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USRTRACK


    defines a detector for a track-length fluence estimator

    See also USRBDX, USRBIN, USRCOLL

    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)
= 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(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 8)
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 track-length detector. Max. 10 characters. Continuation card:
WHAT(1)
= maximum kinetic 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 kinetic energy for scoring (default: 0 if linear binning, 0.001 GeV otherwise) 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.
WHAT(3)
..
WHAT(6)
: not used
SDUM
= & in any position in column 71 to 78 For
SDUM
= EN-NUCL: The energy scale for all USRTRACK and 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 USRTRACK and USRCOLL estimators will be changed to the default, that is total kinetic energy.
Default
(option not given): no tracklength estimator detector IMPORTANT! ----------
Notes:
1) IMPORTANT! The results of USRTRACK 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 (ENERGY) or 211 (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 tracklength + collision detectors (see option USRCOLL) that the user can define is 2500. 4) The logical output unit for the estimator results (
WHAT(3)
of the first USRTRACK 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 USRTRACK and USRCOLL 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 structure overlaps with that of the low energy neutron groups, interval boundaries are forced to coincide with group boundaries and no interval can be smaller than the corresponding group. Actually, the program uses the requested 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. To preserve the requested upper energy limit, the width of the first interval above the low energy group may be smaller than that of the others. 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) If the scored fluence is that of a generalised particle which includes neutrons (e.g. ALL-PART, ALL-NEUT, NUCLEONS, NUC&PI+-, HAD-NEUT, and even ENERGY), the spectrum is presented in two separate tables. One table refers to all non-neutron particles and to neutrons with energies > 20 MeV. The second table refers only to neutrons with energy < 20 MeV, and its interval structure is that of the neutron energy groups. In case an interval crosses 20 MeV, it will include the contribution of neutrons with energy > 20 MeV and not that of neutrons with energy < 20 MeV. 7) A program USTSUW is available with the normal FLUKA code distribution in directory $FLUPRO/flutil. USTSUW reads USRTRACK 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). 8) Setting
WHAT(4)
= -1 will provide the sum of the track-lengths in all regions, divided by the value set by the user for
WHAT(5)
.
Example:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
USRTRACK 1.0 PHOTON -24.0 16.0 4500.0 150.PhotFlu USRTRACK 1.5 0.0 0.0 0.0 0.0 0. &
* Calculate photon fluence spectrum in region 16 from 0 to 1.5 GeV, in
* 150 linear energy intervals. Write unformatted results on
* unit 24. The volume of region 16 is 4500 cm3.

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