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TRANS: Nuclear Transport Routine

Overview

The TRANS module of CREME transports the input particle fluxes (either from the FLUX or TRP modules or from a previous run of TRANS) through a thickness of shielding which you specify. This transport code takes into account both energy loss and nuclear fragmentation.

  • Unlike the old (1986) CREME program, this transport code keeps track of nuclear fragments (from the cosmic-ray projectiles). This new code should therefore be more accurate under thick shielding.
  • (However, TRANS does not track the generally low-energy and very short-range fragments produced from target nuclei in the shielding material itself.)

Inputs

At present, TRANS only offers aluminum as a shielding material.

TRANS offers two options for specifying the shielding thickness:

  • a single value, which may be given in units of mils, cm, or g/cm2 ;
  • a distribution of shielding thicknesses, from an input file.
  • In general, the input to TRANS will be a .flx file from FLUX or a trapped proton file (.tr) from TRP. (This file must be created before you run TRANS.)
  • However, it is also possible to input a .tfx file from a previous run of TRANS, in order to increment the shielding thickness.

Output

TRANS writes the transported fluxes to an output file ("something.tfx").

This file contains the differential fluxes of various species (in nuclei/m2-s-sr-MeV/nuc) vs. kinetic energy (in MeV/nuc) after transport through shielding.

TRANS output files must have a name of the form "something .tfx ". (That is, a rootname which you specify; the extension "tfx" is added automatically.) Without this extension, the file cannot be located by some of the CREME menus and on-line directory features. This extension also identifies the file as having a special format, which is required for input to the LETSPEC routine [to calculate Linear Energy Transfer (LET) spectra] and PUP routine [to calculate proton-induced SEE rates].

The .tfx file also contains header information which documents the inputs and parameters which produced it. You can examine this header information (to make sure, for example, that you've selected the .tfx file you want).

The special format of the CREME96 .tfx files suppresses the energy values. This format may be decoded into two-column tables (with energy in MeV/nuc in the first column and flux in nuclei/m2-s-sr-MeV/nuc in the second column). You can download these two-column tables to your own computer for plotting with your own software. At the top of this file will be header information (with a "%" in the second column of each header line). Note that you may have to delete some or all of these lines before passing the file to your plotting software.

.tfx files track the transported particle flux down to an energy of 0.1 MeV/nuc.

See also: Plotting CREME96 Spectra

Notes

  • 100 mils = 0.254 cm = 0.6858 g/cm2 aluminum.
  • 1000 mils = 1 inch = 2.54 cm
  • Density of aluminum = 2.702 g/cm3
  • Density of silicon = 2.330 g/cm3
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