Re: EMFCUT: production thresholds overrides transport thresholds

From: Alberto Fasso' <>
Date: Thu, 21 Apr 2011 20:05:52 +0200

To all users on the discussion list:

It was I who suggested to George to ask that question on the production and
transport thresholds, because I did not know the answer myself. In the
I have contacted privately Alfredo Ferrari and I got the answer.

It is not a bug: the slide 7 of the lecture on Ionization and Transport
of the
last FLUKA course, that George cited, was referring to heavy particles only,
not to electrons. For electrons, it is not possible to have a production
threshold higher than the transport threshold: when this happens, the
program modifies the transport threshold making it equal to the production
It is different for protons, muons and other heavy charged particles:
for them the production threshold (set by the DELTARAY command) can be
higher than the transport threshold (set by PART-THR), and the transport
below the delta-ray threshold is done by unrestricted dE/dx and ionization

The reason for this difference is that in Moller scattering it is not
possible, after the scattering, to distinguish the incoming electron from
the produced electron. And even in Bhabha scattering by positrons, it
can happen that the secondary electron gets more energy than the
incoming positron.

I will add this information in the manual.


On Wed, 20 Apr 2011, George Kharashvili wrote:

> Dear FLUKA experts,
> It appears that the production thresholds set by EMFCUT with PROD-CUT
> sdum override the transport thresholds set by EMFCUT with blank sdum.
> For example, if production cuts are set to 3 MeV for e-, e+ and photons,
> and transport cuts are set to 2 MeV, the output file shows that Ae, Ap,
> Ecut, and Pcut were ALL taken to be 3 MeV (as is happens in case of the
> attached input).
> However, the manual (EMFCUT) and slide 7 of the lecture on Ionization
> and Transport of the last FLUKA course suggest that when the production
> threshold is higher than the transport threshold, particles with
> energies between the two thresholds are still transported and loose
> energy by dE/dx.
> Could this be a bug in the code?
> I noticed that FLUKA-2008 was doing the same.
> Best regards,
> - George
Received on Thu Apr 21 2011 - 22:34:34 CEST

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