RE: [fluka-discuss]: RE: Antiproton annihilation in materials

From: Helga Holmestad <helga.holmestad_at_cern.ch>
Date: Thu, 7 Dec 2017 17:11:09 +0000

Hi
I reply now to the answer to my very old question since it became relevant for me again.

About nucleaon/antinucleon annihilation:
Can you point out which experimental results FLUKA is adjusted for? Is it also based upon some theoretical models?

Is also the annihilation in different materials adjusted to experimental data? From LEAR[1] there exist data of annihilations in Carbon and Calium. Fluka does not reproduce exactly these results, but is not to far away

[1]W. Markiel, H. Daniel, T. Von Egidy, F.J. Hartmann, P. Hofmann, W. Kanert, H.S.
Plendl, K. Ziock, R. Marshall, H. Machner, G. Riepe, and J.J. Reidy. Emission of
helium ions after antiproton annihilation in nuclei. Nuclear Physics A, 485(3):445
460, 1988.


________________________________________
From: Paola Sala [paola.sala_at_mi.infn.it]
Sent: 10 November 2014 12:45
To: Helga Holmestad
Cc: fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: RE: Antiproton annihilation in materials

Dear Helga,

About antinucleon annihilation:

- The basic antinucleon-nucleon process is modeled through the
  production and decay of two or more intermediate states whose branchings
  are adjusted to reproduce experimental pion/kaon/resonances
multiplicities.

- In nuclei, all nuclear effects (density, Fermi motion, Pauli, reinteraction
  of secondaries...) are treated by the PEANUT model as for all other
  hadronic interactions

- Annihilations occur at shallow depths inside the nucleus. The depth
  is chosen as a function of the atomic number, the interaction being more
  and more pheripheral as the nuclear mass increases.

- In case of compounds, the relative annihilation probabilities are
  calculated following Ponomarev Annu.Rev.Nucl. Sci. 23 395 (1973) for
  hydrogenated compounds, and Daniel Phys Rev Letters 35, 1649 (1975)
  for other compounds
Regards
Paola

> Thanks a lot for the help I got to sort out the mistake in my simulations,
> when I did everything right there is no large discrepancy between data and
> simulations.l
> I am still very interested in finding the answer to my first question:
>
> - What are the models used to simulate antiproton annihilation in
> different material? Where can I find more information about this?
>
> Hope
> ________________________________
> From: Helga Holmestad
> Sent: 27 October 2014 12:09
> To: fluka-discuss_at_fluka.org
> Subject: Antiproton annihilation in materials
>
> Dear experts
>
>
> I am working in the AEgIS collaboration with simulations of detectors for
> low energy anti-protons. This autumn we are going to have a testbeam with
> the timepix3 detector which gives us an opportunity to study antiproton
> annihilation in materials. Therefore I am very interested in how FLUKA
> does annihilation of anti-protons especially in silicon, but also other
> materials. I have some questions I hope you are could answer me:
>
> - What are the models used to simulate antiproton annihilation in
> different material? Where can I find more information about this.
> - How is the models tested against data? I see very little data on
> antiproton annihilation, it is mainly LEAR data. In the table below I have
> compared some of the LEAR data to FLUKA simulations. It looks almost
> reasonable for everything else than protons. Is there an explanation for
> the discrepancy? I have also attached the article that this data is taken
> from (see table 5)
>
>
> Table showing the multiplicity of fragments from 100 annihilation in
> Carbon12.
>
> Particle Energy range(MeV) LEAR
> FLUKA
> proton 6-18 23.3+-2.0
> 61.57+-8.94
> deteron 8-24 9.3 +-0.8
> 16.87+-1.29
> triton 11-29 4.5+-0.4
> 4.70+-0.17
> helium3 36-70 1.72+-0.17
> 0.54+-0.01
> alpha 36-70 1.14+-0.12
> 1.54+-0.01
>
>
> I have used the latest version of FLUKA which had some updates when it
> came to annihilation
>
> Kind regards,
>
> Helga
>
>
>
>


Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148


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Received on Thu Dec 07 2017 - 19:34:01 CET

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