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File Formats

This section describes the format of external datafiles used by LSP. They must be created prior to an LSP run, are specified in the input file, and must reside in the same directory as the input file.

Method 2 Scattering File

The format of the method 2 (see section method 2) scattering tables is as follows. The first line is a comment. The next line gives the dimension of the lookup table (currently this must be 2; i.e., scattered energy and scattered angle), followed on separate lines by the number of scattered energies in the table (20 in the example below), the minimum scattered energy (2041.5 eV), the maximum scattered energy (5.0e5 eV), which is equal to the incident energy, the number of scattered angles in the table (18), the minimum scattered angle (0), and the maximum scattered angle (pi).

# Scatter lookup table for Cu
         2
20
2041.5
5.0e5
18
0
3.14159

Next is a comment line followed by the lookup table itself.

# Table:
2.0415
0.0
0.173
...
...

Method 3 Backscattering File

The method 3 (see section method 3) backscattering table is a 4-dimensional lookup table. The low-energy tail of the scattered distribution is calculated using the formulation due to Vesey (Ref.[12]).

The format of the backscattering data file is as follows. The head of the file can have any number of comment lines beginning with `#'. The first line not beginning with `#' is the number of incident energies in the table:

#
# Number of incident energies
7

This is followed by one comment line and the list of incident energies in units of eV:

# Incident energies (eV)
500
1000
2000
...
...

Next is one comment line followed by the number of incident angles in the table, then one comment line, and the list of incident angles in radians:

# Number of incident angles
19
# Incident angles (rad)
0
0.087266462599716474
0.17453292519943295
0.26179938779914941
...
...

This ends the header section of the table.

# Backscattered electrons for styrene     
# Generated using invert1.pl styrene00.00.dist styrene00.00.lookup 20 20
# Total yield fraction:
0.0244459144416445
# Relative yield fraction from extrapolation:
0.00629612126033918
# Fitting parameters A, m (normalized to give relative yield):
0.00291911818959786
0.148920337349297

Next follows one comment line, the dimension of the lookup table (2, i.e., energy and angle), the number of scattered energies in the table (20 in the example below), the minimum scattered energy (2041.5 eV), the maximum scattered energy (5.0e5 eV), which is equal to the incident energy, the number of scattered angles in the table (20), the minimum scattered angle (pi/2), and the maximum scattered angle (pi).

# Table dimensions:
         2
20
2041.5
5.0e5
20
1.5708
3.14159

Next is a comment line followed by the lookup table itself.

# Table:
2041.5
1.5708
1.79096
...
...

The part of the scattered distribution below the minimum table energy (2041.5 eV in this example) is obtained from the analytic extrapolation. For energies smaller than the lowest incident energy in the table, the scattered energy distribution for the lowest incident energy is used, scaled to the actual incident particle energy.

Method 4 Cross Section File

The cross section file used by method 4 (see section method 4) is generated by the XGEN program, part of the ITS code family (Ref.[5]). A sample input file for XGEN is:

MATERIAL TA
TITLE
 20 MEV standard codes cross sections for Tantalum
ENERGY 20

This input file will generate cross section data for electron energy loss and scattering in tantalum for electron energies below 20 MeV. For ITS version 3.0, the XGEN program writes this data to a text file named `fort.11'. The name of this file (which may be changed to something more meaningful) is specified by the xgen_data_file parameter in the method 4 input.

Consult the user's manual for the ITS 3.0 codes (Ref.[6]) for more information on the XGEN program. ITS can be licensed from the Radiation Safety Information Computational Center at Oak Ridge National Laboratory (`http://epicws.epm.ornl.gov/rsic.html').

BFIELD Magnetic Field File

The datafile produced by the BFIELD code is written in the following order:

  (int) nx1 (number of grid-points in axial direction)
  (int) nx2 (number of grid-points in radial direction)
(float) dx1 (axial grid size)
(float) dx2 (radial grid size)
(float) x1s (axial starting point)
(float) x2s (radial starting point)
(float) Bz[nx2][nx1] (axial field values)
(float) Br[nx2][nx1] (radial field values)

where the field values are in normalized code units (value in gauss divided by 1704.5), and spatial dimensions are in cm. This file may be either formatted ASCII or binary type. If it is the latter, it must be indicated where the file is specified on input (see section External Fields Input).

ATHETA Magnetic Field File

The ASCII file format produced by the ATHETA code (SNL) can be generated using the following FORTRAN code:

      Open (Unit=25,File='ATHETA.DAT',Form='FORMATTED',Status='UNKNOWN')
      Write (25,5) NK+1, NL+1 
    5 Format (2I5) 
      Write (25,10) (RPOS(K),K = 1,NK)
      Write (25,10) (ZPOS(L),L = 1,NL) 
      Write (25,10) ((BRFLD(L,K),K = 1,NK),L = 1,NL) 
      Write (25,10) ((BZFLD(L,K),K = 1,NK),L = 1,NL)
   10 Format(6(1PE12.4))

where NK, NL are the number of grid-points in the radial and axial directions, RPOS, ZPOS are the radial and axial grid coordinates in meters and BRFLD, BZFLD are the radial and axial components of the magnetic field in Tesla. LSP interpolates the values onto the 2-D or 3-D simulation grid. See section External Fields Input.

MAG3D Magnetic Field File

The ASCII file produced by the MAG3D code (NRL) contains Bx, By, Bz data in cartesian coordinates as follows:

   nxmax   nymax   nzmax
      40      40      40
            x            y            z           Bx           By           Bz
     -10.0000     -10.0000     -10.0000      412.227     -412.227      1.34749
     -9.48718     -10.0000     -10.0000      426.651     -426.651      1.33026
     -8.97436     -10.0000     -10.0000      441.449     -441.449      1.28552
         .            .            .            .            .            .
         .            .            .            .            .            .
         .            .            .            .            .            .
      8.97436      10.0000      10.0000     -450.803      450.803   -0.0855465
      9.48718      10.0000      10.0000     -435.347      435.347   -0.0926784
      10.0000      10.0000      10.0000     -420.296      420.296   -0.0983440

where the field values are in units of kilogauss, and the spatial coordinates are in cm. See section External Fields Input.

MAFCO Magnetic Field File

The binary file produced by the MAFCO code contains Bx, By, Bz data in cartesian or cylindrical coordinates in a format similar to an LSP field dump, so that it may be displayed by the P4 utility. Field values are in units of gauss, and the spatial coordinates are in cm.

Fileread Particle File

The user-supplied particle data file for the fileread injection model (see section fileread) is in XDR binary format and is created by a previously run LSP simulation using an instance of particle extraction available in the [Particle Extraction] section of input. See section Particle Extraction Input. It contains the data necessary to continue a beam transport problem in a downstream region of space not contained in the first simulation.

Particle Interaction Data File

There are presently three types of data files used to characterize interactions between particle species: those for ionization events (see section ionization), those for charge-exchange events, and those for random montecarlo scattering (see section Particle Interaction Input).

For ionization, the file format is as follows:

# Table of interactions for p+ on neutral H2
# Type Num-energy / Charge Mass (twice)
1 200
1 1.836000e+03
0 3.672000e+03
#  Energy        dEdx       Sigma-ion     Nu-mom
4.690980e+02 4.004441e-14 0.000000e+00 9.094049e-20
5.045765e+02 4.575827e-14 0.000000e+00 9.962914e-20
 .
 . (for 200 energy values)
 .

Header lines beginning with # are ignored. The first integer (1) identifies this as an "ionization" table. The second integer (200) gives the number of energy values in the table. The next two lines give the charge state and mass of the interacting species (normalized to the values for a positron). These values must match exactly those specified in the [Particle Species] section (see section Particle Species Input). Following this is one or more comment lines beginning with # and finally the table of values with the following columns: energy (eV), energy loss rate (eV*cm^3/cm), ionization cross section (cm^2), momentum-transfer frequency (cm^3/cm).

For particle energies lower (higher) than the minimum (maximum) energy in the table, the values for the minimum (maximum) energy are used. If the values are independent of energy, a single entry in the table is sufficient.

For charge-exchange, the file format is:


# Table of interactions for neutral H2 on p+
# Type Num-energy / Charge Mass (twice)
2 200
0 3.672000e+03
1 1.836000e+03
#  Energy       Nu-cx        Nu-mom
4.690980e+02 8.536466e-20 5.575825e-21
5.045765e+02 9.405332e-20 5.575825e-21
 .
 . (for 200 energy values)
 .

The first integer (2) identifies this as a "charge-exchange" table. The next two lines are the same as for the ionization table above. The table of values has the following columns: energy (eV), momentum-transfer frequency due to charge-exchange (cm^3/cm), and momentum-transfer frequency due to scattering (cm^3/cm).

For montecarlo scattering, the file format is as follows:

# Table of interactions for e- on neutral He (Montecarlo type)
# Type Num-energy / Charge Mass (twice)
3 460
-1 1.000000e+00
0 7.344000e+03
# number of inelastic processes (nproc)
7
# Eaniso       Eioniz       Bparam       Delta_E_1  ... Delta_E_nproc
0.000000E+00 0.246000E+02 0.000000E+00 0.198000E+02 ... 0.240000E+02
# Energy       Sigma_el     Sigma_ioniz  Sigma_1    ... Sigma_nproc
0.000000E+00 0.495000E-15 0.000000E+00 0.000000E+00 ... 0.000000E+00
0.100000E+00 0.579524E-15 0.000000E+00 0.000000E+00 ... 0.000000E+00
 .
 . (for 460 energy values)
 .

Primary Output Data File

The primary output data files have the following format for each particle:

 WEIGHT X Y Z Vx Vy Vz

where WEIGHT is the charge weight of the macro-particle, the X/Y/Z coordinates are in cm, and the V's are the gamma-beta velocity components. The data can be spread onto discrete files, depending on the extraction_dump_interval or its related control parameters. The resulting files will have names like `primNNNN.dat', where `NNNN' is the timestep on which the data is finalized. If no dump interval or dump time is specified, all of the data will remain on a file named `primaries.dat'.

Photon Output Data File

The photon output data files have the following format for each photon:

 WEIGHT ENERGY X Y Z Vx Vy Vz

where WEIGHT is the charge weight of the originating macro-particle, ENERGY is in MeV, the X/Y/Z coordinates are in cm, and the V's are actually the unit direction vector components. The data can be spread onto discrete files, depending on the extraction_dump_interval or its related control parameters. The resulting files will have names like `photNNNN.dat', where `NNNN' is the timestep on which the data is finalized. If no dump interval or dump time is specified, all of the data will remain on a file named `photons.dat'.

Hysteresis Data File

The hysteresis data file contains a series of B-H curves used for the hysteresis volume model (see section Volume Models Input). The file format is as follows:

# B-H curves for metglas, smoothed trapezoidal functions
# number of dB/dt values
6
# number of data points
251
# alpha value
5.0
# dB/dt values in Gauss/ns
0. 8.0  18.0  27.0  45.0  62.0
# single B and multiple H values in units of Gauss and Oersted
-1.6232E+04  -2.7323E+01  . . .  -2.7323E+01
 .
 . (for 251 B-field values)
 .

Note that there are six values of H-field for each value of B-field, making six distinctive B-H curves, one for each value of dB/dt. The total collection of data should cover the complete range of possible values relevant to the desired hysteresis behavior. During the simulation, values of H-field as a function of B and dB/dt are determined by interpolation from these curves. The alpha parameter is the slope of H versus B at the origin which is needed to correctly determine the shape of "minor loop" curves, since the data are for the "major loop" only.


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