Re: Question from Irina Semenova: Energy deposition in FLUKA (fwd)

From: Alberto Fasso' (
Date: Tue Jan 07 2003 - 17:15:54 CET

Several people have pointed out to me that my answer to a question by Irina
Semenova, nearly a month ago, could be somewhat misleading. Therefore, I will
try to be more precise.
The question, which had been forwarded to this list by Giuseppe Battistoni,

> > My question is:
> > What does the energy deposition from "generalized
> > particle 208(ENERGY)" mean in this context? Is it some physical
> > energy deposition or I have to subtract this value from the total
> > energy deposition?
The context mentioned above was the GEODEN routine (under ENTRY GEODEN),
In order to find out which particle was depositing energy, Irina was looking at
the value of JTRACK, which in most cases would give the code of the "current
particle". In some cases, however, she found that JTRACK = 208.

In my answer, I said that
> particle code 208 means kerma energy, i.e. energy
> transferred to particles which are not better identified and are assumed to
> deposit all their energy at the point of production.
> This happens mainly in low-energy neutron reactions where the recoils or
> heavy fragments are not explicitely produced and transported.

Now, some colleagues have objected that when writing input for SCORE or USRBIN,
208 means "all energy deposited", not only kerma which could not be assigned to
a specific particle.

This is correct, but my answer was limited to the context mentioned by Irina. I
did not say that 208 _always_ means low-energy neutron kerma, but only as a
value of JTRACK at the time of energy deposition.

I hope that this removes all ambiguities.


Alberto FassÚ
CERN-EP/AIP, CH-1211 Geneve 23 (Switzerland)
Phone: (41 22) 767 2398    Fax: (41 22) 767 9480

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