutions measurements with
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and without the aerogel to probe the improvement of its use. Comparisons
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between simulation and data are performed to determine the angle defined
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between the simmetry axis of the system (axis z) and the distance to the
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interaction point of the produced photons in the Hpd.
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The information related to type of particles to be sent, their energy
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and directions is included inside the PrimaryGeneratorAction class.
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These parameters can be changed interactively using an extern macro
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(run1.mac). It is recomended the use of such macro for changes because
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it avoids further compilations.
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A RUN is a set of events.
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3. VISUALIZATION
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--------------------
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The Visualization manager is set in the main().
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The Initialisation of the drawing is already defined in run1.mac.
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The example is prepared to use any other visualization packages which
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can be defined in such macro or inside RichTbVis0.mac. Before running
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the events, the visualization must be initialized by:
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> /control/execute/RichTbVis0.mac
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The detector has longitudinal view of the geometry as default.
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The tracks are drawn at the end of event, and erased at the end of the run.
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4. PHYSICS DEMO
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----------------
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The particles type and physics processes which will be available in
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this example are set in PhysicsList class.
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In addition a built-in interactive command (process/inactivate proname)
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allows to activate/inactivatethe processes one by one.
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5. HOW TO START?
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-----------------
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- compile and link to generate an executable
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% cd geant4/examples/advanced/Rich/
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% gmake
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- execute the program in 'batch' mode from macro files
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% RichTbSim run1.mac
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- execute tests in 'interactive mode'
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% RichTbSim
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.....
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Idle> type your commands
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.....
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Idle> exit
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6. HISTOGRAMS
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---------------
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This example produces 7 histograms (saved as rich.his generated automatically
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during the running time) which illustrate the final state of the most important
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information of the example:
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histo1 --> Number of Photon Hits per Track
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histo2 --> Number of Photons before Mirror
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histo3 --> WaveLength of Photons before Mirror
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histo4 --> WaveLength of Photons after Mirror
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histo5 --> Cherekov Angle at roduction all angles
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histo6 --> Z of the Photon Emission Point
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histo7 --> Cherenkov Ring Radius
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See their definition on AnalysisManager.
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Note that histograms are disabled via the flag G4ANALYSIS_USE in GNUmakefile.
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7. Using the PI implementation of the AIDA histograms:
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------------------------------------------------------
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In order to setup the proper environmental variables, needed for
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running AIDA / PI , run the script:
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--- For c-shell : source setupAidaPi.csh
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--- For bash-shell : . setupAidaPi.sh
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Notice that you need g++ 3.2 or 3.23.
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