Re: 131-Iodine

From: Francesco Cerutti <>
Date: Fri, 25 Sep 2009 01:49:39 +0200

Dear Ernesto,

in fact the suspicion of Alfredo turned out to spot the reason for the
wrong result you reported.
When activating the decay radiation production and transport by RADDECAY
in the non-analogue mode (WHAT(1)=1.0), intended to score quantities of
interest at the requested cooling times via DCYSCORE association of the
respective estimators, the scoring by regions in the output file - which
does not refer to any cooling time - makes no sense in case of branching
along the decay path. That is because, in the mentioned mode, FLUKA
follows all branches without weighing them, and assigns then the proper
weight to the resulting particles only when scoring for a given cooling
time (on which the weight depends as well).
So you can get the correct value of deposited energy either by integrating
over a USRBIN mesh - giving always energy DENSITY - like the one you
implemented for an equilibrium time (of course limiting the integration to
your target volume), or still looking at the scoring by regions in the
.out file but with WHAT(1)>1.0 in RADDECAY, i.e. asking for semi-analogue
decay (have a look at the card documentation in the manual; there no
cooling times are relevant).

I take this opportunity to mention that in the semi-analogue mode
estimators can include the decay contribution (on top of the prompt one,
which in your case does not exist since your beam particle is an ISOTOPE)
through association by DCYSCORE with a cooling time index <= -1.0.

Finally, your interpretation of the values in the standard output table as
totals over the region is definitely correct, but the head labels are
fully correct too, since they clearly refer to a normalization volume of
1cm3 as indicated in the third column. The user, if he wishes, can input
the actual region volume list before the GEOEND card, provided that this
is declared in the geometry title card, and will then get in the table
actual density values.



Francesco Cerutti
CH-1211 Geneva 23
tel. ++41 22 7678962
fax ++41 22 7668854
Received on Fri Sep 25 2009 - 08:45:14 CEST

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