RE: Energy deposition scoring for electrons or photons

From: Georgios Tsiledakis <>
Date: Mon, 7 Mar 2011 15:19:22 +0000

Dear Paola,
I tried to follow your suggestions using the usrmed.f routine.
I have added in my input
MAT-PROP 1.0 0.0 0.0 12.0 29.0 3.
where 12.0 is the copper that surrounds the gas mixture 29.0
The region of the copper is 2.0 and of the gas 3.0
I would like to measure the energy deposited in the gas that comes only
from photons or only from electrons when the source for example is 1.3
MeV point source inside the Copper shell.
By adding in the usrmed.f the lines:
        IF ( MREG .EQ. 3 ) THEN
             IF ( IJ .EQ. 3) WEE = ZERZER
        END IF
I realise that I kill all the electrons in the region 3 (copper) that
might give photons and finally conversions into the gas. As a result, I
am getting very few which is wrong...

-If I write it as follows it is also wrong....=

        IF ( IJ .EQ. 7 ) THEN
             IF ( MREG .EQ. 3 .AND. NEWREG .EQ. 4 ) WEE = ZERZER
        END IF

Could you please let me know how to kill this particles not in the
region but in the boundary?
I had a look at the manual without success. Is it a good idea to define
a new tiny spherical shell that separates gas from copper and kill by
WEE =3D ZERZER selectively what I would like?

Thank you very much for your help
Best regards

From: [] on
behalf of paola sala []
Sent: 28 February 2011 17:35
To: Georgios Tsiledakis
Subject: Re: Energy deposition scoring for electrons or photons

Dear Georgios,
to separate electron and photon contributions yohave to set up
some user code. No automatic distinction is possible at scoring time,
since all energy deposition will be done by electrons, even when the
primary is a photon.
You can proceed in several ways. For example:
- through the usrmed.f routine, selectively kill electrons or photons at
the boundary between copper and gas
- trhough the stack user variables, set one or several flags recording
the history of the particle . This can be done with the stupre.f routine
at interactions, and/or with the bxdraw entry of mgdraw.f at boundaries.
A user-written comscw.f can then select wether to score or not

For hints on user routines, you can have a look in the manual, and also
in the lectures of the advances fluka course ( on the program page)

As for neutrons: the threshold at 20 MeV is not a a
boundary between two different transport methods. Above this, neutrons
are treated like all other hadrons. Below 20 MeV, their transport and
interactions are simulated on the basis of cross section libraries, with
the so called muti-group transport. In both cases you will get the enrgy
deposition from recoils, however below 20 MeV the recoils and reaction
products other than neutrons and photons will not be transported, their
energy will be deposited at the interaction point. ( except for
interactions on Hidrogen) Again, for a description of the low energy
nmeutron transport in fluka, please refer to the dedicated section in
the user manual

Hope this helps

On Fri, 2011-02-25 at 09:41 +0000, Georgios Tsiledakis wrote:
> Dear fluka experts,
> I had a copper sphere that surrounds a gaseous volume of Ar-CH4 at 50
> mb.
> With a modified source.f routine (thanks to your very fruitful
> explanations at the list)
> I generate photons of 1.3 MeV randomly in the copper shell and score
> at the gas using
> the EVENTBIN card and a manipulation in fortran/root.
> The energy deposition (EM) is given at the attached picture where you
> could see the Copper
> peak around 8 keV (200 entries above a background in 2 peaks)
> My questions are the following:
> 1)Is the background of around 60 counts at 8 keV purely electrons?
> 2)how I could repeat the study BUT measure the Edep only from photons
> or only from electrons?
> Since fluka gives 208 and 211 options. Is any easy way to discard
> for example conversions of Copper
> and so, all I could see at the plot to be purely electrons or the
> opposite?
> 3)There is a threshold of 20 MeV for neutrons. Can I use a neutron
> source of 2 MeV and see the recoils?
> How FLUKA treats neutron-nucleus collisions? Is it efficient for
> (C1, n) reactions? 1-2 MeV neutron
> can be used?
> Thank you very much in advance
> Best regards
> Georgios
Received on Tue Mar 08 2011 - 00:38:11 CET

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