RE: Differences in neutron + proton spectra between Fluka/DPMJET v Phojet 1.12

From: Anton Lechner <>
Date: Mon, 6 Aug 2012 08:02:41 +0000

Dear Paul,

The origin of the differences you observe between standalone Phojet 1.12
and FLUKA/DPMJET-III pp collision products is twofold:

First, when generating pp collisions with SPECSOUR in the DPMJET energy
range you need to provide in addition the PHYSICS cards with SDUM=LIMITS
and WHAT(1) set to a value "larger than one half of the centre-of-mass energy"
(quote from the slides from the 2010 FLUKA course in Portugal).
When applying this card the agreement between Phojet 1.12 and FLUKA/DPMJET-III

However, even with the PHYSICS card a discrepancy still remains which can
be explained by fragmentation parameters which have been modified in DPMJET-III
for tuning of AA collisions (thanks to Stefan Roesler for clarifying this point!). The
version you are using is rather old and parameters have evolved over time.

I hope this answers your question (despite the very late answer).

Cheers, Anton

From: [] on behalf of Paul Miyagawa []
Sent: 25 June 2012 13:27
Subject: Differences in neutron + proton spectra between Fluka/DPMJET v Phojet 1.12


I am generating 7 TeV pp collisions in Fluka using the SPECSOUR card and
the flukadpm3 executable (compiled using ldpmqmd), and comparing the particle
spectra with events generated using standalone Phojet 1.12 (fed into Fluka using source.f).
I see differences in the normalisation for neutron and proton spectra between
the two (attached plots are for 50000 collisions each). For other particles
(charged pions, photons, electrons, muons) I get reasonable agreement.
Can anyone explain why these differences would occur? Thanks for any assistance.

Received on Mon Aug 06 2012 - 10:43:27 CEST

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