From: "paola sala" <paola.sala_at_mi.infn.it>
To: "Raksha Rajput" <rakshak_at_britatom.gov.in>
Cc: fluka-discuss_at_fluka.org
Sent: Friday, August 7, 2020 8:04:59 PM
Subject: Re: [fluka-discuss]: Surface dose rate calculations
Hello
given that your geometry is cylindrically symmetric, I would suggest a
cylindrical binning.
Okay, noted.
And, I do not see the need to have more than one bin in phi. Again, the
geometry is phi-symmetric and the source is on the axis of the cylinder,
there cannot be any phi-dependence in the results except for statistical
fluctuations, and you'll gain a lot of statistics integrating over 2pi in
phi.
But if the source is placed at (4.6,0,0), the dose-Eq at x= -5.0445,y=0,z=0 will be different from that at x= +5.0445,y=0,z=0. Does this not imply the dependence of dose -eq on phi ? As I understand, phi varies from 0 to pi, from +X to-X via +Y and phi varies from 0 to -pi, from +X to -X via -Y. Hence the values are listed from -pi to +pi and I pick the bin value numbered 180th and 181st (from 360 bin values) to get the dose-Eq at x=+5.0445,y=0,z=0 (that is phi = 0.01744 rad and phi = - 0.01744 rad). Am I missing some point ?
Then: do you want to score dose or dose-eq? I see two different quantities
in the output files.
Scored Dose-Eq. ('Dose' was written by mistake in SDUM, in one of the files).
About the difference in statistics: if you score at z=0 in both cases,
the solid angle will be different for the two cases, thus the statistics
will be different.
Thank you .
Regards
Paola
Kindly clarify a little more. Thanks and regards,
Raksha.
Dear Experts,
We have tried to calculate maximum surface dose rate on the surface of a
SS cup (with center at (0,0,0) and outer radius 5.0445 cm) when the source
is at (4.6,0,0).
We tried this with Cartesian binning and R-phi-Z binning and scored
DOSE-EQ.
Please find attached the input files for 765.8 keV photon for both type of
binnings and the results obtained (.lis fles).
We would request you to comment on the correctness of the input and the
results obtained.
Can you please suggest which of the two binnings is advisable in our case
? Or, both can be used ?
As we needed the dose rate at a point, we have reduced the volume of the
bin to 1 mm^3 approx. - is this okay as the statistical errors seem less ?
(We also found that when the source is at (0,0,0), the statistical errors
seem to increase for 1 mm^3 binning detector, when compared to source at
(4.6,0,0). We couldn't understand why. Please throw some light on this. )
Kindly suggest any improvement to evaluate the dose rate at a point using
FLUKA.
Can you provide some example of using "special user defined 3D binning" in
USRBIN ?
Thanks and regards,
Raksha Rajput.
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Sat Aug 08 2020 - 09:42:49 CEST