Re: [fluka-discuss]: How to find kinetic energy of particle after degrader?

From: Giuseppe Battistoni <>
Date: Wed, 20 Jan 2016 15:45:13 +0100

Dear Helga
from your input I see that you have not specified a default.
If this is so you are probably using the
NEW-DEFA (our present default of defaults) which means 10 MeV threshold
for charged particles.
What is probably occurring is that you have just the calculation
of the average energy loss, which would be the same for all particles.

In you case, having 5 MeV of kinetic energy, you should use at minimum
the PRECISIO default
You also need to set EMFCUT for production and transport
electron/positron thresholds, to set DELTARAY cuts accordingly
etc. etc.

                Giuseppe Battistoni

On 20/01/16 15:34, Helga Holmestad wrote:
> Thanks a lot for the two answers. I have now tried to use both the USRTRACK and modifying the BXDRAW in mgdraw.f.
> I have tried to run the program with 10 primary particles, what is strange is that I always get the same energy loss in my degrader. I am of course expecting to get a distribution. I guess I am doing something wrong with the seed to the random generator. I have attached the inputfile and I am running the program with the command:
> $FLUPRO/flutil/rfluka -e exe -N0 -M1 exam2.inp
> Dear Helga,
> I think you can just simply define a very small region behind your degrader and use and USRTRACK score for this region. Or you can use USRBDX to score the energy of your particle go from your degrader region to outside region.
> Kind.
> ________________________________________
> From: Giuseppe Battistoni []
> Sent: 18 January 2016 15:39
> To: Helga Holmestad;
> Subject: Re: [fluka-discuss]: How to find kinetic energy of particle after degrader?
> Dear Helga
> the simplest solution is actually a pre-defined scoring:
> you should make use of a USRBDX to score the energy distribution of
> protons at the boundary between the degrader and a further
> downstream region that you can easily define. One-way current
> of fluence scoring.
> About of mgdraw:
> the us of USDRAW is in any case a wrong choice, since it gives you
> access to what occurred in an interaction inside the
> degrader region, but the energy loss in the material before exiting
> the degrader has not yet been taken into account.
> The correct entry point in mgdraw.f would be BXDRAW at the boundary that
> is of your interest, as the one I mentioned before, but this would
> eventually give the same results of USRBDX.
> Giuseppe Battistoni
> On 18/01/16 15:06, Helga Holmestad wrote:
>> Dear FLUKA experts
>> I have a simple setup in my simulation, a beam of 5.3 MeV protons is in
>> vacuum and is sent trough a 50 um aliminium degrader. I need to know the
>> energy of the particles after it has passed the degrader. I don't see
>> any predefined scoring options for this, or is there? Or do I need to
>> use the collision tape?
>> I have attempted to write my own mgdraw and using the USDRAW routine for
>> this. The variable tki(i) should give the energy of the particle. But
>> the USDRAW function is never called in my simulation, because it looks
>> like energy loss is not considered as an interaction.
> --
> INFN Milano
> via Celoria 16, 20133 Milano
> tel: +39 02 50317307
> fax: +39 02 50317617

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Received on Wed Jan 20 2016 - 16:58:49 CET

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