Re: AW: AW: Energy deposition

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Thu, 27 Jan 2011 12:35:24 +0100

Dear Beatrice,

meaningless negative energy deposition values and infinite statistical
errors just come from the fact that your USRBIN energy detectors are
associated to ... undefined cooling times: you input 8 cooling times and
you ask over the range 13-22.

But I would like to point out a more fundamental misunderstanding. You
have to bear in mind the distinction between prompt and decay radiation,
being the latter generated by the (late=not instantaneous) decay of the
radioactive nuclei produced by the first.
If you search - as usually - for prompt energy deposition values (indeed
expressed in GeV/cm3 per beam proton), then irradiation profile and decay
times are totally unrelevant. You do not need to ask FLUKA to perform the
radioisotope decay (no need for RADDECAY) and you have to rescale the
results by the beam current, getting instantaneous power density at
any time during irradiation.
On the other hand, by associating the USRBIN energy scoring to a given
cooling time (referred to the input irradiation profile), you will
directly get the power density at that time (in GeV/(cm3*s)) *only due to
the decay (electromagnetic) radiation*.

Ciao

Francesco

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

On Thu, 27 Jan 2011, beatrice pomaro wrote:

> Dear Dr. Sommerer,
> I disabled the Sternheimer and
> Mat-prop card associated to Material UC2, however
> I get the same negative energy deposition results
> and INF values. The error messages you noticed
> before (me too), are not anymore after disabling the cards, as you confirm.
> But is there another problem in my input file,
> then? I wonder if it is correct to activate RADDECAY with its default
> values?
> Sorry, to ask again
>
> Thank you,
> Beatrice
>
>
> At 18.29 26/01/2011, Sommerer, Florian wrote:
>> Dear Beatrice,
>>
>> When rerunning your simulation I found the
>> following lines written in the out and err file:
>>
>>
>> *** dp/dx:d,imat,ztar,ij,po,eo -0.00179035082 31 34.6662384 1 0.572616202
>> 1.09920164 ***
>> *** x,xoster,ccster,d0ster -0.214465268 -0.2191 -6.0247 0. ***
>> *** dp/dx:d,imat,ztar,ij,po,eo -0.0134390424 31 34.6662384 1 0.618808585
>> 1.12395685 ***
>> *** x,xoster,ccster,d0ster -0.18077257 -0.2191 -6.0247 0. ***
>> *** dp/dx:d,imat,ztar,ij,po,eo -0.0225896654 31 34.6662384 1 0.668727261
>> 1.15219403 ***
>> ***
>>
>> Did you observe the same?
>> I could be wrong but in my opinion these lines
>> indicate a serious problem in the initialisation
>> of the stopping power for Uranium dicarbide.
>> That might be the reason for the negative values in the energy deposition.
>>
>> You are using Sternheimer parameters and you are
>> assigning the ionization potential for Uranium
>> dicarbide according to the values that are
>> available in the flair data base. This is the recommended way to do it.
>> However I think exactly there is the problem.
>> When I omit Sternheimer values and ionization
>> potential and run again, I don't get the error
>> messages any more. I think the transport will
>> still be reasonable without these parameters.
>>
>>
>>
>> Cheers, Florian
>>
>>
>>
>>
>>
>>
>> --
>> Dipl.-Ing. Dr. techn. Florian Sommerer
>> Physiker
>> Radiologische Klinik / Heidelberger Ionenstrahl-Therapiezentrum
>> Florian.Sommerer_at_med.uni-heidelberg.de
>> Im Neuenheimer Feld 450
>> 69120 Heidelberg
>> Germany
>> -----Urspr=FCngliche Nachricht-----
>> Von: beatrice pomaro [mailto:pomaro_at_dic.unipd.it]
>> Gesendet: Mittwoch, 26. Januar 2011 17:14
>> An: Sommerer, Florian
>> Betreff: Re: AW: Energy deposition
>>
>> Dear Dr. Sommerer,
>> I had the same problem but I run
>> flupix-2010 and, by reducing the number of
>> binning, I had no more problems of stopping because of memory.
>> I give in attachment the same input file, with
>> less binning (I kept results requirement after
>> 1hour, 1year, 10years and 50years from t0,
>> suitably converted into seconds from the end of
>> radiation profile), but I have the same problem
>> of negative values and INF values for energ
>> deposition (I put, in addition, just the USRBIN34 results).
>> Many thanks for the support,
>>
>> Sincerely,
>> Beatrice
>>
>>
>> At 09.43 26/01/2011, you wrote:
>> >Dear Beatrice,
>> >
>> > are you sure that you are using the input file you attached to the
>> >previous mail?
>> >I tried to rerun it (using FLUKA2008.3d.1) but it stops at
>> >initialisation due to a lack of memory positions. Which is - I guess -
>> >due to the big number of binnings you are using.
>> >Can you please send the right file?
>> >
>> >Cheers, Florian
>> >
>> >
>> >
>> >
>> >
>> >
>> >--
>> >Dipl.-Ing. Dr. techn. Florian Sommerer
>> >Physiker
>> >Radiologische Klinik / Heidelberger Ionenstrahl-Therapiezentrum
>> >Florian.Sommerer_at_med.uni-heidelberg.de
>> >Im Neuenheimer Feld 450
>> >69120 Heidelberg
>> >Germany
>> >-----Urspr=FCngliche Nachricht-----
>> >Von: owner-fluka-discuss_at_mi.infn.it
>> >[mailto:owner-fluka-discuss_at_mi.infn.it] Im Auftrag von beatrice pomaro
>> >Gesendet: Montag, 24. Januar 2011 18:26
>> >An: fluka-discuss_at_fluka.org
>> >Betreff: Energy deposition
>> >
>> >Dear Fluka users,
>> > can you please have a look to the input file in attachment:
>> >the problem is represented by a target made of
>> >UC2 which is directly impinged by a proton beam (300microA, 70MeV),
>> >within a concrete target bunker. I used IRRPROFI to model a beam
>> >working 5000hours/year than stopping, for totally 9years.
>> >I am interested in the results in terms of energy deposition
>> >[Gev/(cm3 primary)] on the slice of shielding just in front of the
>> >target source. However in the USRBIN files I have negative values of
>> >energy deposition and 'INF' strings.
>> >Can you address me where the problem is, please?
>> >If I do not assign an IRRPROFI card for the beam irradiation profile
>> >does, in this case, the energy deposition correspond to time=3D0?
>> >
>> >Many thanks for your help,
>> >
>> >Sincerely,
>> >Beatrice Pomaro
>
> **************************************************
> Ing. Beatrice Pomaro
>
> Universita' degli Studi di Padova
> Dipartimento di Costruzioni e Trasporti
> via Marzolo, 9 - 35131 Padova (Italy)
> tel: +39 049 8275605
> e-mail: pomaro_at_dic.unipd.it
>
>
>
>
Received on Thu Jan 27 2011 - 13:38:56 CET

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