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Question A question on Unit in example rdecay01 

Forum: Documentation and Examples
Date: 22 Dec, 2011
From: Clare Huang <Clare Huang>

Hi all,

how's it going?! this may be an elementary question, but i was wondering if anyone can help me to straighten out the units in the example rdecay01 using geant4.9.4.p02.

In the source code RunAction.cc where the activity is calculated and printed out, the code is shown below...

===============/rdecay01/src/RunAction.cc=====================================
.
.
.
.
 G4double molMass = particle->GetAtomicMass()*g/mole;
 G4double nAtoms = Avogadro/molMass;
 G4double ActivPerAtom = 1./Tmean;
 G4double ActivPerMass = ActivPerAtom*nAtoms;

 G4cout << "molMass = " << molMass << G4endl;
 G4cout << "\n nAtoms = " << std::setw(wid) << nAtoms << G4endl;
 G4cout << "Tmean = " << Tmean << " nano second (10-9 seconds)" << G4endl;
 G4cout << "ActivPerAtom = " << ActivPerAtom << G4endl;
 G4cout << "ActivPerMass = " << ActivPerMass << G4endl;
 G4cout << "\n Activity = "
            << std::setw(wid) << ActivPerMass*g/becquerel
	    << " Bq/g   ("    << ActivPerMass*g/curie
	    << " Ci/g) \n" 
	    << G4endl;
.
.
===========================================================================

the code compiled and I tested this code by executing Co60.mac (with /run/beamOn 1000) in the example. In order to understand what each variable mean, I printed out the number that each variable represents and here they are..

molMass = 3.745e+23 ==> I thought atomic mass of the particle is in the unit of gram. For Co-60,the atomic mass should be close to 60 g/mole. But this number represents 60*6.242e21 for some reason. Why is there a 6.242e21 in this variable?

nAtoms = 1.608 Tmean = 2.399e+17 ==> I believe it's in nano second ActivPerAtom = 4.169e-18 ActivPerMass = 6.703e-18

Activity is caluclated as ActivPerMass*g/becquerel. again, there is a 6.242e30 constant to get the activity level printed below

Activity = 4.184e+13 Bq/g (1131 Ci/g)

can someone explain why? thanks a lot for your time and help in advance!

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1 None: Re: A question on Unit in example rdecay01   (michel maire - 23 Dec, 2011)
2 None: Re: A question on Unit in example rdecay01   (michel maire - 25 Dec, 2011)
1 None: Re: A question on Unit in example rdecay01   (Clare Huang - 25 Dec, 2011)
(_ None: Re: A question on Unit in example rdecay01   (michel maire - 26 Dec, 2011)
(_ None: Re: A question on Unit in example rdecay01   (Clare Huang - 02 Jan, 2012)
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