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None Different energy loss in two method  

Forum: Analysis
Date: 31 May, 2012
From: Kavita Lalwani <Kavita Lalwani>

Hi G4users,

I was trying to calculate energy loss of proton in water phantom (it is sphere of diameter 230mm) using two different method.

First method:

if(fTrack->GetVolume()->GetName() == "water"){
totEdepwater += fStep->GetTotalEnergyDeposit() / MeV;//calculate total deposited energy in phantom
 }

Second method: Using entry and exit point in G4stepPoint, like below

 G4StepPoint* point1 = fStep->GetPreStepPoint();
 G4StepPoint* point2 = fStep->GetPostStepPoint();

 if(fTrack->GetVolume()->GetName() == "water"){
   if (point1->GetStepStatus() ==fGeomBoundary){ 
      Ek_in_water = fTrack->GetKineticEnergy() / MeV;//calculate kinetic energy at entry point of phantom
       }

 if (point2->GetStepStatus() == fGeomBoundary){
     analysis->Ek_out_water = fTrack->GetKineticEnergy() / MeV;//calculate kinetic energy at exit point of phantom
     }
 Eloss_water = Ek_in_water -Ek_out_water;	        

}

Then I am plotting these variables in histograms event by event.

Using two method, I am getting different distributions for energy loss in water phantom.

I have attached plots for energy loss (for 1k and one event) using two method and verbose output (for one event). You can have a look via comments "Ek_in_water" and "Ek_out_water".

Please suggest where I am wrong?

Brief description: Beam: proton pencil beam, KE: 200 MeV Geometry: Two fibers before water phantom and two after phantom to measure the incoming and outgoing position of proton and at the end, a calorimeter made up of 100 layers of scintillators to measure the energy of outgoing proton.

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2012/05/31/05.02-93457-ElossEdep.pdf
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2012/05/31/05.02-29179-OUTPUT.text

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1 None: Re: Different energy loss in two method   (Kavita Lalwani - 31 May, 2012)
(_ None: Re: Different energy loss in two method   (Kavita Lalwani - 31 May, 2012)
(_ None: Re: Different energy loss in two method   (Tsukasa Aso - 31 May, 2012)
(_ None: Re: Different energy loss in two method   (Kavita Lalwani - 04 Jun, 2012)
(_ None: Re: Different energy loss in two method   (Tsukasa Aso - 05 Jun, 2012)
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