|Message: Problem with muons hit position inside the sensitive volume||Not Logged In (login)|
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I want to perform a simulation detecting muons in a gas volume. The goal is to register all the energy deposits to be able to reconstruct the muon track. As first simple example I define a gas box volume (x = y = 50 cm; z = 1 cm centred at x = y = 0 cm) and I throw negative muons of fixed energy (12 GeV) and direction (0,0,1), i.e. perpendicular to the gas-box x-y surface. When I register the output, the energy deposit as well as the x and y position of the hits seem to be correct. This is not the case for the z coordinate. A clear excess of hits appears at the end of the gas-box volume in the z-coordinate (see attached plot together with the x and y distributions of the hits, which seem normal) The way I store the hit position (x,y,z) is the following: G4ThreeVector hitpos = aStep->GetPostStepPoint()->GetPosition(); Among the different tests I performed, I observed the same effect: - Changing the gas volume thickness (z) up to 100 cm - Changing the material of my sensitive box (using the G4_POLYSTYRENE material) - Using a muon energy distribution and not mono-energetic ones as well as changing the generation point - Using different physics lists (the Geant4 standard and theG4EmLivermorePhysics for example) Anybody knows what could be the origin of this behaviour and the way to solve it? Thank you very much in advance! Attachment: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/12/06/07.59-95942-HitXPos.png http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/12/06/07.59-4086-HitYPos.png http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/12/06/07.59-42587-HitZPos.png
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