--- Scoring
Q:
I would like to calculate energy depositions in a calorimeter;
something like the summary table that FLUKA prints out at the end.
How can I do it?
A:Energy deposition scoring can be done in FLUKA in several ways:
- Option SCORE: gives you energy deposited (total or electromagnetic
only) in each region. However, it does not provide a distribution
as that of the summary table.
- Option USRBIN: does the same in a detailed spatial mesh independent
of geometry. The variant EVENTBIN gives the results separately
for each primary event.
- Option EVENTDAT: gives a detailed energy balance per region, similar
to that of the summary table at the end of the standard output but more
extended, at the end of each primary event.
EVENTDAT produce binary output files: EVENTBIN can produce text or binary
output files, depending on the user choice. The instructions for
reading them are listed in the manual.
The energy deposited in scintillators can be weighted by a quenching factor
(option TCQUENCH).
The user routine comscw.f can be called at every energy deposition
event (see option USERWEIG) and can be used to multiply the amount
deposited by a weighting factor or to perform any other manipulation.
Be aware also that the distribution of deposited energy as
electromagnetic, heavy recoil, ionisation etc. is in part arbitrary:
for instance changing the threshold for delta-ray production can
affect the ratio between ionisation and electromagnetic; similarly,
if recoils are transported, their energy is deposited as ionisation,
otherwise it is deposited as recoil energy, etc.
Q:
The output corresponding to the SCORE command announces in the title of
each column:
"GeV/cm**3/one beam particle" or "Stars/cm**3/one beam particle"
However, the units actually used seem to be respectively GeV/beam particle
and Stars/beam particle. Why does it say "per cm**3"?
A:The volume used to calculate the energy density and the star density is the
one reported in the second column ("volume in cubic cm"), which is equal to
1.0 by default. The actual region volumes can be optionally input by the user
at the end of the geometry section of the input (just before the GEOEND card),
provided the IVOPT variable in the Geometry Title card has been set equal to 3.
As many volume definition cards must be given as is needed to input a volume
for every region. The input variable is an array VNOR(I) = volume of the
Ith region. The format is (7E10.5). Volume data are used by FLUKA only to
normalise energy or star densities in regions requested by the SCORE command.
Q:
How can I use FLUKA to score n-tuples with HBOOK?
A:A detailed example is available from the FLUKA web page. See:
"Demonstration of simple muon transport. In addition, one can learn how to
link FLUKA with the CERN library in order to utilize HBOOK functionality"
in http://www.fluka.org/Examples.shtml
Q:
I would like to calculate the dose generated by gamma and neutron. How
can I do this?
A:You can calculate dose with a special fluscw routine named deq99c.f,
which can be found in the subdirectory flutil, and using the estimators
USRBIN, USRBDX, USRTRACK. Attention, the routine converts fluence into
dose equivalent, not absorbed dose. For the latter, there is an example
comscw in the FLUKA manual, which is converting GeV/cm3 into J/kg = Gy .
Q:
How can I score a histogram of LET?
A:LET can be scored with the USRYIELD card. The bins will be in units
of keV/(micron g/cm^3 ). Note that when scoring with USRYIELD differential
yields are scored over any desired number of intervals for what concerns
the first quantity, but over only one interval for the second quantity.
However, the results are always expressed as second derivatives and not
as interval-integrated yields. If LET is your first quantity the content
of your bins will be normalized to unit interval of your second
variable. Furthermore, WHAT(6) of the continuation card of USRYIELD
must contain the code of the material in which the LET has
to be calculated: it is not taken to be equal to the one of the ingoing
region, and if absent will be put equal to Hydrogen (material number 3,
the first non-vacuum in fluka)
Q:
How can I calculate a spectrum in energy per nucleon independent of
the ion?
A:This can be achieved by using the user routine fluscw.f, however in
a non-standard way: That means that you don't assign any value to FLUSCW
(leave it at the default value = ONEONE), but exploit the fact that
fluscw.f is called at tracklength scoring to manipulate the energy of
the ion. Put the following lines in fluscw.f:
...................................
INCLUDE '(FHEAVY)'
INCLUDE '(PAPROP)'
...................................
FLUSCW = ONEONE
IF (-6 .LE. IJ ) THEN
IA = IBARCH(IJ)
ELSE IF (IJ .LT. -6) THEN
IA = IBHEAV(-IJ)
END IF
PLA = -PLA/DBLE(IA)
Of course, in your USRTRACK commands must set the maximum and minimum
energy of the spectrum in a way consistent with the fact that it will
be a spectrum of E/n and not of E.
Q:
When scoring activity at a certain cooling time by associating a
RESNUCLE card with the DCYSCORE card to that cooling time I obtain results,
e.g., for 24Na, which are not identical to the activity which I calculate
offline based on a residual nuclide scoring (RESNUCLE without associating
it to a certain cooling time) and exponential built-up and decay.
How can this be explained?
A:This happens when the residual nucleus (obtained by RESNUCLE) decays to
another radioactive nucleus. RESNUCLE gives you the parent nucleus, but
not the daughter. On the other hand, when you use DCYTIMES, FLUKA follows
the decay of the parent and gives you the daughter (and sometimes even
the daughter of the daughter). This is obtained using the full Bateman
equations which govern the chain of nuclear transformations, see for
instance
http://www.neutron.kth.se/courses/transmutation/Bateman/Bateman.html
In case of 24Na the nuclide is produced in at least two different ways:
1) directly, and 2) indirectly by the decay of another nucleus.
Probably it is 24Ne, which decays into 24Na with a half-life of about
3 min: check your RESNUCLE results if you get any 24Ne nucleus.