Re: [fluka-discuss]: proton-proton collisions

From: paola sala <paola.sala_at_cern.ch>
Date: Wed, 20 Apr 2016 12:06:28 +0200

Hello
So, you are indeed simulation colliding beams.
First of all, why do you say that you do not see anything? Of course
there will be no deposited energy in vacuum, but you do have particles
from the primary beam-beam interactions in your usrbdx's. Also, the
particles produced in the beam-beam interactions will not be listed in
the output file as interaction products, since they are considered as
"source" particles.
You will NOT get the results of the USRBDX scoring in the output file,
you have to process them with the provided auxiliary programs or with
FLAIR. Particles are there.

Only, you are simulating the wrong energy, you are running at 1 GeV/c:
the problem is in how you define the PPSOURCE parameters
(as described in section 15 of the user manual, please check!)
- the first card must contain the momenta (GeV/c) of the particle beams.
  The value given in the BEAM card is overridden when you use a special
source. In the BEAM card, you should only give the maximum possible
momentum for initialization of all cross sections.
For 100+100 GeV beams:
SPECSOUR 0.0 0.0 100. 0.0 0.0 -100.PPSOURCE

Then: at LHC energies ( I suppose that 100 GeV was only a test) , you
will need to use the DPMJET generator , as specified in the manual:
Notes:

       1) When SPECSOUR is used to define two colliding beams (SDUM =
PPSOURCE,
          CROSSASY or CROSSSYM), DPMJET must be linked through the script
          $FLUPRO/flutil/ldpmqmd.
          A card PHYSICS with SDUM = LIMITS sets the maximum CMS
momentum (GeV/c)
          in WHAT(1) for DPMJET initialization purposes.

Hope this helps.
On 04/19/2016 03:56 PM, amucha_at_agh.edu.pl wrote:
> Hi,
> Thank you for your answer.
> I tried to obtain the spectrum of particles produced in 100 GeV
> proton- proton interaction by scoring the particles in a vacuum sphere
> (see the input and output files) as you suggested, but it doesn’t
> work. I think that because there are hardly any particle-vacuum
> interactions (except photons and pizeros). When I change the
> material assignment from vacuum to beryllium or lead the results seems
> reasonable, i.e. I can see the energy deposited in the sphere but this
> is not what I wanted for my study.
> So the only way to have particles from proton-proton interaction is
> to obtain them from usrein.f routine? Or am I doing something wrong?
> Regards,
> Agnieszka
>
>
> W dniu 2016-04-12 22:04, Paola Sala napisał(a):
>> Sorry!
>> I gave the wrong routine name! The correct one is
>> usrein.f
>> I apologize
>> Paola
>>> Dear Agnieszka
>>> I see two possibilities:
>>> 1)add a dummy sphere, in vaccum, around the interaction point, and
>>> use it
>>> to score the different particle spectra . For instance with
>>> usrbdx, one
>>> for each particle specie.
>>> 2) dump all the produced particles from a user routine. The best
>>> choice,
>>> in case you are using ppsource, is to use the evvini user routine,
>>> that is
>>> called after the source and gets all the secndaries in the fluka stack
>>> (common FLKSTK )
>>> Regards
>>> Paola
>>>> Hi Fluka Users,
>>>> I'm going to make a new simulation of fluence for one of the silicon
>>>> detector at LHC and compare the results from Fluka and Geant4. My
>>>> first
>>>> problem is how to obtain the four-momenta of particles produced in
>>>> proton-proton collisions in Fluka? At the beginning I want to make a
>>>> comparison at the generation level, so a need a spectrum of all
>>>> particles before they reach any material.
>>>> Cheers,
>>>> Agnieszka
>>>>
>>>> __________________________________________________________________________
>>>>
>>>> You can manage unsubscription from this mailing list at
>>>> https://www.fluka.org/fluka.php?id=acc_info
>>>>
>>>
>>>
>>> Paola Sala
>>> INFN Milano
>>> tel. Milano +39-0250317374
>>> tel. CERN +41-227679148
>>>
>>> __________________________________________________________________________
>>>
>>> You can manage unsubscription from this mailing list at
>>> https://www.fluka.org/fluka.php?id=acc_info
>>>
>>
>>
>> Paola Sala
>> INFN Milano
>> tel. Milano +39-0250317374
>> tel. CERN +41-227679148
>>
>> __________________________________________________________________________
>>
>> You can manage unsubscription from this mailing list at
>> https://www.fluka.org/fluka.php?id=acc_info

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Received on Wed Apr 20 2016 - 13:30:57 CEST

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