# AW: From energy density in GeV/cm3 to rad

From: Kiseleva, Anna <A.Kiseleva_at_gsi.de>
Date: Sun, 16 Jan 2011 10:47:47 +0100

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

-----Urspr=FCngliche Nachricht-----
Von: Anna Ferrari [mailto:anna.ferrari_at_lnf.infn.it]
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 ( =3D 10 mGy) is then discouraged.

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

Kind regards,

Anna

> Dear FLUKA developers,
>
> I have questions.
> I try arithmetically to recalculate energy density in rad:
> 1 rad =3D 1e8/1.6022/(material density) GeV/cm3
> But I got so big numbers if I calculate it for gas (argon). It isright?
> 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,