Re: Residual nuclei in spallation reaction protons on Pb/Bi, and in particular light nuclei

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Tue, 1 Jun 2010 14:34:55 +0200

Dear Luca,

the higher yields you observe for tritium and alphas come from the PEANUT
and evaporation developments implemented in the 2008 release.
Bertini/Dresner models turn out to significantly underestimate
experimental findings, as you can see in the attached excitation functions
where the two top curves refer to He4 and He3 production in iron, whereas
the new FLUKA values are in quite better agreement with data. For He3
production on heavy elements, we think that the predicted values are still
too low. For tritium we have not yet at hand a dedicated benchmarking.

Ciao

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

On Mon, 24 May 2010, Zanini Luca wrote:

>
>
> Dear All,
>
> I have run the residual nuclei production in the MEGAPIE target using
FLUKA 2008.3, and compared with our previous results with FLUKA2006.3b.
> We are now finishing an article that compares the measured noble gases
during the MEGAPIE irradiation with the calculated ones, and I thought it
would be better to include that latest FLUKA predictions.
>
> This is a spallation reaction of 575 MeV protons on a Pb/Bi target.
>
> You can see in the attached figure the two mass distributions.
> As you can see they are very similar, and in general noble gases and
mercury isotopes (which were also measured) compare well (most of the
values within 20-30%).
>
> My question is about the He4 and tritium production. Here I get very
different results:
> For He4, I now get 0.4 atoms/proton (with FLUKA2006 it was 0.11
atoms/proton). I would like to understand this factor of 4, given the
importance of this isotope.
>
> For tritium, I now get 0.130 atoms/proton (before it was 0.073). The
FLUKA2008 value seems too high, considering also that MCNPX 2.5.0 (with
Bertini/Dresner) gives 0.05, in better agreement with the old FLUKA value.
>
> On the contrary, for hydrogen we get exactly the same value.
>
> Any reason that explains the differences for He4 and H3?
>
> I used in both cases the same input files, and I believe (unless I made
some mistakes..) that I linked correctly to rQMD. The physics options are
listed below.
>
> Thank you very much in advance,
> Luca
>
> <<fig.jpg>>
>
>
> GLOBAL 1.0
> *AAAAAAAXX_________|_________|_________|_________|_________|_________|
> DEFAULTS EET/TRAN
> BEAM -0.575 0.0 0.0 1.0PROTON
> BEAMPOS 0.0 0.0 -19.0 0.0 0.0
> SOURCE -19.
> EMF
> PHYSICS 3.0 EVAPORAT
> PHYSICS 1.0 COALESCE
> PHYSICS 0.05 DPMTHRES
> PHYSICS 0.05 QMDTHRES
> EVENTYPE 2. DPMJET
>
>
>

Received on Fri Jun 04 2010 - 00:25:56 CEST

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