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Question Tracking in a UnionSolid 

Forum: Event and Track Management
Date: 01 Jan, 2014
From: Rafayel Paremuzyan <Rafayel Paremuzyan>

Dear users, Happy New 2014 Year!

My problem is the following:
I have an LH2 target which has a cylindrical form and end-cap part is a half-sphere.
I implemented it using G4UnionSolid, and the connection part is shown
in the first attachment. 

During simulation Z vertexes of generated particles "particleGun->SetParticlePosition(x, y, z)" are
distributed all over the target length, whereas x and y are 0 (centre).

The strange thing to me is that, it seems that particles which were produced inside the cylinder do interact inside the whole 
target volume, whereas particles (electrons and photons around 1-3 GeV) that are produced in the end-cap part doesn't interact at all 
with the target material. this is also illustrated in a first attachment, with two vertexes one is in the cylinder part of the
target, and one can see points (yellow) where e- and gamma leave the volume of target, whereas particles that are produced inside the
spherical part of the target, doesn't show any kind of interaction.

The 2nd figure is also favour to this conclusion,
where shown generated - reconstructed energy as a, function of z coordinate, where one can see a step-like drop at z=5.5 cm.
Energy loss is not completely 0 for z>5.5 because I have another materials that particles pass through.
 
Just in case, I also put the part of the code which creates and places the target

  G4Tubs *target_LH2_tube = new G4Tubs("target_LH2_tube", 0, target_LH2_radius, target_LH2_tube_length/2., 0, 360.*degree);
  G4Sphere *target_LH2_endcup = new G4Sphere("target_LH2_endcup", 0, target_LH2_radius, 0., 360.*degree, 0., 90.*degree);
  G4UnionSolid *target_LH2_solid = new G4UnionSolid("target_LH2_solid", target_LH2_tube, target_LH2_endcup, 0, 
						    G4ThreeVector(0, 0, 0.999*(target_LH2_tube_length/2.)));
  LH2_target_log = new G4LogicalVolume(target_LH2_solid, LH2_mat, "LH2_target_log");
  LH2_target_phys = new G4PVPlacement(0, G4ThreeVector(0., 0., target_LH2_tube_center - 0.5*target_LH2_radius), LH2_target_log, "LH2_target_phys", Vac_scat_chamber_log,
   				      true, 0, true);


Rafo


   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/01/01/19.27-21647-Target_Endcup.gif
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/01/01/19.24-87135-dE_vz.gif

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1 Feedback: Re: Tracking in a UnionSolid   (Gumplinger Peter - 08 Jan, 2014)
(_ Question: Re: Tracking in a UnionSolid   (Rafayel Paremuzyan - 08 Jan, 2014)
(_ Feedback: Re: Tracking in a UnionSolid   (Gumplinger Peter - 08 Jan, 2014)
(_ Feedback: Re: Tracking in a UnionSolid   (Rafayel Paremuzyan - 09 Jan, 2014)
(_ Feedback: Re: Tracking in a UnionSolid   (Gumplinger Peter - 09 Jan, 2014)
(_ Feedback: Re: Tracking in a UnionSolid   (Rafayel Paremuzyan - 09 Jan, 2014)
(_ Disagree: Re: Tracking in a UnionSolid   (Gumplinger Peter - 10 Jan, 2014)
(_ Feedback: Re: Tracking in a UnionSolid   (Rafayel Paremuzyan - 11 Jan, 2014)
(_ Ok: Re: Tracking in a UnionSolid   (Rafayel Paremuzyan - 16 Jan, 2014)
(_ Disagree: Re: Tracking in a UnionSolid   (Gumplinger Peter - 16 Jan, 2014)
(_ Agree: Re: Tracking in a UnionSolid   (Gumplinger Peter - 16 Jan, 2014)
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