Re: Documentation on SPECSOUR

From: Stefan Roesler <>
Date: Wed, 1 Aug 2012 20:24:38 +0200

Dear Samuel

The cross sections for non-elastic processes are calculated by DPMJET
during initialization and the particle production processes (e.g., various
diffractive processes) are simulated accordingly. Only relative
probabilities for certain processes matter in the FLUKA simulations of LHC
collisions and, thus, I think cross section values (in mb) are not printed

If they are of interest, you could run DPMJET standalone where cross
sections are listed in the output. Note that the inelastic cross section
predicted by DPMJET for LHC energies is somewhat higher (10-15%) than
measured by CMS/ATLAS. However, as only relative probabilities matter this
discrepancy has no impact on the simulation in FLUKA. Thus, depending on
your problem, it could be better to use the measured value for overall

The Glauber cross sections that you quote are not obtained with DPMJET.


On Wed, 1 Aug 2012, Francesco Cerutti wrote:

> Dear Samuel
> assuming that you are using DPMJET3 through FLUKA (and not its standalone
> version which has a larger scope) and in particular to generate colliding
> (LHC p/Pb) beam products by the SPECSOUR option, I confirm that you miss the
> elastic contribution and also - for Pb, where it's dominant - the
> electromagnetic dissociation one. The latter is indeed independently
> available in FLUKA, but not for collisions at source level (SPECSOUR) in the
> distributed version. On the other hand, we recently included it in our
> development version enabling the code to sample either EMD events simulated
> by the native FLUKA model or inelastic events simulated by DPMJET3, according
> to the respective cross sections (450barn vs 7.8barn for 2.76TeV/n Pb-Pb).
> Therefore it will become public with new release.
> Coming back to the FLUKA-DPMJET processes, inelastic events include
> diffractive ones, and the peak in your proton spectrum is indeed diffractive.
> What matters for the normalization of such results, is then the corresponding
> cross-section, which for p-p at 7TeV centre-of-mass is around 73mb.
> Stefan may want to comment on differential cross-sections as a function of
> the impact parameter.
> Best
> Francesco
> **************************************************
> Francesco Cerutti
> CH-1211 Geneva 23
> Switzerland
> tel. ++41 22 7678962
> fax ++41 22 7668854
> On Wed, 1 Aug 2012, Samuel Hedges wrote:
>> Dear Stefan Roesler,
>> I am using FLUKA to characterize the response of a luminosity monitor
>> to pp and heavy-ion collisions, and had a few questions after seeing
>> your post. I'm trying to understand which cross sections DPMJET uses
>> for collisions. Francesco had mentioned that DPMJET doesn't simulate
>> electromagnetic dissociations for heavy ion collisions. Are the only
>> interactions for these collisions inelastic? I ask because we thought
>> we saw an elastic peak near the beam energy in the attached graph:
>> I found a publication on DPMJET that states "Gribov-Glauber multiple
>> scattering formalism...allows the calculation of total, elastic,
>> quasi-elastic, and production cross sections for any high-energy
>> nuclear collision."
>> ( I
>> was hoping you might be able to help clarify which types of
>> interactions DPMJET simulates and the cross sections it uses.
>> I found Glauber cross sections for some of the collisions I am running
>> here: Are these the cross
>> sections that are used by DPMJET?
>> I appreciate your help. Thank you,
>> Samuel Hedges
>> On Sun, Jun 10, 2012 at 1:59 PM, Stefan Roesler <>
>> wrote:
>>> Hi Paul
>>> The event-generator is DPMJET-III; please don't forget to link it with
>>> ldpmqmd. It simulates inelastic (including diffractive) events. Elastic
>>> pp scattering is not treated. You can find more info on DPMJET in the
>>> respective literature.
>>> In order to score particles emerging directly from the pp collisions I
>>> suggest that define a small sphere (region) around the interaction point
>>> and score at this new boundary with any of the usual scorings (USRBDX,
>>> Cheers
>>> Stefan
>>> On Sun, 10 Jun 2012, Paul Miyagawa wrote:
>>>> Hello,
>>>> I would like to try using proton-proton collisions using the SPECSOUR
>>>> card below. However, I haven't managed to find any documentation on the
>>>> actual physics behind it (e.g., generator, cross-section, what
>>>> processes, in particular elastic scattering?, DPMJET?). How can I get
>>>> more information about the generated events before the detector
>>>> simulation? Thanks for any suggestions.
>>>> SPECSOUR 0.0 0.0 4000.9382 0.0
>>>> 0.0-4000.9382PPSOURCE
>>>> Regards,
>>>> Paul
Received on Thu Aug 02 2012 - 00:32:26 CEST

This archive was generated by hypermail 2.2.0 : Thu Aug 02 2012 - 00:32:27 CEST