RE: Defining a radioactive isotope as source

Hello,

Thank you Joachim, I found what I did not do and which was important
although flair gave me a hint in the dcyscore rolling menu
("semi-analogue").

It is in the manual RADDECAY section :
*********
  WHAT(1) = flag for activating radioactive decays
              = 1: radioactive decays activated for requested cooling times
> 1: radioactive decays activated in semi-analogue mode
              = 0: ignored
              < 0: reset to default
              Default = no radioactive decays
**********

I had WHAT(1)=1.0 that I usually use because I use those cooling time.
But if you don't define anyone even if radioactive decay is activated, of
course nothing will occur.
Switching to 2.0 as you did, and it goes OK.

Best regards.
Sebastien.

> Hi
>
> I do not consider myself as a FLUKA guru, but my (maybe naïve)
> understanding is the following. When you use the ISOTOPE in the beam card,
> FLUKA will sample a starting position following the spatial logic defined
> (Cartesian, cylindrical....), and consider that an unstable nuclei is at
> this position. It will then transport all decay products (depending of
> course on the transport/production threshold) using the correct energy and
> branching ratios (weight adjustment I suppose), but it does not "average"
> the secondary, the sampling is done following tabulated data....
>
> The normalization will be in that case one Bq while several "primaries"
> resulting from one decay can be transported. In my case, I see decay
> particles even though I do not have an irradiation profile and associated
> decay time (check also at the end of the output for production tables for
> different particles prompt/Radioactive decay part), which can tell you if
> the secondary are transported or not....
>
> If you use a normal BEAM card and specify the PHOTON energy for gamma
> emitters, then you can only do approximation for decay with several gammas
> and it is strictly equivalent only for sources like Cs where only 1 gamma
> is emitted.....
>
> Hope this help
> Joachim
>
>
>
> -----Original Message-----
> From: wurth_at_ipno.in2p3.fr [mailto:wurth_at_ipno.in2p3.fr]
> Sent: 27 April 2012 09:28
> To: Mina Nozar
> Cc: Joachim Vollaire; fluka-discuss_at_fluka.org
> Subject: Re: Defining a radioactive isotope as source
>
> Dear Mina,
>
> "If no radioactive isotope evolution or decay is requested [...]"
> This means that you have to activate since it is not by default the
> radioactive decay with a RADDECAY card.
>
> But after trying with Joachim's set of cards I also don't get anything
> unless I add an IRRPROFI card and at least a DCYTIMES (negative) to be
> associated with a DCYSCORE applied to a detector card (say USRBIN,
> USRTRACK). Then it goes OK, if scoring photon fluence in a proper USRTRACK
> card I get the two photon peaks.
> It challenges what I thought have been learned yesterday.
>
> Best regards.
> Sebastien.
>
>
>> Dear Sebastien,
>>
>> Thank you for your help.
>>
>> I actually do have a RADDECAY card in the input. It is the following:
>>
>> RADDECAY 1. 3. 0.0 1000010
>>
>> I also have set production and transport cuts to 20 keV for gammas,
>> e+/e-.
>> but I still don't see any interactions.
>>
>> The very fact that a RADDECAY card is necessary for a radioactive
>> source implies that the two methods are handled differently
>> (internally) by the code. So it doesn't seem like the ISOTOPE under
>> the question is looked up to see whether it is radioactive or not and
>> if so, an average for main emitted gamma energies are used to generate
>> interactions. Can one of the FLUKA gurus shed some light on this by
>> commenting on how a radioactive source is implemented and why is it
>> that I am not seeing any interactions?
>>
>> Looking in the manual Under BEAM --> SDUM, I see:
>>
>> For (radioactive) isotopes, use the name ISOTOPE and specify
>> further the isotope properties by means of option
>> HI-PROPErt.
>> In this case WHAT(1) and WHAT(2) are meaningless. If no
>> radioactive isotope evolution or decay is requested,
>> or if a
>> stable isotope is input, nothing will occur, and no
>> particle will
>> be transported.
>>
>> There is no mention of a RADDECAY card inclusion.
>> The only example on a radioactive source is for Cs-137.
>>
>> * The next BEAM card describes a 137-Cs isotropic source
>> BEAM -661.7E-6 0.0 1.E4 0.0 0.0 1.0
>> PHOTON
>>
>>
>>
>> Thank you very much and best wishes,
>> Mina
>>
>> On 12-04-26 01:02 AM, wurth_at_ipno.in2p3.fr wrote:
>>> Dear Mina,
>>>
>>> I think you gave the answer yourself.
>>> In order to activate the transport of your beampart which are the
>>> products of the Co-60 disintegration you have to put at least a
>>> raddecay card.
>>> Joachim wrote it in his "general comments" at the end of its answer.
>>>
>>> By the way I learned something as well, I thought that an IRRPROFI
>>> card was also mandatory in this case but it seems not, results will
>>> simply be normalized per unit disintegration.
>>>
>>> Best regards.
>>>
>>> Sebastien.
>>>
>>>> Dear Joachim, thank you for your response.
>>>>
>>>> I am taking baby steps in this regards...
>>>> I get results from the 2nd method (can see beampart distribution for
>>>> instance, etc).
>>>> However, I can't get any reactions using the second method. I am
>>>> using the following cards:
>>>>
>>>> BEAM 0.0 10000.0
>>>> ISOTOPE
>>>> * So an isotropic ISOTOPE beam. According to the manual, what(1)
>>>> and
>>>> what(2) are ignored.
>>>>
>>>> HI-PROPE 27.0 60.0
>>>> * Defining Co-60
>>>>
>>>> BEAMPOS 0.0 0.0 0.0
>>>> * Starting position of the beam (x,y,z : 0,0,0)
>>>>
>>>> BEAMPOS 0.0 1. 0.0
>>>> SPHE-VOL
>>>> * The source is uniformly distributed in a sphere of radius 1
>>>>
>>>>
>>>>
>>>> Why do I need to use a RADDECAY, DCYTIMES, DCYSCORE, if all I am
>>>> interested (in the beginning) is to look at the beampart
>>>> distribution?
>>>>
>>>> Are these necessary for production of the gammas from the decay of
>>>> Co-60?
>>>>
>>>> Thank you and best wishes,
>>>> Mina
>>>>
>>>>
>>>> On 12-04-24 01:23 PM, Joachim Vollaire wrote:
>>>>> Dear Mina,
>>>>>
>>>>> Here are some answers to your questions :
>>>>>
>>>>> 1) Does the first method, i.e. using the HI-PROPE option, do the
>>>>> same, i.e. use isotropic and mono-energetic gammas with energy as
>>>>> the average energy of (1332.5 keV and 1173.2 keV)?
>>>>>
>>>>> Yes in theory both approach should be the same if you are careful
>>>>> with the normalization. Using the built-in source is however more
>>>>> straightforward, especially for isotopes with many gamma lines...
>>>>> In the case of Co you could do one photon run with one energy and
>>>>> another one with the other line. As the results are normalized per
>>>>> primary, you would need to add the scored quantity of the two runs
>>>>> and then multiply per the Co60 activity as one disintegration leads
>>>>> to the production of two photons....
>>>>>
>>>>> 2) Can the activity of the radioisotope be incorporated in the
>>>>> source definition?
>>>>> If you use the built-in source, the results are normalized to one
>>>>> disintegration. This mean than when you post process the results
>>>>> you have to normalize to the activity, as for a "prompt"
>>>>> calculation where results are normalized to one primary particle....
>>>>>
>>>>> 3) Is it possible to define multiple radioisotopes as sources,
>>>>> taking into account activities of each?
>>>>>
>>>>> The best is to run independent calculations for each isotopes, then
>>>>> normalize to the corresponding activity (see 2) above) and add the
>>>>> results....
>>>>>
>>>>> More general comment, you must not forget to call the particle
>>>>> decay with RADDECAy for ISOTOPE used with the BEAM card. I have
>>>>> attached below some cards taken from a calculations where I was
>>>>> looking at the dose rate from Ar41 decay in air in a 300 X 300 X
>>>>> 300 cm3 room. The specific activity in the air was equal to 70
>>>>> kBq/m3, thus to get the results in microSv/h the normalization
>>>>> factor I was using is the following :
>>>>>
>>>>> (3600/1.0e06)*3*3*3*70e3
>>>>>
>>>>> *
>>>>> BEAM
>>>>> 1.0ISOTOPE
>>>>> BEAMPOS 0.0 300.0 0.0 300.0 0.0
>>>>> 300.0CART-VOL
>>>>> BEAMPOS 0.0 0.0 0.0
>>>>> *
>>>>> HI-PROPE 18. 41.
>>>>>
>>>>> RADDECAY 2.0
>>>>> DCYSCORE -1.0 0. 0. DR-001 DR-001
>>>>> USRBIN
>>>>> *
>>>>> *
>>>>> USRBIN 10.0 DOSE-EQ -45.0 200.0 20.0
>>>>> 200.0DR-001
>>>>> USRBIN -200.0 -20.0 -200.0 100.0 1.0
>>>>> 100.0&
>>>>>
>>>>>
>>>>> Hoping this help
>>>>>
>>>>> Joachim
>>>>>
>>>>> -----Original Message-----
>>>>> From: owner-fluka-discuss_at_mi.infn.it
>>>>> [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of Mina Nozar
>>>>> Sent: 24 April 2012 03:12
>>>>> To: fluka-discuss_at_fluka.org
>>>>> Subject: Defining a radioactive isotope as source
>>>>>
>>>>> Hello everyone.
>>>>>
>>>>> I have a couple of questions in regard to how radioactive isotopes
>>>>> (as
>>>>> sources) are handled in FLUKA.
>>>>>
>>>>> Looking through the "Sources" slides under
>>>>> http://www.fluka.org/fluka.php?id=course&sub=program&navig=2&which=
>>>>> portugal2010
>>>>>
>>>>> To set up Co-60 as the radioactive source, it seems there are two
>>>>> options.
>>>>> One through the use of the "BEAM -> ISOTOPE" and "HI-PROPE ->
>>>>> Co-60
>>>>> A,Z settings" and
>>>>> another through the use of the "BEAM -> average energy for the two
>>>>> main gamma energies emitted by Co-60".
>>>>>
>>>>> 1) Does the first method, i.e. using the HI-PROPE option, do the
>>>>> same, i.e. use isotropic and mono-energetic gammas with energy as
>>>>> the average energy of (1332.5 keV and 1173.2 keV)?
>>>>>
>>>>> 2) Can the activity of the radioisotope be incorporated in the
>>>>> source definition?
>>>>>
>>>>> 3) Is it possible to define multiple radioisotopes as sources,
>>>>> taking into account activities of each?
>>>>>
>>>>>
>>>>> Thank you,
>>>>> Mina
>>
>>
>
>
>
Received on Sat Apr 28 2012 - 12:40:30 CEST