Warning, /geant4/examples/extended/exoticphysics/channeling/ch3/README is written in an unsupported language. File is not indexed.
0001 -------------------------------------------------------------------
0002
0003 =========================================================
0004 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0005 =========================================================
0006
0007 Example ch3
0008 -----------
0009 A. Sytov
0010 INFN Ferrara Division, sytov@fe.infn.it
0011
0012 INTRODUCTION
0013 Example ch3 demonstrates the minimum requirements necessary to integrate the
0014 G4CoherentPairProduction process into a project, along with the G4ChannelingFastSimModel
0015 and G4BaierKatkov models, to simulate the physics of electromagnetic showers in
0016 an oriented crystal.
0017
0018 The key concept is the acceleration of electromagnetic processes (both radiation and
0019 pair production) in an oriented crystal, which can significantly reduce the effective
0020 radiation length [1,2]. Potential applications include electron/positron sources for
0021 accelerator experiments, as well as crystalline oriented calorimeters for collider and
0022 space applications [1,2].
0023
0024 This example serves as a guideline for users on how to add this physics
0025 to their existing Geant4 projects. It includes the minimum necessary options
0026 to incorporate this physics. Specifically, it requires registering
0027 G4FastSimulationPhysics and G4CoherentPairProductionPhysics in the main routine and
0028 adding a few lines of code in DetectorConstruction.
0029
0030 All of this physics does not depend on the physics list. In particular, the
0031 process G4CoherentPairProduction simulates only coherent part of pair production in
0032 the crystal volume, while the incoherent one should be simulated with
0033 standard Geant4 processes.
0034
0035 DESCRIPTION
0036
0037 The example simulates high energy photon interaction (typically above 10 GeV) with
0038 an oriented W crystal with <111> crystal axes aligned along the photon beam direction.
0039
0040 The structure of this example is very similar to the example ch1.
0041 ch3 includes a straight W crystal and a detector positioned behind it.
0042 The incoming photon beam is set up in macro run.mac.
0043
0044 One can also use the Geant4 GUI by launching the code without specifying a macro file.
0045 In this case, the visualization setup is automatically loaded through the vis.mac and
0046 init_vis.mac macro files. The initial beam distribution in this setup will be identical
0047 to that in run.mac.
0048
0049 The example does not include any input of the model or geometry parameters
0050 from the macro to keep it as straightforward as possible. The output is recorded
0051 into the file results.root. It consists of the spectrums of e-, e+
0052 and gamma arriving to the detector. To build these plots, one has to
0053 open this file in root and use Spectrum_electrons->Draw(), Spectrum_positrons->Draw()
0054 and Spectrum_gamma->Draw() for e-, e+ and gamma, respectively.
0055
0056 REFERENCES
0057 [1] V. N. Baier, V. M. Katkov, V. M. Strakhovenko, Electromagnetic Processes
0058 at High Energies in Oriented Single Crystals (World Scientific, Singapore, 1998).
0059 [2] L. Bandiera, V.V. Tikhomirov et al. Phys. Rev. Lett. 121, 021603 (2018).
