Re: Can FLUKA (or flair ) be used to caculate region volumes?

From: Vittorio Boccone <boccone_at_cern.ch>
Date: Fri, 13 Apr 2012 17:44:49 +0200

Hi Walker,
    calculating volumes of complex regions containing qua etc.. can be
pretty complicate. As Anna suggested there are some trick.
To get an estimation of the volumes from FLUKA you must in any case run
a preliminary simulation.

The one I like the most is a variation of Anna's suggestion.

The trick I use is:
- Set a BEAM particle with fixed energy (for example E=1GeV PHOTONS)
- Use an additional beampos card to flood a parallelepiped (or cyl or
sphere) containing your region. Calculate the volume "Vf" of the flooded
area.
- Disable the beam particle transport for the BEAM particle type so the
energy will be released "in loco" w/o transport (i.e. for photon -> EMF
OFF).
- Score the energy released by the particle "per region" in an ASCII file.

The energy density (per primary) in the area flooded with particles.

Now the scored value will contain the total energy released in each
region which is proportional the Volume of the region you want to
calculate and tho the energy density in the flooded space.

Using 1GeV particle make the calculation simple as the unknown volume be
just the Volume of the flooded space times the energy deposited in the
unknown volume region and then divided by 1GeV.

This way you don't have to change the definition of your material and
you need in principle very few cards and an easy calculation.

For example TARGET here is the region with unkown volume which must be
completely contained in the CART-VOL flood area:

(Please look at this lines with a fixed width font....)
* Define the beam position
BEAMPOS 0.0 0.0 5.0 NEGATIVE
* Flood a 10x10x10 box centered at x,y,z=0,0,+5
BEAMPOS 0.0 10. 0.0 10. 0.0 10.CART-VOL
EMF EMF-OFF
* Score per regions
USRBIN 12. ENERGY 21. TARGET GammaEn
USRBIN BLKBODY 1. &

This way you can also get multiple volumes at the same time (all must be
inside the flooded area!)
>10M of primaries are simulated quickly with this parameters.

cheers

Vittorio

On 12/04/2012 22:16, Anna Ferrari wrote:
> Hallo Walker,
>
> in FLUKA you don't have at the moment the analytical calculation of the region
> volumes (you can see that at the contrary for some special scoring purpose you
> have to provide in input the region volumes, for a correct normalization).
>
> You can, however, calculate your volumes in an indirect, pure Monte Carlo way,
> using the tracklength estimator in the volume you want to calculate and the
> fact that the total tracklength is proportional to the volume itself.
>
> The steps are the following (thanks to Alberto Fasso'!):
> - Assign vacuum to all regions.
> - Define a source of any stable particle, uniformly distributed over a sphere
> that contains the whole geometry and randomly directed inwards with a cosine
> distribution. You can define a such source using BEAMPOS with SDUM=FLOOD.
> - Define a tracklength detector USRTRACK for each region, putting in input the
> volume = 1.
> - Run. The total tracklength, s, scored in each region is proportional to the
> volume v of the region. The volume can be carried out considering that the
> average chord length, L, of the source sphere is known and is L [= 4/3 R ] = 4V/A,
> where R is the radius of the sphere, V is the volume and A the surface.
> We have the proportion: v/V = s/L -> v = s (V/L) = s A/4 = s pi R**2
>
> Obviously your result is approximate and depends on your statistics...
>
> I guess that the option in Simple Geo, when you can use it and with the limit
> you wrote, remains the best solution.
>
> Hope it helps,
> regards,
> Anna
>
>
>
> Am Thu, 12 Apr 2012 16:39:34 +0800 schrieb wdx456<wdx456_at_mail.ustc.edu.cn>:
>> Thank you, Sion£¡
>>
>> Such function in simplegeo is really good. However,Since sometimes the FLUKA
>> model I have can't be displayed in simplegeo normally, but quite good in
>> flair .
>> Besides, it seems that simplegeo can't deal with the QUA body.
>>
>> So,I'm wondering if the region volume caculation work could be finished
>> within the FLUKA software itself.
>>
>>
>> Sincerely
>>
>> Walker
>>
>>
>>
>>
>>
>> From: Sion Koren
>> Date: 2012-04-11 18:29
>> To: wdx456
>> Subject: Re: Can FLUKA (or flair ) be used to caculate region volumes?
>> Greetings,
>> You can use Dr. Theis software SimpleGeo for that purpose.
>>
>>
>> Good luck,
>> Sion
>>
>> Sent from my iPhone
>>
>> On Apr 11, 2012, at 2:44 AM, wdx456<wdx456_at_mail.ustc.edu.cn> wrote:
>>
>>
>>
>> Dear FLUKA experts and users,
>>
>> I come across a situation that FLUKA region volumes need to be caculated
>> for further purposes. Can this be realized in FLUKA? If so, how?
>>
>>
>> Thanks!
>>
>> Walker

-- 
Dr. Vittorio Boccone - University of Geneva
o Address:
    UniGe: Département de physique nucléaire et corpusculaire
           24 Quai Ernest-Ansermet, CH-1211 Geneve 4, Switzerland
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o E-mail:
    vittorio.boccone_at_unige.ch
    vittorio.boccone_at_cern.ch
o Phone:
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Received on Sun Apr 15 2012 - 12:41:30 CEST

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