Re: [fluka-discuss]: low energy (E < 1 MeV) heavy-ion transport

From: Stefan Roesler <sroesler_at_mail.cern.ch>
Date: Mon, 8 Feb 2016 09:07:11 +0100

Dear Rob

Please note that the transport threshold per nucleon for HEAVYION is fixed
to that of 4-HELIUM, i.e. you will have to set PART-THR for the latter.

Thus, I suggest to set
PART-THR -1.E-6 4-HELIUM

which will give you 250 eV/n for heavy ions.

Please also note that there is a typo in your option MULSOPT.

Please let us know whether this solves your problem.

Cheers
Stefan


On Wed, 3 Feb 2016, Robert Bark wrote:

> Dear FLUKA experts
>
> I am presently trying to simulate a detector capable of detecting heavy-ions
> (190 < A < 240) of low energy ( 0.1 < E < 2) MeV.
>
> The heavy-ions are the recoiling reaction products (thalium isotopes) of a 62
> MeV alpha beam on a thin gold target.
> The target thickness is 9e-6 cm. In the simulation, the target is actually
> divided into 3 regions, each of 3e-6cm thickness. The target has to be thin
> to allow the Tl recoils to escape out of the target and be detected by a
> down-stream detector.
>
> It is important to know the energy distribution of the reaction products to
> simulate the detector operation.
>
> Here is the problem:
>
> The energy distribution (scored with either USRBDX or USRYIELD) of the
> reaction products does not change across the boundaries of the 3 target
> layers, nor do any of the reactions products fail to escape the target. The
> FLUKA energy distributions agree with what one can calculate analytically for
> a fusion evaporation reaction.
>
> This means there is no energy loss of the recoils in the target in the FLUKA
> simulation. This contradicts both experiment and SRIM simulations, where a
> few 100 keV is expected to be lost.
>
> So far I have used the FLUKA default (PRECISION) and have also tried adding
> the cards:
>
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8....+....9
> IONTRANS HEAVYION
> PART-THR -1E-05 HEAVYION HEAVYION 0.0
> MULOPT 1. 1. 1. GLOBAL
>
> to no success.
>
> Can anybody advise on the correct input for *low-energy* heavy-ion transport?
>
> Best Regards
> Rob
>
> --
> Dr Robert Bark
> Leader, Radioactive Ion Beam Project
> iThemba LABS
> www.tlabs.ac.za
>
> tel: 021 843 1123
> fax: 021 843 3525
>
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Received on Mon Feb 08 2016 - 10:35:13 CET

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