From: Anna Ferrari <anna.ferrari_at_lnf.infn.it>

Date: Sun, 16 Jan 2011 18:07:23 +0100 (CET)

Date: Sun, 16 Jan 2011 18:07:23 +0100 (CET)

Dear Anna,

good that you find the mistake!

Just to clarify a bit more: absorbed dose is the energy deposited by

ionizing radiation per mass unit and 1 Gy of absorbed energy means 1J

deposited in 1 Kg of matter. To have the relation with the deposited

energy per unit volume (usually expressed in the convenient units GeV/cm3)

you have then to multiply by material density remembering to convert

Joules in GeV through the relation you wrote (1 GeV = 1.602 E-10 J)

1Gy (= 1 J/Kg) = E10/1.602 GeV/Kg = (E7/1.602) rho[g/cm3] GeV/cm3

and then as you find in the manual 1.602 E-7/rho is the coefficient to

pass from energy deposition in GeV/cm3 to absorbed energy in Gy.

Remeber also that all the results are per primary weigth.

kind regards,

Anna

PS: the first time in your calculation in rad you forgot a factor E3

coming from Kg->g...

*> Dear Anna,
*

*> sorry, I found my mistake.
*

*>
*

*> Best regards
*

*> Anna Kiseleva
*

*>
*

Dear Anna,

I try to understand the relation between different dimensions. In FLUKA

manual there is:

"Energy deposition will be expressed in GeV per cm3 per unit primary

weight. To obtain doses (in Gy per unit primary weight), the results must

be multiplied by (1.602176462E-7 / rho), where rho is the material density

in g/cm3."

But if I try to go from GeV/cm3 to Gy, I get different coefficient:

1 GeV =3D 1E9 eV = 1.6E-10 J -> 1 J = 1E10/1.6 GeV

1 Gy = 1 J/kg = 1E10/1.6 GeV/kg = 1E10/1.6 GeV/(1E3 g) * cm3/cm3 =

1E7/1.6/rho GeV/cm3

It means, I need to multiply GeV/cm3 by 1E7/1.6/rho in order to have Gy.

Please, correct my, but I don't understand, how this number

1.602176462E-7 / rho was calculate?

Best regards

Anna Kiseleva

*>
*

*> -----Ursprüngliche Nachricht-----
*

*> Von: owner-fluka-discuss_at_mi.infn.it im Auftrag von Anna Ferrari
*

*> Gesendet: So 16.01.2011 04:36
*

*> An: Kiseleva, Anna
*

*> Cc: fluka-discuss_at_fluka.org
*

*> Betreff: Re: From energy density in GeV/cm3 to rad
*

*>
*

*>
*

*> Dear Anna,
*

*>
*

*> first of all: in the SI, the International System of Units, the unit for
*

*> the absorbed dose (and not the energy density) is the Gray (Gy) and not
*

*> the rad. The use of the old unit rad ( = 10 mGy) is then discouraged.
*

*>
*

*> Said that, I have the impression that if you express the material density
*

*> in g/cm3 your relation does not work... please check.
*

*>
*

*> Kind regards,
*

*>
*

*> Anna
*

*>
*

*>> Dear FLUKA developers,
*

*>>
*

*>> I have questions.
*

*>> I try arithmetically to recalculate energy density in rad:
*

*>> 1 rad = 1e8/1.6022/(material density) GeV/cm3
*

*>> But I got so big numbers if I calculate it for gas (argon). It is right?
*

*>> And how I can compare these numbers with dose in rad?
*

*>>
*

*>> Best regards
*

*>> Anna Kiseleva
*

*>>
*

*>> E-mail: A.Kiseleva_at_gsi.de
*

*>> CBM
*

*>> Gesellschaft fur Schwerionenforschung mbH
*

*>> Planckstrasse 1,
*

*>> D-64291 Darmstadt
*

*>>
*

*>>
*

*>
*

*>
*

*>
*

Received on Sun Jan 16 2011 - 19:57:25 CET

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