RE: what is the relation between yield and cross section?

Hi Jinghantao,

in one case you score the double differential distribution of the
outgoing particles, whereas in the in the other you obtain the
double-differential cross section. As you correctly indicate both scale
by number of incoming particles, the density and the target length. What
concerns your question, if I understand correctly, the 'scaling' between
the two scorings is nothing else then the differential cross section
itself: d2N/dx1dx2 * sigma =3D d2sigma/dx1dx2 -> does this answer your
question?

cheers

Markus

> -----Original Message-----
> From: owner-fluka-discuss@mi.infn.it [mailto:owner-fluka-
> discuss@mi.infn.it] On Behalf Of jinghantao
> Sent: 31 August 2008 15:48
> To: fluka-discuss@fluka.org
> Subject: what is the relation between yield and cross section?
>=20
> Hello everyone,
>=20
> As beginner, I want to re-calculate some processes in paper of
> =A1=B0Treating High Energy Showers=A1=B1(downloaded from fluka site). =
I use
> the USRYIELD card to
> recalculate the double differential spectra(Figure 26 and Figure 28
> in paper).
> In continuation card, for WHAT(6), ixa=3D1. So i can obatain the
> double-differential cross section
> d^2 sigma/d x1 d x2, Then I use usysuw to read the data out from the
> binary files. The energy-spectra
> shade of curves for deferent degree is very similar to Figure 28, but
> the order of magnitude is not right.
> Then I set ixa=3D3 to calculate double differential yield d^2 N/ d x1 =
d
> x2.
> I find the ratio of d^2 N/dx1 dx2 to d^2 sigma/dx1 dx2 is just a
> constant.
> Generally, the relation is d^2 N/ d x1 d x2 =3D (d^2 sigma/dx1
> dx2)*(L*rho)/mA,
> where the L is the target thickness, rho the nuclear density and mA
> the target-nucleus mass.
> If I firstly calculated the yield and multipled by (L*rho)/mA, I
> find the rusults are correct.
> What is the constant between d^2 N/dx1 dx2 (ixa=3D3) and d^2 sigma/dx1
> dx2 (ixa=3D1) in fluka?
> Thank you very much in advance.
>=20
> Sincerely yours,
> =A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1jinghantao
> =A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1jinght@mail.ihep.ac.cn =
2008-08-31
>=20
Received on Sat Sep 6 15:10:56 2008