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, October 16th 2024 (last respin 2024.1.2) 06-May-2024
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USRCOLL
defines a detector for a collision fluence estimator
See also USRBDX, USRBIN, USRTRACK
The full definition of the detector may require two successive cards
(the second card, identified by the character '&' in any column > 70,
must be given unless the corresponding defaults are accepted)
First card:
WHAT(1) = 1.0 : linear binning in energy
= -1.0 : logarithmic binning in energy
Default = 1.0 (linear binning)
WHAT(2) = (generalised) particle type to be scored
Default = 201.0 (all particles)
WHAT(3) = logical output unit:
> 0.0 : formatted data are written on WHAT(3) unit
< 0.0 : unformatted data are written on |WHAT(3)| unit
Values of |WHAT(1)| < 21 should be avoided (with the
exception of +11).
Default = standard output unit
WHAT(4) > 0: region defining the detector
= -1: all regions (see Note 7)
Default = 1.0
WHAT(5) = volume of the detector in cm**3
Default = 1.0
WHAT(6) = number of energy bins
Default = 10.0
SDUM = any character string (not containing '&') identifying the
collision detector (max. 10 characters)
Continuation card:
WHAT(1) = maximum energy for scoring
Default: Beam particle total energy as set by the BEAM
option (if no BEAM card is given, the energy corresponding
to 200 GeV/c momentum will be used)
WHAT(2) = minimum energy for scoring
Note that the lowest energy limit of the last neutron group
is 1.E-14 GeV (1.E-5 eV) for the 260 data set.
Default = 0.0 if linear binning, 0.001 GeV otherwise
WHAT(3)..WHAT(6) : not used
SDUM = & in any position in column 71 to 78
Default (option not given): no collision estimator detector
IMPORTANT!
Notes:
- 1) IMPORTANT! The results of a USRCOLL collision estimator are always
given as DIFFERENTIAL distributions of fluence in energy, in units
of cm-2 GeV-1 per incident primary unit weight). Thus, for example,
when requesting a fluence energy spectrum, to obtain INTEGRAL BINNED
results (fluence in cm-2 PER ENERGY BIN per primary) one must
multiply the value of each energy bin by the width of the bin (even
for logarithmic binning).
- 2) If the generalised particle is 208.0 (ENERGY) or 211.0 (EM-ENRGY),
the quantity scored is differential energy fluence, expressed in GeV
per cm2 per energy unit per primary. That can sometimes lead to
confusion since GeV cm-2 GeV-1 = cm-2, where energy does not appear.
Note that integrating over energy one gets GeV/cm2.
- 3) The maximum number of collision + tracklength detectors (see
option USRTRACK) that the user can define is 400. This value
can be changed by modifying the parameter MXUSTC in member
USRTRC of the flukaadd library or directory and then
re-compiling and linking FLUKA.
- 4) The logical output unit for the estimator results (WHAT(3) of
the first USRCOLL card) can be any one of the following:
-
the standard output unit 11: estimator results will be
written on the same file as the standard FLUKA output
-
a pre-connected unit (via a symbolic link on most UNIX systems,
ASSIGN under VMS, or equivalent commands on other systems)
-
a file opened with the FLUKA command OPEN
-
a file opened with a Fortran OPEN statement in a user-written
initialisation routine such as USRINI, USRGLO or SOURCE (see (13))
-
a dynamically opened file, with a default name assigned by the
Fortran compiler (typically fort.xx or ftn.xx, with xx equal
to the chosen logical output unit number).
The results of several USRCOLL and USRTRACK detectors in a same FLUKA
run can be written on the same file, but of course only if they are
all in the same mode (all formatted, or all unformatted).
It is also possible in principle to write on the same file the
results of different kinds of estimators (USRBDX, USRBIN, etc.) but
this is not recommended, especially in the case of an unformatted
file, because it would make very difficult any reading and analysis.
- 5) When scoring neutron fluence, and the requested energy bin structure
overlaps with that of the low energy neutron groups, bin boundaries
are forced to coincide with group boundaries and no bin can be
smaller than the corresponding group.
Actually, the program uses the requested energy limits and
number of bins to estimate the desired bin width. The number
of bins above the upper limit of the first low-energy neutron
group is recalculated according to such width.
Note that the lowest energy limit of the last neutron group
is 1.E-14 GeV (1.E-5 eV) for the 260 data set.
All group energy boundaries are listed in two Tables in (10).
- 6) A program USTSUW is available with the normal FLUKA code distribution
in directory $FLUPRO/flutil. USTSUW reads USRCOLL results in binary
form from several runs and allows to compute standard deviations. It
returns differential and cumulative fluence, with the corresponding
percent errors, in a file, and differential fluence in another file
formatted for easy plotting. It also returns a binary file that can
be read out in turn by USTSUW. The content of this file is
statistically equivalent to that of the sum of the files used to
obtain it, and it can replace them to be combined with further
output files if desired (the USTSUW program takes care of giving it
the appropriate weight).
- 7) Setting WHAT(4) = -1 will provide the sum of the collisions in
all regions, divided by the value set by the user for WHAT(5).
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
USRCOLL -1.0 NEUTRON 23.0 15.0 540.0 350. NeutFlu
USRCOLL 250.0 1.E-14 0.0 0.0 0.0 0. &
* Calculate neutron fluence spectrum in region 15 from thermal energies to
* 250 GeV, in 350 logarithmic energy intervals. Write formatted results on
* unit 23. The volume of region 15 is 540 cm3.
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