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Question Dose Normalization 

Forum: Space Applications
Date: 06 Oct, 2014
From: Leonardo Ghizoni <Leonardo Ghizoni>

Hello Experts,

I'm having some difficulties when trying to normalize my outputs, like the Total Dose.

First I'm running with a simple geometry: a spherical target sorrounded by a spherical shell with 2mm thickness.

To compute the dose, I'm using the primitive scorer G4PSDoseDeposit and using GPS as the source.

I took a look at a ppt document of G. Santin about normalization, and as I understood, the "real world" Dose is calculated as:

Dr = Nr*Ds/Ns,

where Nr is the number of particles in the real world, Ds is the dose calculated in the simulation and Ns is the number of events simulated, right?

Now, the "real world" number of particles Nr is calculated by the flux. That's where I'm a little confused. I do have the fluxes as functions of the energy, in a table calculated by Spenvis and the respective macro created. As I understad, the number Nr is calculated by:

Nr = flux * 4*pi^2*r^2.

I don't know which flux to use, since I have a table based on energies. And the radius is defined by me on the source, right? I defined the source like this:

/gps/particle proton

/gps/ene/type Arb

/gps/hist/type arb

/gps/hist/point 1.000000E-01 2.407800E+01

/gps/hist/point 1.500000E-01 2.397600E+01

/gps/hist/point 2.000000E-01 1.974300E+01

/gps/hist/point 3.000000E-01 1.135400E+01

/gps/hist/point 4.000000E-01 1.059100E+01

/gps/hist/point 5.000000E-01 9.840100E+00

/gps/hist/point 6.000000E-01 1.154300E+01

/gps/hist/point 7.000000E-01 1.277300E+01

/gps/hist/point 1.000000E+00 8.546000E+00

/gps/hist/point 1.500000E+00 3.924800E+00

/gps/hist/point 2.000000E+00 3.838800E+00

/gps/hist/point 3.000000E+00 3.667500E+00

/gps/hist/point 4.000000E+00 3.831800E+00

/gps/hist/point 5.000000E+00 3.993600E+00

/gps/hist/point 6.000000E+00 4.341400E+00

/gps/hist/point 7.000000E+00 4.587900E+00

/gps/hist/point 1.000000E+01 3.820900E+00

/gps/hist/point 1.500000E+01 2.932800E+00

/gps/hist/point 2.000000E+01 2.538000E+00

/gps/hist/point 3.000000E+01 2.066400E+00

/gps/hist/point 4.000000E+01 1.757500E+00

/gps/hist/point 5.000000E+01 1.592800E+00

/gps/hist/point 6.000000E+01 1.462600E+00

/gps/hist/point 7.000000E+01 1.370200E+00

/gps/hist/point 1.000000E+02 1.118000E+00

/gps/hist/point 1.500000E+02 7.635400E-01

/gps/hist/point 2.000000E+02 4.962900E-01

/gps/hist/point 3.000000E+02 2.196200E-01

/gps/hist/point 4.000000E+02 2.586700E-02

/gps/hist/inter Spline

/gps/pos/type Surface

/gps/pos/shape Sphere

/gps/pos/centre 0. 0. 0. mm

/gps/pos/radius 9 mm

/gps/ang/type cos

/gps/ang/mintheta 0.000E+00 deg

/gps/ang/maxtheta 9.000E+01 deg


So, my radius will be 9mm.

Finally, my normalized dose changes values when I change the number of primary events...this sounds incorret, since I'm normalizing it.

I know I'm doing it wrong, just don't know where.

Please help? I'm really having a hard time on this.

Thank you in advance.

Best Regards, Leonardo.

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