Dear Jyoti,
do not put any detector. Simply, cover your water region with URSBIN.
Maybe one for energy deposition, another for photon fluence. Choose
R-phi-z usrbin type, with Z from 0 to 500cm in 100 bins, and Radius..say
from 0 to 20 cm in
20 bins.
These you can plot as 2D plots, and already have an idea of the decrease
of dose and fluence (and see if the bin limits and size are reasonable).
Then you can plot a 1-D projection (from the USRBIn plotting page of
Flair), either averaging over all R or chossing themost central interval.
This will give you the attenuation of the dose and fluence versus z.
Weight windows will not help in your case. They are mostly helpful when
using leading particle biasing, which is not helpful here, either.
Keep in mind, again, that at 1 MeV, the mean free path for photons in
water is around 14 cm. You will never get anything after 5metres.
After 1 metre, the beam will already be attenuated by 3 orders of
magnitude (approx)
If you use importance biasing (card BIASING), the thickness of your layers
should be similar to the mean free path. You cannot do up to 5 metres,
though.
Hope this helps
Paola
> Dear Paola,
> While covering the pool with user bins, I kept the detectors at certain
> distances. Since I can't have a point detector in FLUKA, I filled the
> detectors with water.
> Still, I am getting zero energy depositions at detectors kept at 1m away
> from the source. I need a sufficient number of values to derive any curve.
> Please guide.
>
> Also, I came to know about the weight window method of biasing. How to
> define weight window for my geometry? A contsnat weight window is not
> helping.
>
> With Regards,
> Jyoti
>
> ----- Original Message -----
> From: "Paola Sala" <paola.sala_at_mi.infn.it>
> To: "Jyoti" <jyoti.grg_at_britatom.gov.in>
> Cc: "fluka-discuss" <fluka-discuss_at_fluka.org>, "owner-fluka-discuss"
> <owner-fluka-discuss_at_mi.infn.it>
> Sent: Sunday, February 9, 2020 3:12:26 PM
> Subject: Re: [fluka-discuss]: Energy Deposition is zero
>
> Dear Jyoti,
> if I understand correctly your input file, you are trying to detect
> photons after a path of 5 metres in water, and original energy of the
> photons is 1.15 MeV.
> At 1 MeV, the mean free path for photons in water is around 14 cm. It
> means that the photons have to travel 35 mean free paths before arriving
> to your detector, corresponding to an attenuation factor of about 10^-15.
> ..your bias would need to be much more aggressive than the factor 1000 in
> your input, beyond the allowed factors for the BIASING card, that can
> span up to a factor 10^10, and beyond a safe use of biasing.
> My suggestion would be to cover your pool with userbins, scoring energy
> and particle fluence, from which you can derive attenuation curves
> Hope this helps
> Paola
>
>
>>
>> Dear FLUKA Experts,
>> I have taken a point source at (0,0,0).It is shielded by a rectangular
>> pool of water around it.
>> I am calculating energy deposition at the surface of the pool, but it is
>> coming zero.
>> I tried importance sampling, yet the answer is zero.
>>
>> I have attached my input file. Kindly have a look at it.
>> Please let me know, where I am doing a mistake.
>>
>> Thank You
>>
>> With Regards,
>> Jyoti
>>
>>
>>
>>
>
>
> Paola Sala
> INFN Milano
> tel. Milano +39-0250317374
> tel. CERN +41-227679148
>
>
> __________________________________________________________________________
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>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Thu Mar 05 2020 - 17:09:43 CET