Re: NIEL Dimension

From: Alberto Fasso' <fasso_at_SLAC.Stanford.EDU>
Date: Thu, 26 May 2011 07:33:27 -0700 (PDT)

Mojdeh,

NIEL is a kind of restricted stopping power: non-ionizing energy deposited
per unit length. If one multiplies NIEL by a particle track length, one
gets the non-ionizing energy deposited by that particle along its track.

NIEL-DEP in FLUKA (generalized particle 238) is just an amount of
deposited energy (the fraction of deposited energy which is not deposited
by ionization) and therefore is expressed in GeV. When calculated with
USRBIN, the total score is normalized per cm3 per primary weight, and
therefore is expressed in GeV/cm3.

In the literature, you can find NIEL expressed in energy (MeV or keV) per
g/cm2 (as for stopping power), or in MeVmb. In the latter case, it means
energy lost per atom/mb: number of atoms/mb = atoms/cm2 x cm2/mb, where
cm2/mb = 1.E-27.
If you multiply MeVmb by (1.E-27 N rho/A), where N = Avogadro's number,
A = mass number, rho = density in g/cm3, you get MeV cm2/g.

So, it is not exact what you write, that "In the FLUKA Manual was written
GeV as a NIEL dimension". GeV is the dimension of NIEL-DEP, which is NIEL
multiplied by fluence. FLUKA does not score NIEL, but NIEL-DEP.

Alberto

On Wed, 25 May 2011, mojdeh najm wrote:

> Dear FLUKA Experts and users
> In the FLUKA Manual was written GeV as a NIEL dimension but in the
> other references NIEL is define [MeV cm2/g]. How can I relate and
> interpret NIEL resulted by FLUKA to other refrence? [NIEL = 95 MeVmb]
> Please guide me.
> Sincerely yours
> Mojdeh Najm
Received on Thu May 26 2011 - 17:05:09 CEST

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