FLUKA: USRCOLL
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USRCOLL
defines a detector for a hadron fluence collision 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)
For all SDUM
's except EN-NUCL and ENERGY:
First card:
WHAT(1)
= i1 + i4 * 10000, where i1, i4, have the following meaning:
i1 = 1.0 : linear energy binning
= -1.0 : logarithmic energy binning
i4 = 0.0 : group-wise scoring for low energy neutrons
=+/-1.0 : point-wise scoring for low energy neutrons
Default
= 1.0 (linear binning, groupwise scoring)
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(3)
| < 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 (GeV)
Default
: Beam momentum value according to the BEAM option
(if no BEAM card is given, 200 GeV)
WHAT(2)
= minimum energy for scoring (GeV)
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
For SDUM
= EN-NUCL:
The energy scale for all USRCOLL estimators will be changed from energy
to energy per nucleon (for particles with baryon number = 0 or 1, i.e.
all elementary hadrons and leptons, nothing will be changed).
For SDUM
= ENERGY:
The energy scale for all USRCOLL estimators will be changed to the default,
that is total kinetic energy.
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 (or tracklength, if
the detector region volume is not specified) in energy, in units
of cm-2 GeV-1 (or cm 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 or tracklength in cm PER
ENERGY BIN per primary) one must multiply the value of each energy
bin by the width of the bin (even for logarithmic binning). This is
done automatically by the dedicated post-processing utility program
USTSUW (see Note 6).
2) If the generalised particle is 208.0 (ENERGY) or 211.0 (EM-ENRGY),
the quantity scored is differential energy fluence (or tracklength,
if the detector region volume is not specified), expressed in GeV
per cm2 (or cm GeV) 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 2500.
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 interval
overlaps with the structure of the low energy neutron groups,
one gets two separate tables. In the lower one, interval boundaries
are forced to coincide with group boundaries. For the upper one,
the program uses the input energy limits and number of intervals to
estimate the desired interval width. The number of intervals above
the upper limit of the first low-energy neutron group is recalculated
according to such width, which is readjusted to match the number of
intervals with the least greater integer.
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 Table 10.4.1.1}.
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 track-lengths
(calculated as number of collisions times the respective mean free
path!) in all regions, divided by the value set by the user for WHAT(5)
.
8) A collision estimator can only be defined for hadrons.
Example:
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. &
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