Re: AW: AW: Energy deposition

From: Alberto Fasso' <fasso_at_mail.cern.ch>
Date: Thu, 27 Jan 2011 22:25:45 +0100

Dear Beatrice,

I would like to add some clarifications to what already said by Francesco.
1) after the end of the irradiation only decay contributes to an increase
     of temperature. Obvious, since there is no prompt radiation anymore.
     The increase in a time interval <Delta t> can be assumed to be
proportional
     to the power density (GeV/(cm3 s)) integrated over that time interval
     MINUS THE TEMPERATURE LOSSES DUE TO CONDUCTION, CONVECTION OR
RADIATION.
     I stress here the last sentence, because I have the impression,
also from
     an old email by you, that you tend to neglect these effects. They
are never
     negligible except in very special cases (e.g. a well-insulated
calorimeter)
2) during irradiation, both prompt and decay radiation contribute to the
     temperature increase. Again the increase in a time interval is
proportional
     to the total power density integrated over that time interval: but
     while the contribution to GeV/(cm3 s) due to decay can be
calculated directly
     using RADDECAY/DCYTIMES/IRRPROFI, the contribution of prompt radiation
     to the increase of temperature is proportional to GeV/(cm3 primary)
multiplied
     by the integrated number of primaries in that interval.
     As explained by Francesco, you get:
     - GeV/(cm3 s) from decay: from binnings linked by DCYSCORE to a
cooling time.
       The proportionality factor to get temperature is the inverse of
the heat
       capacity: <Delta T/Delta E>
     - GeV/(cm3 primary) from prompt particles: from binnings not linked
to a
       cooling time. The proportionality factor to get temperature is
the beam
       current: primary/s

Alberto

On Thu, 27 Jan 2011, Francesco Cerutti wrote:

>
> Dear Beatrice,
>
>> Is it, then, correct if I activate the RADDECAY card, read my results as
>> GeV/(cm3 s) for the specific time instant of the scoring detector associated
>> to each USRBIN, then without rescaling them by the beam current, I have the
>> energy deposition at that specific time?
>
> yes (actually it is power density)
>
>> In this case may I use the default settings for RADDECAY?
>
> Normally lower transport thresholds (see WHAT(5)) are recommended for the
> decay radiation, tipically down to 10 KeV for photons.
>
>> My DCYTIMES are also negative, i.e. I want to score also during irradiation;
>> is in this case the energy deposition due only to radioactive decay, too?
>
> yes
>
>> I guess that for negative DCYTIMES corresponding to the beginning of
>> irradiation profile I get the results of an istantaneus analysis (that is
>> without using IRRPROFI) because energy deposition is due to prompt radiation
>> only.
>
> no (see the answer just above), in order to get the prompt contribution -
> which is the dominant one - you need a USRBIN scoring not linked to any
> cooling time, regardless of the presence of RADDECAY, DCYTIMES, IRRPROFI.
>
> 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. Cerutti,
>> thank you for solving my problem; I would like to deepen the point
>> on the use of RADDECAY, however.
>> I understand that, by not using IRRPROFI and DCYTIMES (so no RADDECAY), I
>> get GeV/(cm3 primary), while using USRBINs connected to IRRPROFI and
>> DCYTIMES (and RADDECAY) I get GeV/(cm3 s). But I think this is what I need:
>> I was interested in estimating the temperature field in concrete during and
>> after many cycles of irradiation. I can get it by energy deposition results,
>> but in this case I need not only immediate results (due only to prompt
>> radiation), but also after long periods of irradiation (due to decay
>> radiation).
>> Is it, then, correct if I activate the RADDECAY card, read my results as
>> GeV/(cm3 s) for the specific time instant of the scoring detector associated
>> to each USRBIN, then without rescaling them by the beam current, I have the
>> energy deposition at that specific time? In this case may I use the default
>> settings for RADDECAY?
>>
>> My DCYTIMES are also negative, i.e. I want to score also during irradiation;
>> is in this case the energy deposition due only to radioactive decay, too? I
>> guess that for negative DCYTIMES corresponding to the beginning of
>> irradiation profile I get the results of an istantaneus analysis (that is
>> without using IRRPROFI) because energy deposition is due to prompt radiation
>> only.
>>
>> Thank you very much
>> Sincerely,
>>
>> Beatrice
>>
>>
>>
>>
>>
>> At 12.35 27/01/2011, Francesco Cerutti wrote:
>>
>> 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
>> >
>> >
>> >
>> >
>>
>> **************************************************
>> 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
>>
>>
>>
>
>

-- 
Alberto Fass
Received on Thu Jan 27 2011 - 23:35:27 CET

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