# Re: residue nuclei for thin target (fwd)

From: Alberto Fasso' (fasso@SLAC.Stanford.EDU)
Date: Tue Mar 04 2008 - 00:31:19 CET

• Next message: Sebastien WURTH: "Re: deq99c.f & dose equivalent"

Dear Harphool,

first, a recommendation to you and to all FLUKA users: please don't write
privately to me or to any of my colleagues, but keep all correspondence and
discussion on the fluka-discuss list. Everybody must be able to participate
in the discussion, not only you and me. And maybe somebody else is more

Coming to your question: of course you get a very high cross section. You
are getting residual nuclei not from the primary protons only, but from all
the secondaries. A 10 cm thick target is not a "thin" target! Check at the
end of your xxx.out file: how many secondary particles are produced?
Make your target 0.01 cm thick, and decrease accordingly the WHAT(2)=20
parameter in LAM-BIAS to something like 1.E-5 or 1.E-6.

How to calculate the cross section?
The number of residual nuclei of one type per primary, R, is given by:
R =3D N s d
where
s =3D cross section
N =3D number of atoms per cm3 =3D Av * rho / A
(Avogadro's number * density / mass number: Ns is the so-called
macroscopic cross section, which gives the probability of interaction
per unit length)
d =3D foil thickness
therefore

s =3D R/(Nd)

Alberto

> Date: Mon, 3 Mar 2008 01:08:31 -0800 (PST)
> From: harphool kumawat <kumawat77@yahoo.com>
> To: Alberto Fasso' <fasso@slac.stanford.edu>
> Subject: Re: residue nuclei for thin target
>
> Dear Alberto,
> Please see the attached file and output data.
> to get the value in cross-section.
> I have used 1870mb for Pb+1GeV proton reaction but then the
> values from FLUKA goes very high. Most probably I am making
> some mistake. Please correct me.
> Best regards,
> Harphool
>
> Alberto Fasso' <fasso@slac.stanford.edu> wrote:
> Dear Harphool,
>
> describe a thin target, and increase as you wish the number of interactio=
ns=20
> in
> the target by means of two commands LAM-BIAS, the first with SDUM =3D bla=
nk
> and WHAT(2) < 1, the second with SDUM =3D INEPRI.
> See the detailed description of LAM-BIAS in the manual.
>
> Alberto
>
>
> On Thu, 21 Feb 2008, harphool kumawat wrote:
>
>> Dear all,
>> May I ask you to suggest, how to calculate the residual nuclei for the
>> thin targets? I wanted to calculate GSI data for Inverse kinematics
>> or other thin target experimental data.
>> Thanking you,
>> Harphool
>
>

--=20
Alberto Fass=F2
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762 Fax: (1 650) 926 3569
fasso@slac.stanford.edu
--1334196310-408197497-1204587079=3D:26811--

• Next message: Sebastien WURTH: "Re: deq99c.f & dose equivalent"

This archive was generated by hypermail 2.1.6 : Tue Mar 04 2008 - 09:27:29 CET